Misplaced Pages

#465534

121-449: A video floppy could store up to 25 frames either in the NTSC or PAL video standards, with each frame containing 2 fields of interlaced video . The video floppy also could store 50 frames of video, with each frame of video only containing one field of video information, recorded or played back in a " skip-field " fashion. Video floppies were first demonstrated by Sony and introduced under

242-642: A Tang dynasty medical text written by the Chinese physician Su Kung in 659, and appeared in Germany in 1528. During the Islamic Golden Age Dentistry was discussed in several famous books of medicine such as The Canon in medicine written by Avicenna and Al-Tasreef by Al-Zahrawi who is considered the greatest surgeon of the Middle Ages , Avicenna said that jaw fracture should be reduced according to

363-496: A still-store system for stills & graphics for use in a television production, or for on-air slides used for station identification or during technical difficulties (such as a "Please Stand By" still). The video floppy was available as a data variant, which was sold as the Sony 2inch Data Disk PD-1 for use in its own PJ-100 "PRODUCE 100" word processor.The PRODUCE series began with the 100 and later included several other models, such as

484-540: A video camera , VCR , video capture card , or computer graphics output). Some VF recorders also had the feature of recording a couple of seconds of audio that accompanied each video frame. The recording media in a video floppy is a flexible magnetic disk 47 mm (1.9 in) in diameter and 40 μm (0.0016 in) thick. The disk is housed in a rectangular cartridge with one chamfered corner for orientation, measuring 60 mm × 54 mm × 3.6 mm (2.36 in × 2.13 in × 0.14 in);

605-531: A bid to incorporate the school. Studies show that dentists that graduated from different countries, or even from different dental schools in one country, may make different clinical decisions for the same clinical condition. For example, dentists that graduated from Israeli dental schools may recommend the removal of asymptomatic impacted third molar (wisdom teeth) more often than dentists that graduated from Latin American or Eastern European dental schools. In

726-537: A color subcarrier of precisely 315/88 MHz (usually described as 3.579545 MHz±10 Hz). The precise frequency was chosen so that horizontal line-rate modulation components of the chrominance signal fall exactly in between the horizontal line-rate modulation components of the luminance signal, such that the chrominance signal could easily be filtered out of the luminance signal on new television sets, and that it would be minimally visible in existing televisions. Due to limitations of frequency divider circuits at

847-453: A color image. When a transmitter broadcasts an NTSC signal, it amplitude-modulates a radio-frequency carrier with the NTSC signal just described, while it frequency-modulates a carrier 4.5 MHz higher with the audio signal. If non-linear distortion happens to the broadcast signal, the 3.579545 MHz color carrier may beat with the sound carrier to produce a dot pattern on the screen. To make

968-521: A consequence, the ATSC digital television standard states that for 480i signals, SMPTE C colorimetry should be assumed unless colorimetric data is included in the transport stream. Japanese NTSC never changed primaries and whitepoint to SMPTE C, continuing to use the 1953 NTSC primaries and whitepoint. Both the PAL and SECAM systems used the original 1953 NTSC colorimetry as well until 1970; unlike NTSC, however,

1089-772: A dental team, which often consists of a dentist and dental auxiliaries (such as dental assistants , dental hygienists , dental technicians , and dental therapists ). Most dentists either work in private practices ( primary care ), dental hospitals, or ( secondary care ) institutions (prisons, armed forces bases, etc.). The modern movement of evidence-based dentistry calls for the use of high-quality scientific research and evidence to guide decision-making such as in manual tooth conservation, use of fluoride water treatment and fluoride toothpaste, dealing with oral diseases such as tooth decay and periodontitis , as well as systematic diseases such as osteoporosis , diabetes , celiac disease , cancer , and HIV/AIDS which could also affect

1210-648: A few countries, to become a qualified dentist one must usually complete at least four years of postgraduate study; Dental degrees awarded around the world include the Doctor of Dental Surgery (DDS) and Doctor of Dental Medicine (DMD) in North America (US and Canada), and the Bachelor of Dental Surgery/Baccalaureus Dentalis Chirurgiae (BDS, BDent, BChD, BDSc) in the UK and current and former British Commonwealth countries. All dentists in

1331-486: A higher vertical resolution, but a lower temporal resolution of 25 frames or 50 fields per second. The NTSC field refresh frequency in the black-and-white system originally exactly matched the nominal 60 Hz frequency of alternating current power used in the United States. Matching the field refresh rate to the power source avoided intermodulation (also called beating ), which produces rolling bars on

SECTION 10

#1733085254466

1452-480: A minimum of eight cycles of the unmodulated (pure original) color subcarrier. The TV receiver has a local oscillator, which is synchronized with these color bursts to create a reference signal. Combining this reference phase signal with the chrominance signal allows the recovery of the I ′ {\displaystyle I^{\prime }} and Q ′ {\displaystyle Q^{\prime }} signals, which in conjunction with

1573-428: A process called QAM . The I ′ Q ′ {\displaystyle I^{\prime }Q^{\prime }} color space is rotated relative to the difference signal color space, such that orange-blue color information (which the human eye is most sensitive to) is transmitted on the I ′ {\displaystyle I^{\prime }} signal at 1.3 MHz bandwidth, while

1694-459: A program using the NTSC "compatible color" system was an episode of NBC's Kukla, Fran and Ollie on August 30, 1953, although it was viewable in color only at the network's headquarters. The first nationwide viewing of NTSC color came on the following January 1 with the coast-to-coast broadcast of the Tournament of Roses Parade , viewable on prototype color receivers at special presentations across

1815-548: A remarkable achievement for the period. Major advances in science were made in the 19th century, and dentistry evolved from a trade to a profession. The profession came under government regulation by the end of the 19th century. In the UK, the Dentist Act was passed in 1878 and the British Dental Association formed in 1879. In the same year, Francis Brodie Imlach was the first ever dentist to be elected President of

1936-529: A single field and includes three frequency-modulated waveforms: the luminance information, and red (R-Y) and blue (B-Y) color difference chrominance signals. Luminance is recorded between 6 MHz and 7.5 MHz (white peak); the R-Y signal has a center band of 1.2 MHz with a 0.7 MHz bandwidth and the B-Y signal has a center band of 1.3 MHz with a 0.5 MHz bandwidth. The Hi-Band format developed in 1988 shifts

2057-475: A wideband receiver. The main audio carrier is 4.5 MHz above the video carrier, making it 250 kHz below the top of the channel. Sometimes a channel may contain an MTS signal, which offers more than one audio signal by adding one or two subcarriers on the audio signal, each synchronized to a multiple of the line frequency. This is normally the case when stereo audio and/or second audio program signals are used. The same extensions are used in ATSC , where

2178-485: Is 3.579545 MHz above the video carrier, and is quadrature-amplitude-modulated with a suppressed carrier. The audio signal is frequency-modulated , like the audio signals broadcast by FM radio stations in the 88–108 MHz band, but with a 25 kHz maximum frequency deviation , as opposed to 75 kHz as is used on the FM band , making analog television audio signals sound quieter than FM radio signals as received on

2299-432: Is 60 μm (0.0024 in) wide with a track-to-track pitch of 100 μm (0.0039 in); the second track is recorded inboard of the first at a radius of 19.9 mm (0.78 in), and so on until the 52nd track is encoded with a radius of 14.7 mm (0.58 in). Track 51 is reserved as blank (without information), and Track 52 is used for a control signal. The analog signal recorded to each track corresponds to

2420-476: Is a 4° gap to afford margin against overwriting the succeeding (or preceding) block, followed by a 1° interval reserved for a burst signal that states the recording density and indicates the disk is encoded with digital data. After the burst signal, a 64-bit index signal is used to record the data address (track and block information) along with a checksum signal. The remainder of the block is formatted into 128 distinct frames, each capable of recording 32 bytes, making

2541-461: Is a movement in modern dentistry to place a greater emphasis on high-quality scientific evidence in decision-making. Evidence-based dentistry (EBD) uses current scientific evidence to guide decisions. It is an approach to oral health that requires the application and examination of relevant scientific data related to the patient's oral and medical health. Along with the dentist's professional skill and expertise, EBD allows dentists to stay up to date on

SECTION 20

#1733085254466

2662-401: Is added to the composite baseband signal (video plus audio and data subcarriers) before modulation. This limits the satellite downlink power spectral density in case the video signal is lost. Otherwise the satellite might transmit all of its power on a single frequency, interfering with terrestrial microwave links in the same frequency band. In half transponder mode, the frequency deviation of

2783-455: Is called a dentist . The history of dentistry is almost as ancient as the history of humanity and civilization, with the earliest evidence dating from 7000 BC to 5500 BC. Dentistry is thought to have been the first specialization in medicine which has gone on to develop its own accredited degree with its own specializations. Dentistry is often also understood to subsume the now largely defunct medical specialty of stomatology (the study of

2904-411: Is composed of two fields, each consisting of 262.5 scan lines, for a total of 525 scan lines. The visible raster is made up of 486 scan lines. The later digital standard, Rec. 601 , only uses 480 of these lines for visible raster. The remainder (the vertical blanking interval ) allow for vertical synchronization and retrace. This blanking interval was originally designed to simply blank

3025-418: Is designed to excite only the corresponding red, green, or blue phosphor dots. TV sets with digital circuitry use sampling techniques to process the signals but the result is the same. For both analog and digital sets processing an analog NTSC signal, the original three color signals are transmitted using three discrete signals (Y, I and Q) and then recovered as three separate colors (R, G, and B) and presented as

3146-701: Is duplicated and then the resulting stream is interlaced. Film shot for NTSC television at 24 frames per second has traditionally been accelerated by 1/24 (to about 104.17% of normal speed) for transmission in regions that use 25-fps television standards. This increase in picture speed has traditionally been accompanied by a similar increase in the pitch and tempo of the audio. More recently, frame-blending has been used to convert 24 FPS video to 25 FPS without altering its speed. Film shot for television in regions that use 25-fps television standards can be handled in either of two ways: Because both film speeds have been used in 25-fps regions, viewers can face confusion about

3267-490: Is equivalent to NTSC is 720 × 480 pixels. The digital television (DTV) equivalent is 704 × 480 pixels. The National Television System Committee was established in 1940 by the United States Federal Communications Commission (FCC) to resolve the conflicts between companies over the introduction of a nationwide analog television system in the United States. In March 1941,

3388-698: Is exposed to sound levels above 90 dBA according to the Occupational Safety and Health Administration (OSHA). Regulations state that the permissible noise exposure levels for individuals is 90 dBA. For the National Institute for Occupational Safety and Health ( NIOSH ), exposure limits are set to 85 dBA. Exposures below 85 dBA are not considered to be hazardous. Time limits are placed on how long an individual can stay in an environment above 85 dBA before it causes hearing loss. OSHA places that limitation at 8 hours for 85 dBA. The exposure time becomes shorter as

3509-601: Is part of the larger movement toward evidence-based medicine and other evidence-based practices , especially since a major part of dentistry involves dealing with oral and systemic diseases. Other issues relevant to the dental field in terms of evidence-based research and evidence-based practice include population oral health, dental clinical practice, tooth morphology etc. Dentistry is unique in that it requires dental students to have competence-based clinical skills that can only be acquired through supervised specialized laboratory training and direct patient care. This necessitates

3630-781: Is referred to as "oral-systemic health". John M. Harris started the world's first dental school in Bainbridge, Ohio , and helped to establish dentistry as a health profession. It opened on 21 February 1828, and today is a dental museum . The first dental college, Baltimore College of Dental Surgery , opened in Baltimore, Maryland, US in 1840. The second in the United States was the Ohio College of Dental Surgery , established in Cincinnati, Ohio, in 1845. The Philadelphia College of Dental Surgery followed in 1852. In 1907, Temple University accepted

3751-443: Is severely limited, analog video transmission through satellites differs from terrestrial TV transmission. AM is a linear modulation method, so a given demodulated signal-to-noise ratio (SNR) requires an equally high received RF SNR. The SNR of studio quality video is over 50 dB, so AM would require prohibitively high powers and/or large antennas. Wideband FM is used instead to trade RF bandwidth for reduced power. Increasing

Video Floppy - Misplaced Pages Continue

3872-613: Is sometimes called NTSC II. The only other broadcast television system to use NTSC color was the System J . Brazil used System M with PAL color. Vietnam, Cambodia and Laos used System M with SECAM color - Vietnam later started using PAL in the early 1990s. The NTSC/System M standard was used in most of the Americas (except Argentina , Brazil , Paraguay , and Uruguay ), Myanmar , South Korea , Taiwan , Philippines , Japan , and some Pacific Islands nations and territories (see map). Since

3993-446: Is the branch of medicine focused on the teeth , gums , and mouth . It consists of the study, diagnosis , prevention, management, and treatment of diseases , disorders, and conditions of the mouth, most commonly focused on dentition (the development and arrangement of teeth) as well as the oral mucosa . Dentistry may also encompass other aspects of the craniofacial complex including the temporomandibular joint . The practitioner

4114-628: Is transmitted for two video fields (lasting 1 video frame). Two film frames are thus transmitted in five video fields, for an average of 2 + 1 ⁄ 2  video fields per film frame. The average frame rate is thus 60 ÷ 2.5 = 24 frames per second, so the average film speed is nominally exactly what it should be. (In reality, over the course of an hour of real time, 215,827.2 video fields are displayed, representing 86,330.88 frames of film, while in an hour of true 24-fps film projection, exactly 86,400 frames are shown: thus, 29.97-fps NTSC transmission of 24-fps film runs at 99.92% of

4235-410: The Q ′ {\displaystyle Q^{\prime }} signal encodes purple-green color information at 0.4 MHz bandwidth; this allows the chrominance signal to use less overall bandwidth without noticeable color degradation. The two signals each amplitude modulate 3.58 MHz carriers which are 90 degrees out of phase with each other and the result added together but with

4356-513: The Y ′ {\displaystyle Y^{\prime }} signal, is reconstructed to the individual R ′ G ′ B ′ {\displaystyle R^{\prime }G^{\prime }B^{\prime }} signals, that are then sent to the CRT to form the image. In CRT televisions, the NTSC signal is turned into three color signals: red, green, and blue, each controlling an electron gun that

4477-599: The Americas and Japan . With the advent of digital television , analog broadcasts were largely phased out. Most US NTSC broadcasters were required by the FCC to shut down their analog transmitters by February 17, 2009, however this was later moved to June 12, 2009. Low-power stations , Class A stations and translators were required to shut down by 2015, although an FCC extension allowed some of those stations operating on Channel 6 to operate until July 13, 2021. The remaining Canadian analog TV transmitters, in markets not subject to

4598-749: The Mavipak name in 1981 for their prototype Mavica (not to be confused with their later line of Mavica digital cameras introduced in the mid-1990s, which stored JPEG images to standard 3.5-inch floppy disks readable by computers instead). The video floppy specification was proposed by the Electronic Still Camera Conference in 1985 and established as Standard CP-3901 (formerly CPZ-250) of the Electronic Industries Association of Japan (EIAJ) in September 1988. The video floppy format

4719-492: The carriers themselves being suppressed . The result can be viewed as a single sine wave with varying phase relative to a reference carrier and with varying amplitude. The varying phase represents the instantaneous color hue captured by a TV camera, and the amplitude represents the instantaneous color saturation . The 3.579545 MHz subcarrier is then added to the Luminance to form the composite color signal which modulates

4840-485: The 14th century, Guy de Chauliac most probably invented the dental pelican (resembling a pelican 's beak) which was used to perform dental extractions up until the late 18th century. The pelican was replaced by the dental key which, in turn, was replaced by modern forceps in the 19th century. The first book focused solely on dentistry was the "Artzney Buchlein" in 1530, and the first dental textbook written in English

4961-500: The 200, 300, 1000, 575, and 2000. A similarly sized disk was also used by the Zenith MinisPort laptop computer from 1989, digitally formatted for data storage. The MinisPort could store up to 793 KB of information on 2-inch LT format disks called LT-1 . Video floppy and LT-1 are neither physically nor digitally compatible, so media can not be interchanged between drives using video floppy or LT standards. An enhanced version of

Video Floppy - Misplaced Pages Continue

5082-522: The 5th century BC. The Phoenicians crafted dentures during the 6th–4th century BC, fashioning them from gold wire and incorporating two ivory teeth. In ancient Egypt, Hesy-Ra is the first named "dentist" (greatest of the teeth). The Egyptians bound replacement teeth together with gold wire. Roman medical writer Cornelius Celsus wrote extensively of oral diseases as well as dental treatments such as narcotic-containing emollients and astringents . The earliest dental amalgams were first documented in

5203-552: The ATSC digital carrier is broadcast at 0.31 MHz above the lower bound of the channel. "Setup" is a 54 mV (7.5  IRE ) voltage offset between the "black" and "blanking" levels. It is unique to NTSC. CVBS stands for Color, Video, Blanking, and Sync. The following table shows the values for the basic RGB colors, encoded in NTSC There is a large difference in frame rate between film, which runs at 24 frames per second, and

5324-464: The Diseases but of single Parts, it must needs be a barren Profession to confine unto that of drawing of Teeth, and little better than to have been Tooth-drawer unto King Pyrrhus, who had but two in his Head. The French surgeon Pierre Fauchard became known as the "father of modern dentistry". Despite the limitations of the primitive surgical instruments during the late 17th and early 18th century, Fauchard

5445-888: The European Broadcasting Union (EBU) rejected color correction in receivers and studio monitors that year and instead explicitly called for all equipment to directly encode signals for the "EBU" colorimetric values. In reference to the gamuts shown on the CIE chromaticity diagram (above), the variations between the different colorimetries can result in significant visual differences. To adjust for proper viewing requires gamut mapping via LUTs or additional color grading . SMPTE Recommended Practice RP 167-1995 refers to such an automatic correction as an "NTSC corrective display matrix." For instance, material prepared for 1953 NTSC may look desaturated when displayed on SMPTE C or ATSC/ BT.709 displays, and may also exhibit noticeable hue shifts. On

5566-613: The French and Latin words for tooth. The term for the associated scientific study of teeth is odontology (from Ancient Greek : ὀδούς , romanized :  odoús , lit.   'tooth') – the study of the structure, development, and abnormalities of the teeth. Dentistry usually encompasses practices related to the oral cavity. According to the World Health Organization , oral diseases are major public health problems due to their high incidence and prevalence across

5687-431: The NTSC color standard, which was cooperatively developed by several companies, including RCA and Philco. In December 1953, the FCC unanimously approved what is now called the NTSC color television standard (later defined as RS-170a). The compatible color standard retained full backward compatibility with then-existing black-and-white television sets. Color information was added to the black-and-white image by introducing

5808-485: The NTSC standard, as well as those using other analog television standards , have switched to, or are in process of switching to, newer digital television standards, with there being at least four different standards in use around the world. North America, parts of Central America , and South Korea are adopting or have adopted the ATSC standards, while other countries, such as Japan , are adopting or have adopted other standards instead of ATSC. After nearly 70 years,

5929-402: The NTSC standard, which runs at approximately 29.97 (10 MHz×63/88/455/525) frames per second. In regions that use 25-fps television and video standards, this difference can be overcome by speed-up . For 30-fps standards, a process called " 3:2 pulldown " is used. One film frame is transmitted for three video fields (lasting 1 + 1 ⁄ 2  video frames), and the next frame

6050-811: The Paleolithic, around 13,000 years ago, points to bitumen used to fill a tooth and in Neolithic Slovenia, 6500 years ago, beeswax was used to close a fracture in a tooth. The Indus valley has yielded evidence of dentistry being practised as far back as 7000 BC, during the Stone Age . The Neolithic site of Mehrgarh (now in Pakistan's south western province of Balochistan ) indicates that this form of dentistry involved curing tooth related disorders with bow drills operated, perhaps, by skilled bead-crafters. The reconstruction of this ancient form of dentistry showed that

6171-492: The Royal College of Surgeons (Edinburgh), raising dentistry onto a par with clinical surgery for the first time. Long term occupational noise exposure can contribute to permanent hearing loss, which is referred to as noise-induced hearing loss (NIHL) and tinnitus . Noise exposure can cause excessive stimulation of the hearing mechanism, which damages the delicate structures of the inner ear. NIHL can occur when an individual

SECTION 50

#1733085254466

6292-605: The UK than there were in 1921. It was between 1650 and 1800 that the science of modern dentistry developed. The English physician Thomas Browne in his A Letter to a Friend ( c.  1656 pub. 1690) made an early dental observation with characteristic humour: The Egyptian Mummies that I have seen, have had their Mouths open, and somewhat gaping, which affordeth a good opportunity to view and observe their Teeth, wherein 'tis not easie to find any wanting or decayed: and therefore in Egypt, where one Man practised but one Operation, or

6413-787: The United Kingdom became fully regulated with the 1921 Dentists Act, which required the registration of anyone practising dentistry. The British Dental Association , formed in 1880 with Sir John Tomes as president, played a major role in prosecuting dentists practising illegally. Dentists in the United Kingdom are now regulated by the General Dental Council . In many countries, dentists usually complete between five and eight years of post-secondary education before practising. Though not mandatory, many dentists choose to complete an internship or residency focusing on specific aspects of dental care after they have received their dental degree. In

6534-615: The United Kingdom, the first dental schools, the London School of Dental Surgery and the Metropolitan School of Dental Science, both in London, opened in 1859. The British Dentists Act of 1878 and the 1879 Dentists Register limited the title of "dentist" and "dental surgeon" to qualified and registered practitioners. However, others could legally describe themselves as "dental experts" or "dental consultants". The practice of dentistry in

6655-773: The United States undergo at least three years of undergraduate studies, but nearly all complete a bachelor's degree. This schooling is followed by four years of dental school to qualify as a " Doctor of Dental Surgery " (DDS) or " Doctor of Dental Medicine " (DMD). Specialization in dentistry is available in the fields of Anesthesiology, Dental Public Health, Endodontics, Oral Radiology, Oral and Maxillofacial Surgery, Oral Medicine, Orofacial Pain, Pathology, Orthodontics, Pediatric Dentistry (Pedodontics), Periodontics, and Prosthodontics. Some dentists undertake further training after their initial degree in order to specialize. Exactly which subjects are recognized by dental registration bodies varies according to location. Examples include: Tooth decay

6776-461: The VF format called Hi-VF was introduced in the late 1980s, providing higher resolution per video still than its predecessor. It used higher-bandwidth video recording, much like S-VHS as compared to VHS , or Hi8 compared to Video 8 . NTSC NTSC (from National Television System Committee ) is the first American standard for analog television , published and adopted in 1941. In 1961, it

6897-546: The air and through cable, but also in the home-video market, on both tape and disc, including laser disc and DVD . In digital television and video, which are replacing their analog predecessors, single standards that can accommodate a wider range of frame rates still show the limits of analog regional standards. The initial version of the ATSC standard, for example, allowed frame rates of 23.976, 24, 29.97, 30, 59.94, 60, 119.88 and 120 frames per second, but not 25 and 50. Modern ATSC allows 25 and 50 FPS. Because satellite power

7018-420: The audio subcarrier frequency or lower the line frequency. Raising the audio subcarrier frequency would prevent existing (black and white) receivers from properly tuning in the audio signal. Lowering the line frequency is comparatively innocuous, because the horizontal and vertical synchronization information in the NTSC signal allows a receiver to tolerate a substantial amount of variation in the line frequency. So

7139-426: The blue difference signal is B ′ − Y ′ {\displaystyle B^{\prime }-Y^{\prime }} . These difference signals are then used to derive two new color signals known as I ′ {\displaystyle I^{\prime }} (in-phase) and Q ′ {\displaystyle Q^{\prime }} (in quadrature) in

7260-448: The camera shutter from the video signal itself. The actual figure of 525 lines was chosen as a consequence of the limitations of the vacuum-tube-based technologies of the day. In early TV systems, a master voltage-controlled oscillator was run at twice the horizontal line frequency, and this frequency was divided down by the number of lines used (in this case 525) to give the field frequency (60 Hz in this case). This frequency

7381-427: The cartridge is equipped with a sliding shutter for dust protection and a hub opening that is 15.9 mm (0.63 in) in diameter. The magnetic disc is divided into 52 coaxial tracks and rotates at either 3600 RPM to match the NTSC video field frequency (60 fields/second) or 3000 RPM for PAL and SECAM (50 fields/second) instead. The first track is encoded with a radius of 20 mm (0.79 in); each track

SECTION 60

#1733085254466

7502-498: The chances of a successful tooth transplant (initially, at least) would be improved if the donor tooth was as fresh as possible and was matched for size with the recipient. These principles are still used in the transplantation of internal organs . Hunter conducted a series of pioneering operations, in which he attempted a tooth transplant. Although the donated teeth never properly bonded with the recipients' gums, one of Hunter's patients stated that he had three which lasted for six years,

7623-601: The channel bandwidth from 6 to 36 MHz allows a RF SNR of only 10 dB or less. The wider noise bandwidth reduces this 40 dB power saving by 36 MHz / 6 MHz = 8 dB for a substantial net reduction of 32 dB. Sound is on an FM subcarrier as in terrestrial transmission, but frequencies above 4.5 MHz are used to reduce aural/visual interference. 6.8, 5.8 and 6.2 MHz are commonly used. Stereo can be multiplex, discrete, or matrix and unrelated audio and data signals may be placed on additional subcarriers. A triangular 60 Hz energy dispersal waveform

7744-525: The chrominance signal. (Another way this is often stated is that the color subcarrier frequency is an odd multiple of half the line frequency.) They then chose to make the audio subcarrier frequency an integer multiple of the line frequency to minimize visible (intermodulation) interference between the audio signal and the chrominance signal. The original black-and-white standard, with its 15,750 Hz line frequency and 4.5 MHz audio subcarrier, does not meet these requirements, so designers had to either raise

7865-550: The committee issued a technical standard for black-and-white television that built upon a 1936 recommendation made by the Radio Manufacturers Association (RMA). Technical advancements of the vestigial side band technique allowed for the opportunity to increase the image resolution. The NTSC selected 525 scan lines as a compromise between RCA 's 441-scan line standard (already being used by RCA's NBC TV network) and Philco 's and DuMont 's desire to increase

7986-571: The committee was reconstituted to standardize color television . The FCC had briefly approved a 405-line field-sequential color television standard in October 1950, which was developed by CBS . The CBS system was incompatible with existing black-and-white receivers. It used a rotating color wheel, reduced the number of scan lines from 525 to 405, and increased the field rate from 60 to 144, but had an effective frame rate of only 24 frames per second. Legal action by rival RCA kept commercial use of

8107-566: The composite baseband signal is reduced to 18 MHz to allow another signal in the other half of the 36 MHz transponder. This reduces the FM benefit somewhat, and the recovered SNRs are further reduced because the combined signal power must be "backed off" to avoid intermodulation distortion in the satellite transponder. A single FM signal is constant amplitude, so it can saturate a transponder without distortion. Dentistry Dentistry , also known as dental medicine and oral medicine ,

8228-558: The country. The first color NTSC television camera was the RCA TK-40 , used for experimental broadcasts in 1953; an improved version, the TK-40A, introduced in March 1954, was the first commercially available color television camera. Later that year, the improved TK-41 became the standard camera used throughout much of the 1960s. The NTSC standard has been adopted by other countries, including some in

8349-455: The dBA level increases. Within the field of dentistry, a variety of cleaning tools are used including piezoelectric and sonic scalers, and ultrasonic scalers and cleaners. While a majority of the tools do not exceed 75 dBA, prolonged exposure over many years can lead to hearing loss or complaints of tinnitus. Few dentists have reported using personal hearing protective devices, which could offset any potential hearing loss or tinnitus. There

8470-472: The display, etc. Over its history, NTSC color had two distinctly defined colorimetries, shown on the accompanying chromaticity diagram as NTSC 1953 and SMPTE C. Manufacturers introduced a number of variations for technical, economic, marketing, and other reasons. The original 1953 color NTSC specification, still part of the United States Code of Federal Regulations , defined the colorimetric values of

8591-462: The early B&W sets did not do this and chrominance could be seen as a crawling dot pattern in areas of the picture that held saturated colors. To derive the separate signals containing only color information, the difference is determined between each color primary and the summed luma. Thus the red difference signal is R ′ − Y ′ {\displaystyle R^{\prime }-Y^{\prime }} and

8712-405: The electron beam of the receiver's CRT to allow for the simple analog circuits and slow vertical retrace of early TV receivers. However, some of these lines may now contain other data such as closed captioning and vertical interval timecode (VITC). In the complete raster (disregarding half lines due to interlacing ) the even-numbered scan lines (every other line that would be even if counted in

8833-424: The end of 2016. Digital broadcasting allows higher-resolution television , but digital standard definition television continues to use the frame rate and number of lines of resolution established by the analog NTSC standard. NTSC color encoding is used with the System M television signal, which consists of 30 ⁄ 1.001  (approximately 29.97)  interlaced frames of video per second . Each frame

8954-417: The engineers chose the line frequency to be changed for the color standard. In the black-and-white standard, the ratio of audio subcarrier frequency to line frequency is 4.5 MHz ⁄ 15,750 Hz  = 285.71. In the color standard, this becomes rounded to the integer 286, which means the color standard's line rate is 4.5 MHz ⁄ 286  ≈ 15,734 Hz. Maintaining

9075-460: The eruption pattern of teeth, treating decayed teeth and gum disease, extracting teeth with forceps , and using wires to stabilize loose teeth and fractured jaws. Use of dental appliances, bridges and dentures was applied by the Etruscans in northern Italy, from as early as 700 BC, of human or other animal teeth fastened together with gold bands. The Romans had likely borrowed this technique by

9196-549: The film's normal speed.) Still-framing on playback can display a video frame with fields from two different film frames, so any difference between the frames will appear as a rapid back-and-forth flicker. There can also be noticeable jitter/"stutter" during slow camera pans ( telecine judder ). Film shot specifically for NTSC television is usually taken at 30 (instead of 24) frames per second to avoid 3:2 pulldown. To show 25-fps material (such as European television series and some European movies) on NTSC equipment, every fifth frame

9317-556: The formatted capacity of the Video Floppy 800 Kbytes (50 tracks × 4 blocks/track × 128 frames/block × 32 bytes/frame). The video floppy was used in multiple applications during the 1980s and 1990s. Many medical endoscopy and dentistry video systems, as well as industrial video borescopes & fiberscopes , used VF disks for storing video images for later playback and study. Standalone VF recorders & players were also used by television stations and video production studios as

9438-555: The globe, with the disadvantaged affected more than other socio-economic groups. The majority of dental treatments are carried out to prevent or treat the two most common oral diseases which are dental caries (tooth decay) and periodontal disease (gum disease or pyorrhea). Common treatments involve the restoration of teeth , extraction or surgical removal of teeth, scaling and root planing , endodontic root canal treatment, and cosmetic dentistry By nature of their general training, dentists, without specialization can carry out

9559-531: The introduction of digital sources (ex: DVD) the term NTSC has been used to refer to digital formats with number of active lines between 480 and 487 having 30 or 29.97 frames per second rate, serving as a digital shorthand to System M. The so-called NTSC-Film standard has a digital standard resolution of 720 × 480 pixel for DVD-Videos , 480 × 480 pixel for Super Video CDs (SVCD, Aspect Ratio: 4:3) and 352 × 240 pixel for Video CDs (VCD). The digital video (DV) camcorder format that

9680-531: The latest procedures and patients to receive improved treatment. A new paradigm for medical education designed to incorporate current research into education and practice was developed to help practitioners provide the best care for their patients. It was first introduced by Gordon Guyatt and the Evidence-Based Medicine Working Group at McMaster University in Ontario, Canada in the 1990s. It

9801-427: The lower bound of the channel. The video carrier is 1.25 MHz above the lower bound of the channel. Like most AM signals, the video carrier generates two sidebands , one above the carrier and one below. The sidebands are each 4.2 MHz wide. The entire upper sideband is transmitted, but only 1.25 MHz of the lower sideband, known as a vestigial sideband , is transmitted. The color subcarrier, as noted above,

9922-455: The luminance signal to between 7.7 and 9.7 MHz, improving the signal-to-noise ratio and resolution. The patent for the data variant of the Video Floppy was filed by Ken Kutaragi and assigned to Sony Corporation . This patent describes a formatting scheme that allows the disk to record digital data. In this scheme, each track is divided into 4 angular sectors known as blocks, with each block spanning an angle of 90°. Within each block, there

10043-584: The majority of dental treatments such as restorative (fillings, crowns , bridges ), prosthetic ( dentures ), endodontic (root canal) therapy, periodontal (gum) therapy, and extraction of teeth, as well as performing examinations, radiographs (x-rays), and diagnosis. Dentists can also prescribe medications used in the field such as antibiotics , sedatives , and any other drugs used in patient management. Depending on their licensing boards, general dentists may be required to complete additional training to perform sedation, dental implants, etc. Dentists also encourage

10164-704: The majority of over-the-air NTSC transmissions in the United States ceased on June 12, 2009, and by August 31, 2011, in Canada and most other NTSC markets. The majority of NTSC transmissions ended in Japan on July 24, 2011, with the Japanese prefectures of Iwate , Miyagi , and Fukushima ending the next year. After a pilot program in 2013, most full-power analog stations in Mexico left the air on ten dates in 2015, with some 500 low-power and repeater stations allowed to remain in analog until

10285-466: The mandatory transition in 2011, were scheduled to be shut down by January 14, 2022, under a schedule published by Innovation, Science and Economic Development Canada in 2017; however the scheduled transition dates have already passed for several stations listed that continue to broadcast in analog (e.g. CFJC-TV Kamloops, which has not yet transitioned to digital, is listed as having been required to transition by November 20, 2020). Most countries using

10406-565: The methods used were reliable and effective. The earliest dental filling , made of beeswax , was discovered in Slovenia and dates from 6500 years ago. Dentistry was practised in prehistoric Malta , as evidenced by a skull which had a dental abscess lanced from the root of a tooth dating back to around 2500 BC. An ancient Sumerian text describes a " tooth worm " as the cause of dental caries . Evidence of this belief has also been found in ancient India, Egypt , Japan, and China. The legend of

10527-405: The mouth and its disorders and diseases) for which reason the two terms are used interchangeably in certain regions. However, some specialties such as oral and maxillofacial surgery (facial reconstruction) may require both medical and dental degrees to accomplish. In European history, dentistry is considered to have stemmed from the trade of barber surgeons . Dental treatments are carried out by

10648-549: The nonlinear gamma corrected signals transmitted, the adjustment can only be approximated, introducing both hue and luminance errors for highly saturated colors. Similarly at the broadcaster stage, in 1968–69 the Conrac Corp., working with RCA, defined a set of controlled phosphors for use in broadcast color picture video monitors . This specification survives today as the SMPTE C phosphor specification: As with home receivers, it

10769-419: The number of scan lines to between 605 and 800. The standard recommended a frame rate of 30 frames (images) per second, consisting of two interlaced fields per frame at 262.5 lines per field and 60 fields per second. Other standards in the final recommendation were an aspect ratio of 4:3, and frequency modulation (FM) for the sound signal (which was quite new at the time). In January 1950,

10890-619: The occlusal guidance of the teeth; this principle is still valid in modern times. Al-Zahrawi invented over 200 surgical tools that resemble the modern kind. Historically, dental extractions have been used to treat a variety of illnesses. During the Middle Ages and throughout the 19th century, dentistry was not a profession in itself, and often dental procedures were performed by barbers or general physicians . Barbers usually limited their practice to extracting teeth which alleviated pain and associated chronic tooth infection . Instruments used for dental extractions date back several centuries. In

11011-515: The only practical method of frequency division was the use of a chain of vacuum tube multivibrators , the overall division ratio being the mathematical product of the division ratios of the chain. Since all the factors of an odd number also have to be odd numbers, it follows that all the dividers in the chain also had to divide by odd numbers, and these had to be relatively small due to the problems of thermal drift with vacuum tube devices. The closest practical sequence to 500 that meets these criteria

11132-449: The oral cavity. Other practices relevant to evidence-based dentistry include radiology of the mouth to inspect teeth deformity or oral malaises, haematology (study of blood) to avoid bleeding complications during dental surgery, cardiology (due to various severe complications arising from dental surgery with patients with heart disease), etc. The term dentistry comes from dentist , which comes from French dentiste , which comes from

11253-419: The original black-and-white system; when color was added to the system, however, the refresh frequency was shifted slightly downward by 0.1%, to approximately 59.94 Hz, to eliminate stationary dot patterns in the difference frequency between the sound and color carriers (as explained below in §   Color encoding ). By the time the frame rate changed to accommodate color, it was nearly as easy to trigger

11374-426: The other hand, SMPTE C materials may appear slightly more saturated on BT.709/sRGB displays, or significantly more saturated on P3 displays, if the appropriate gamut mapping is not performed. NTSC uses a luminance - chrominance encoding system, incorporating concepts invented in 1938 by Georges Valensi . Using a separate luminance signal maintained backward compatibility with black-and-white television sets in use at

11495-407: The place of the original monochrome signal . The color difference information is encoded into the chrominance signal, which carries only the color information. This allows black-and-white receivers to display NTSC color signals by simply ignoring the chrominance signal. Some black-and-white TVs sold in the U.S. after the introduction of color broadcasting in 1953 were designed to filter chroma out, but

11616-550: The prevention of oral diseases through proper hygiene and regular, twice or more yearly, checkups for professional cleaning and evaluation. Oral infections and inflammations may affect overall health and conditions in the oral cavity may be indicative of systemic diseases, such as osteoporosis , diabetes , celiac disease or cancer . Many studies have also shown that gum disease is associated with an increased risk of diabetes, heart disease , and preterm birth . The concept that oral health can affect systemic health and disease

11737-400: The resulting pattern less noticeable, designers adjusted the original 15,750 Hz scanline rate down by a factor of 1.001 (0.1%) to match the audio carrier frequency divided by the factor 286, resulting in a field rate of approximately 59.94 Hz. This adjustment ensures that the difference between the sound carrier and the color subcarrier (the most problematic intermodulation product of

11858-441: The same number of scan lines per field (and frame), the lower line rate must yield a lower field rate. Dividing 4500000 ⁄ 286 lines per second by 262.5 lines per field gives approximately 59.94 fields per second. An NTSC television channel as transmitted occupies a total bandwidth of 6 MHz. The actual video signal, which is amplitude-modulated , is transmitted between 500  kHz and 5.45 MHz above

11979-415: The screen. Synchronization of the refresh rate to the power incidentally helped kinescope cameras record early live television broadcasts, as it was very simple to synchronize a film camera to capture one frame of video on each film frame by using the alternating current frequency to set the speed of the synchronous AC motor-drive camera. This, as mentioned, is how the NTSC field refresh frequency worked in

12100-436: The standard at both the receiver and broadcaster was the source of considerable color variation. To ensure more uniform color reproduction, some manufacturers incorporated color correction circuits into sets, that converted the received signal—encoded for the colorimetric values listed above—adjusting for the actual phosphor characteristics used within the monitor. Since such color correction can not be performed accurately on

12221-592: The system as shown in the above table. Early color television receivers, such as the RCA CT-100 , were faithful to this specification (which was based on prevailing motion picture standards), having a larger gamut than most of today's monitors. Their low-efficiency phosphors (notably in the Red) were weak and long-persistent, leaving trails after moving objects. Starting in the late 1950s, picture tube phosphors would sacrifice saturation for increased brightness; this deviation from

12342-578: The system off the air until June 1951, and regular broadcasts only lasted a few months before manufacture of all color television sets was banned by the Office of Defense Mobilization in October, ostensibly due to the Korean War . A variant of the CBS system was later used by NASA to broadcast pictures of astronauts from space. CBS rescinded its system in March 1953, and the FCC replaced it on December 17, 1953, with

12463-405: The teeth and in the gums could appear in the later stages of tooth decay. Fauchard was the pioneer of dental prosthesis , and he invented many methods to replace lost teeth. He suggested that substitutes could be made from carved blocks of ivory or bone . He also introduced dental braces , although they were initially made of gold, he discovered that the teeth position could be corrected as

12584-433: The teeth would follow the pattern of the wires. Waxed linen or silk threads were usually employed to fasten the braces. His contributions to the world of dental science consist primarily of his 1728 publication Le chirurgien dentiste or The Surgeon Dentist. The French text included "basic oral anatomy and function, dental construction, and various operative and restorative techniques, and effectively separated dentistry from

12705-658: The time the color standard was promulgated, the color subcarrier frequency was constructed as composite frequency assembled from small integers, in this case 5×7×9/(8×11) MHz. The horizontal line rate was reduced to approximately 15,734 lines per second (3.579545×2/455 MHz = 9/572 MHz) from 15,750 lines per second, and the frame rate was reduced to 30/1.001 ≈ 29.970 frames per second (the horizontal line rate divided by 525 lines/frame) from 30 frames per second. These changes amounted to 0.1 percent and were readily tolerated by then-existing television receivers. The first publicly announced network television broadcast of

12826-491: The time; only color sets would recognize the chroma signal, which was essentially ignored by black and white sets. The red, green, and blue primary color signals ( R ′ G ′ B ′ ) {\displaystyle (R^{\prime }G^{\prime }B^{\prime })} are weighted and summed into a single luma signal, designated Y ′ {\displaystyle Y^{\prime }} (Y prime) which takes

12947-510: The treatment of dislocated or fractured jaws. In the 18th century BC, the Code of Hammurabi referenced dental extraction twice as it related to punishment. Examination of the remains of some ancient Egyptians and Greco-Romans reveals early attempts at dental prosthetics . However, it is possible the prosthetics were prepared after death for aesthetic reasons. Ancient Greek scholars Hippocrates and Aristotle wrote about dentistry, including

13068-591: The true speed of video and audio, and the pitch of voices, sound effects, and musical performances, in television films from those regions. For example, they may wonder whether the Jeremy Brett series of Sherlock Holmes television films, made in the 1980s and early 1990s, was shot at 24 fps and then transmitted at an artificially fast speed in 25-fps regions, or whether it was shot at 25 fps natively and then slowed to 24 fps for NTSC exhibition. These discrepancies exist not only in television broadcasts over

13189-409: The two carriers) is an odd multiple of half the line rate, which is the necessary condition for the dots on successive lines to be opposite in phase, making them least noticeable. The 59.94 rate is derived from the following calculations. Designers chose to make the chrominance subcarrier frequency an n + 0.5 multiple of the line frequency to minimize interference between the luminance signal and

13310-449: The video signal carrier . 3.58 MHz is often stated as an abbreviation instead of 3.579545 MHz. For a color TV to recover hue information from the color subcarrier, it must have a zero-phase reference to replace the previously suppressed carrier. The NTSC signal includes a short sample of this reference signal, known as the colorburst , located on the back porch of each horizontal synchronization pulse. The color burst consists of

13431-466: The video signal, e.g. {2, 4, 6, ..., 524}) are drawn in the first field, and the odd-numbered (every other line that would be odd if counted in the video signal, e.g. {1, 3, 5, ..., 525}) are drawn in the second field, to yield a flicker-free image at the field refresh frequency of 60 ⁄ 1.001  Hz (approximately 59.94 Hz). For comparison, 625 lines (576 visible) systems, usually used with PAL-B/G and SECAM color, and so have

13552-573: The wider category of surgery". After Fauchard, the study of dentistry rapidly expanded. Two important books, Natural History of Human Teeth (1771) and Practical Treatise on the Diseases of the Teeth (1778), were published by British surgeon John Hunter . In 1763, he entered into a period of collaboration with the London-based dentist James Spence. He began to theorise about the possibility of tooth transplants from one person to another. He realised that

13673-662: The worm is also found in the Homeric Hymns , and as late as the 14th century AD the surgeon Guy de Chauliac still promoted the belief that worms cause tooth decay. Recipes for the treatment of toothache, infections and loose teeth are spread throughout the Ebers Papyrus , Kahun Papyri , Brugsch Papyrus , and Hearst papyrus of Ancient Egypt . The Edwin Smith Papyrus , written in the 17th century BC but which may reflect previous manuscripts from as early as 3000 BC, discusses

13794-409: Was 3×5×5×7=525 . (For the same reason, 625-line PAL-B/G and SECAM uses 5×5×5×5 , the old British 405-line system used 3×3×3×3×5 , the French 819-line system used 3×3×7×13 etc.) Colorimetry refers to the specific colorimetric characteristics of the system and its components, including the specific primary colors used, the camera,

13915-412: Was a highly skilled surgeon who made remarkable improvisations of dental instruments, often adapting tools from watchmakers , jewelers and even barbers , that he thought could be used in dentistry. He introduced dental fillings as treatment for dental cavities . He asserted that sugar -derived acids like tartaric acid were responsible for dental decay , and also suggested that tumors surrounding

14036-464: Was assigned the designation System M . It is also known as EIA standard 170. In 1953, a second NTSC standard was adopted, which allowed for color television broadcast compatible with the existing stock of black-and-white receivers. It is one of three major color formats for analog television, the others being PAL and SECAM . NTSC color is usually associated with the System M; this combination

14157-508: Was called "Operator for the Teeth" by Charles Allen in 1685. In the United Kingdom, there was no formal qualification for the providers of dental treatment until 1859 and it was only in 1921 that the practice of dentistry was limited to those who were professionally qualified. The Royal Commission on the National Health Service in 1979 reported that there were then more than twice as many registered dentists per 10,000 population in

14278-868: Was further recommended that studio monitors incorporate similar color correction circuits so that broadcasters would transmit pictures encoded for the original 1953 colorimetric values, in accordance with FCC standards. In 1987, the Society of Motion Picture and Television Engineers (SMPTE) Committee on Television Technology, Working Group on Studio Monitor Colorimetry, adopted the SMPTE C (Conrac) phosphors for general use in Recommended Practice 145, prompting many manufacturers to modify their camera designs to directly encode for SMPTE C colorimetry without color correction, as approved in SMPTE standard 170M, "Composite Analog Video Signal – NTSC for Studio Applications" (1994). As

14399-691: Was later used by Minolta , Panasonic , and Canon for their still video cameras introduced in the mid-to-late 1980s, such as the Canon Xapshot from 1988 (also known as the Canon Ion in Europe and the Canon Q-PIC in Japan). Besides still video cameras, stand-alone recorders & players were also available for the VF format, that could record from or output a composite video signal, to or from an external source (such as

14520-496: Was low in pre-agricultural societies, but the advent of farming society about 10,000 years ago correlated with an increase in tooth decay (cavities). An infected tooth from Italy partially cleaned with flint tools, between 13,820 and 14,160 years old, represents the oldest known dentistry, although a 2017 study suggests that 130,000 years ago the Neanderthals already used rudimentary dentistry tools. In Italy evidence dated to

14641-401: Was then compared with the 60 Hz power-line frequency and any discrepancy corrected by adjusting the frequency of the master oscillator. For interlaced scanning, an odd number of lines per frame was required in order to make the vertical retrace distance identical for the odd and even fields, which meant the master oscillator frequency had to be divided down by an odd number. At the time,

#465534