Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “light quality”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources

Toothbrush selection: a dilemma?

The toothbrush is a fundamental tool used for accomplishing plaque control. Various types of toothbrushes available in the market keep the buyer in a state of dilemma as to which one to choose, due to lack of information about the "quality" of it. This study has been designed to understand whether all the products available in the market adhere to the specifications laid down by the ADA, which is universally accepted in standardization of a tooth brush. 95% of the brushes surveyed contain less number of bristles per tuft than specified and a large percentage deviate from the standard prescribed value for their bristle diameter and other dimensions. Few brushes labeled as "Soft" were "Medium" and labeled "Medium" were "Hard". The study will bring to light the quality of toothbrushes available in India for a rationalised selection of appropriate toothbrush by the community at large.

American Dental Association↗

[Quality control of film viewing boxes].

Film inspection boxes have been examined in order to find out whether the introduction of the Roentgen regulation has led to positive results with regard to amount, illuminating density and homogeneity. In comparison to former results which have been published, it seems that the illuminating density is still too low. On the average, we found a value of 1.700 cd/m2.

Germany↗

Employment status and perceptions of control of adults with cognitive and developmental disabilities.

This study was designed to examine the relationship between individual perceptions of control and employment status among adults with cognitive and developmental disabilities. The literature implies that one factor influencing perceptions of quality of life is the amount of control the person experiences across various domains. It was hypothesized that individuals employed in competitive work situations would evidence more positive perceptions of control than would their peers currently unemployed or employed in sheltered settings. Surveys containing the Adult version of the Nowicki-Strickland Internal-External Scale and requesting information about age, gender, and employment status were mailed to self-advocacy groups. For the more than 200 respondents, there were significant differences in locus of control scores among individuals employed competitively, individuals employed full-time, respondents in sheltered environments, individuals currently unemployed, and all other groups. Individuals unemployed and employed in sheltered settings perceived themselves as having less control than individuals employed competitively. These results are examined in light of quality of life findings, focusing on the need to include choice and control in programming for people with cognitive and developmental disabilities.

Adult↗

Microscope-assisted precision dentistry.

To enhance their vision for both clinical and laboratory procedures, an increasing number of dental practitioners are introducing magnification into their practices. Most are using either simple or compound loupes mounted on glasses frames. And although magnification is not new to dentistry, it is a trend that is gaining a broader acceptance among both seasoned practitioners and recent graduates. Many dental schools are allowing their students to use loupes on a discretionary basis, so the notion that magnification is reserved only to compensate for deteriorating vision is rapidly disappearing. Dental professionals have also begun to recognize that the quantity and quality of light in the working field is just as important as magnification. Headlamps with focused, color-correct light sources in combination with loupes are becoming popular. It is highly unlikely that a practitioner using loupes would relinquish them and return to practicing without magnification. The newest addition to the vision enhancement arena in dentistry is the operating microscope. In some medical subspecialties--such as otolaryngology, ophthalmology, plastic surgery, and neurosurgery--extensive microsurgical training is required to perform procedures at acceptable standards of precision. In 1998, the American Association of Endodontists (AAE) elected to mandate that all endodontic postgraduate students demonstrate proficiency using an operating microscope before they receive their certificates. Microscope use has also been reported in periodontics. For several decades, many dental laboratory technicians have used stereomicroscopes for trimming dies, refining castings, and performing other procedures that require a high degree of precision. However, according to microscope manufacturers, most current instrument sales are to general practitioners, who are not limiting the use of their microscopes to endodontic therapy--they are using them for a wide variety of procedures. Microscopes have the potential to enhance a dental practitioner's vision to unprecedented levels, but there are some practical questions that need to be addressed. What kind of visual acuity do dentists really need to perform high-quality dentistry? If a dentist wants to improve his or her vision, do loupes provide an adequate level of magnification? Is using a microscope too complicated for restorative and prosthodontic procedures, and how long does it take to become proficient with a microscope? These are some of the questions I posed to two outstanding dentists who have had extensive clinical experience using surgical microscopes. I also share my own experience with a microscope.

Dental Equipment↗

Efficacy of acitretin and commercial tanning bed therapy for psoriasis.

OBJECTIVE: To assess the efficacy of acitretin and commercial tanning bed therapy for the treatment of moderate to severe chronic plaque-type psoriasis. DESIGN: Retrospective medical record review and telephone survey of subjects and prospective open-label trial. SETTING: University dermatology clinic. PATIENTS: The study population comprised 26 subjects in the retrospective study and 17 subjects in the prospective study, all with moderate to severe plaque-type psoriasis. INTERVENTION: Twelve weeks of daily oral acitretin (25 mg) therapy and commercial tanning bed UV exposure (mean UV-B output of 4.7%) for 4 to 5 days per week. RESULTS: In the retrospective review, 19 (83%) of 23 subjects had clearance or near clearance, 2 (9%) of 23 had moderate improvement, and 2 (9%) of 23 had no improvement. Patients reported a high degree of satisfaction with the treatment. In the prospective trial, the Psoriasis Area and Severity Index (PASI) and National Psoriasis Foundation scores decreased an average of 78.6% and 79.0% from baseline, respectively. A reduction from baseline in the PASI score of 50% and 75% (PASI 50 and PASI 75) was achieved by 13 (76%) and 10 (59%) patients, respectively. Adverse events were generally mild to moderate. CONCLUSIONS: Acitretin use in combination with commercial tanning bed therapy appears to be effective and useful for psoriasis in areas without access to physician-directed phototherapy. The variability of tanning salon light and quality mandates caution when using this therapy.

Acitretin↗

Degenerative changes in retinal vessels. Photodocumentation with monochromatic filters.

The appearance of certain ocular structure changes due to changes in absorption, reflection, and optical transmission depends on the wavelength of light. By means of this physical quality of the light, it is possible to demonstrate certain parts of the fundus better than others. Several examples described in this article demonstrate how degenerative vascular alterations can be judged much better and more safely by use of monochromatic light and light of varying wavelengths. Alterations of blood vessel caliber show the most contrast in yellow-green light where there is maximum absorption by the blood. Alterations in blood vessel wall reflection that are invisible in white light can be demonstrated in short-wave light and also partially in red light. Ophthalmoscopy in connection with the xenon arc lamp as a method of examination is suprior to photography alone.

Color↗

Verbal behavior and schizophrenia. The semantic dimension.

Through the use of computer analysis, the content of the speech of schizophrenics is shown to be distinct from that of the speech of nonschizophrenic psychiatric patients. The data shed light on qualities that delineate some aspects of "bizarreness" in speech of schizophrenics, provide some insight into the diversity of postulated "defects" in schizophrenic thinking, and provide further understanding of the diagnostic process in schizophrenia.

Adult↗

Work environment effects on labor productivity: an intervention study in a storage building.

BACKGROUND: Although increased attention has been focused on the relationship between occupational health and productivity, solid scientific data on this topic are sparse. The purpose of the present case study was to assess the relationship between productivity and work environment in a storage building. MATERIALS AND METHODS: The study was implemented as an intervention consisting of the renovation of a harbor storage facility. The study design consisted of a single group of employees working in the storage hall. The physical and chemical factors, perceived environment, and labor productivity were measured before and after the renovation. RESULTS: As a result of the renovation, thermal conditions, air quality, and lighting conditions improved notably. In addition, the employees' subjective evaluations showed the significant decrease in dissatisfaction ratings. The direct measure for the labor productivity, expressed as zinc tons/work-hour (tn) increased about 9% after the renovation. DISCUSSION: We conclude that increased productivity is most likely related to the combined effect of the improved work environment, i.e., better thermal climate, reduced contaminant concentrations, and better lighting conditions.

Adult↗

A modular detector for flow cytometric multicolor fluorescence measurements.

A modular detector for measuring multicolor fluorescence from cells illuminated by single or multiple lasers has been developed for flow cytometers. Motion picture projector, camera, and CCTV/video lenses were evaluated for use in the detector by comparing their physical characteristics, image quality, and light collection efficiencies. A 25-mm focal length F/0.95 CCTV lens was selected, based on our criteria and test results. The detector was constructed out of square aluminum extrusion channels. A CCTV lens mounted on the outside of the first channel collected light emitted from cells and collimated it towards filters and secondary CCTV lenses located in each channel. The secondary lenses functioned as relay optics for directing and focusing light onto pinhole spatial filters for measurement by photomultipliers. The detector design allowed any number of channels to be connected together and the versatility for making simultaneous or sequential measurements. Measurements on lymphocytes labeled with four monoclonal antibodies conjugated to fluorescent dyes and measurements on viable tumor cells stained for DNA content and with three fluorescent-labeled antibodies were used to demonstrate the detector's capabilities.

Animals↗

Complementary chromatic adaptation: photoperception to gene regulation.

Many photosynthetic organisms can acclimate to the quantity and quality of light present in their environment. In certain cyanobacteria the wavelengths of light in the environment control the synthesis of specific polypeptides of the light harvesting antenna complex or phycobilisome. This phenomenon, called complementary chromatic adaptation, is most dramatically observed in a comparison of cyanobacteria after growth in green light and red light. In red light-grown cells the phycobilisome is largely composed of phycocyanin and its associated linker polypeptides (the latter are important for the assembly of the phycocyanin subunits and their placement within the light harvesting structure); the organisms appear blue-green in color. In green light-grown cells the phycobilisome is largely composed of phycoerythrin and its associated linker polypeptides; the organisms appear red in color. The ways in which these cyanobacteria sense their changing light environment and the regulatory elements involved in controlling the process of complementary chromatic adaptation are discussed in this review.

Adaptation, Physiological↗

[Hyalinizing clear cell carcinoma of the salivary glands].

Many cell types of the salivary glands have clear cytoplasm. Causes of clear cytoplasmic quality in light microscopy are loss of organelles, storage of substances or fixation artefacts. Differential diagnosis of the different clear cell types requires special staining techniques, immunocytochemistry and electron microscopy. A new and distinct salivary gland neoplasm is hyalinizing clear cell carcinoma, which was not included in the second edition of the WHO Classification of Salivary Gland Tumors. Analysis of the collected cases of the Salivary Gland Register Hamburg and recent reports in the literature reveal that this carcinoma shows low-grade malignancy with localization usually in the minor salivary glands. Most cases occur in women. The pathohistology is characterized by solid or trabecular formations of polygonal clear cells which are surrounded by a broad hyalinized desmoplastic connective tissue stroma. The clear cells are mucin negative and express cytokeratin and EMA, in some cases also CEA, but not S-100 protein, actin or other markers of myoepithelial cells. Ultrastructural findings are undifferentiated duct cells with only few organelles and inclusion of glycogen granules. The differential diagnosis includes other clear cell tumours, especially epithelial-myoepithelial carcinoma and the clear cell variants of myoepithelial carcinoma and acinic cell or mucoepidermoid carcinoma.

Adenocarcinoma, Clear Cell↗

Optimization of reading conditions for flat panel displays.

Task Group 18 (TG 18) of the American Association of Physicists in Medicine has developed guidelines for Assessment of Display Performance for Medical Imaging Systems. In this document, a method for determination of the maximum room lighting for displays is suggested. It is based on luminance measurements of a black target displayed on each display device at different room illuminance levels. Linear extrapolation of the above luminance measurements vs. room illuminance allows one to determine diffuse and specular reflection coefficients. TG 18 guidelines have established recommended maximum room lighting. It is based on the characterization of the display by its minimum and maximum luminance and the description of room by diffuse and specular coefficients. We carried out these luminance measurements for three selected displays to determine their optimum viewing conditions: one cathode ray tube and two flat panels. We found some problems with the application of the TG 18 guidelines to optimize viewing conditions for IBM T221 flat panels. Introduction of the requirement for minimum room illuminance allows a more accurate determination of the optimal viewing conditions (maximum and minimum room illuminance) for IBM flat panels. It also addresses the possible loss of contrast in medical images on flat panel displays because of the effect of nonlinearity in the dependence of luminance on room illuminance at low room lighting.

Computer Terminals↗

Building a projection map for photoreceptor neurons in the Drosophila optic lobes.

The sensory tasks performed by the eye are diverse and complex. In Drosophila, the eye performs motion detection for navigation as well as detection of the quality of light (color and polarized light). Both types of inputs are processed separately, as different photoreceptors are specialized in these tasks and contact different target cell layers in the optic lobe. However, their respective outputs are likely to be integrated in higher brain centers. Here, we discuss the cell diversity and potential role of the several ganglia that form the fly optic lobe. We also discuss the power of modern genetic tools to provide the potential to trace the visual neural networks.

Animals↗

Expedient liquid chromatographic method with fluorescence detection for montelukast sodium in micro-samples of plasma.

This study describes an expedient assay for the analysis of the asthma medication, montelukast sodium (Singulair, MK-0476), in human plasma samples. After a simple extraction of the plasma, the drug and internal standard, quinine bisulfate, were measured by HPLC. The chromatographic system consisted of a single pump, a refrigerated autosampler, a C8 4-microm particle size radial compression cartridge at 40 degrees C and a fluorescence detector with the excitation and emission wavelengths set at 350 and 400 nm, respectively. The mobile phase which was delivered at 1.0 ml/min, was prepared by adding 200 ml of 0.025 M sodium acetate, pH adjusted to 4.0 with acetic acid, to 800 ml of acetonitrile, with 50 microl triethylamine. With a run time of only 10 min per sample, this assay had an overall recovery of >97% with a detection limit of 1 ng/ml. The inter- and intra-run relative standard deviations at 0.05, 0.2 and 1.0 microg/ml were all <9.2%, while the analytical recovery at the same concentrations were within 7.7% of the amount added.

Acetates↗

Visualization of individual single-walled carbon nanotubes by fluorescent polymer wrapping.

Manipulating optical properties of single-walled nanotubes (SWNTs) is necessary for the development of nanoscale optical devices and probes for biomedical research. In life sciences it will make possible the direct observation of SWNTs inside living cells using optical microscopes. In the nanotechnology field it will enable the development of nanosensors with fluorescent reporting. However, the direct fluorescent labeling of SWNTs is obstructed by their strong light quenching qualities. Besides, chemical functionalization of SWNTs needed for the covalent attachment of fluorescent dyes could change favorable properties of nanotubes. Here we report that optical properties of SWNTs can be manipulated without their covalent modification by wrapping them with fluorescently labeled polymer poly(vinylpyrrolidone) (PVP-1300). Fluorescent PVP-1300 forms a monomolecular approximately 2.5 nm thick layer coiling around individual SWNTs and nanotube bundles. PVP casing is fluorescent although it is only several nanometers thick. This makes individual SWNTs observable by a fluorescent microscope. The spare polymer strands left over after wrapping around the relatively shorter nanotubes form junctions between SWNTs tying them together into new configurations, primarily Y- and psi-type junctions. The ability to use a single fluorescent polymer strand to fasten nanotubes together can be useful in assembly of nanotube-made devices. In PVP-covered SWNTs multiple fluorophores are attached to each single nanotube making them unique composite fluorophores attractive as parts of biological fluorescent probes and in the development of the new materials in photonics and nanotechnology.

Image Enhancement↗