SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Conversion of units

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In patients with cutaneous melanoma, mitotic rate (MR) historically has been reported as the number of mitoses per high-power field (hpf) or per 10 hpf. The most recent revision of the American Joint Committee on Cancer melanoma staging system now incorporates MR and specifies that MR should be reported as mitoses per mm(2), with a conversion factor of 1 mm(2) equaling 4 hpf. However, because many pathologists continue to report MR in hpf units, we sought to compare the 2 conventions for reporting MR; this is important now that MR is used for staging and prognostic information.

Concepts: Cancer, Lung cancer, Cell cycle, Report, Melanoma, Mitosis, The Colbert Report, Conversion of units

28

Abstract Objectives. Because of its good matching performance the VITA 3D-Master shade guide (3D) is frequently used for determination of tooth color. Numerous composites/ceramics are, however, available in VITA Classical (VC) shades only. The objective of this study was to investigate the possibility of performing a shade match with 3D Master and converting this result via a table in a VC shade (indirect method) without this resulting in an apparent inferior shade matching in comparison with direct shade matching with the VC. Methods. Experiments were performed with an artificial, computer-generated tooth color space. Conversion tables were generated by calculating the color difference (ΔE) between a 3D shade and the closest VC shade (simple conversion table) and with the aid of optimization procedures. Statistical differences between the direct and indirect methods and between the indirect methods were assessed by use of a U-test. Results. Median ΔE was 2.38 for direct matching with the VC and 2.86 for indirect matching by use of a simple conversion table (p < 0.01). Optimized tables performed slightly better (median ΔE = 2.81). Conclusions. Within the limitations of the study, it is usually possible to determine tooth color with the 3D and convert it, via a table, into a VC shade without adding a clinically apparent error to the direct shade match with the VC.

Concepts: Color space, Conversion of units, Ton

27

Two new D-π-A sensitizers ( and ) incorporating 5H-[1,2,5]thiadiazolo [3,4-f]isoindole-5,7(6H)-dione and 6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione core structures were synthesized and tested in liquid dye-sensitized solar cells (DSCs). achieved a promising power conversion efficiency (PCE) of 6.2% (AM 1.5, 100 mW cm(-2)).

Concepts: Solar cell, Titanium dioxide, Energy conversion, Energy conversion efficiency, Dye-sensitized solar cell, Thin film solar cell, IBM, Conversion of units

26

While several thousand square kilometers of land area have been subject to surface mining in the Central Appalachians, no reliable estimate exists for how much coal is produced per unit landscape disturbance. We provide this estimate using regional satellite-derived mine delineations and historical county-level coal production data for the period 1985-2005, and further relate the aerial extent of mining disturbance to stream impairment and loss of ecosystem carbon sequestration potential. To meet current US coal demands, an area the size of Washington DC would need to be mined every 81 days. A one-year supply of coal would result in ∼2,300 km of stream impairment and a loss of ecosystem carbon sequestration capacity comparable to the global warming potential of >33,000 US homes. For the first time, the environmental impacts of surface coal mining can be directly scaled with coal production rates.

Concepts: Carbon dioxide, Kilometre, Methane, Coal, Global warming, Coal mining, Anthracite, Conversion of units

11

Relative-value units (RVUs) were developed in 1988 as a method of accounting for physicians' work effort and hospital or clinic expenses. Because RVUs provided a uniform, formulaic metric for myriad clinical services, they quickly became the prevailing method for setting fee-for-service payments for Medicare and private insurance. However, the dominance of the fee-for-service model has created strong structural impediments to physicians' participation in value-focused health care.(1) The success of new models of care will require not only changes in the way that health systems are organized and paid but also vigorous engagement by generalists and specialists, yet RVU formulas for . . .

Concepts: Health care, Health economics, Medicine, Health insurance, Hospital, System, Clinic, Conversion of units

4

Medication overdoses are a common, but preventable, problem among children. Volumetric dosing errors and the use of incorrect dosing delivery devices are 2 common sources of these preventable errors for orally administered liquid medications. To reduce errors and increase precision of drug administration, milliliter-based dosing should be used exclusively when prescribing and administering liquid medications. Teaspoon- and tablespoon-based dosing should not be used. Devices that allow for precise dose administration (preferably syringes with metric markings) should be used instead of household spoons and should be distributed with the medication.

Concepts: Pharmacology, Drug, Pharmaceutical drug, Units of measurement, Litre, Barbiturate, Injection, Conversion of units

3

The aim of this study was to retrospectively evaluate the patient effective dose (ED) for different PET/CT procedures performed with a variety of PET radiopharmaceutical compounds. PET/CT studies of 210 patients were reviewed including Torso (n = 123), Whole body (WB) (n = 36), Head and Neck Tumor (HNT) (n = 10), and Brain (n = 41) protocols with (18)FDG (n = 170), (11)C-CHOL (n = 10), (18)FDOPA (n = 10), (11)C-MET (n = 10), and (18)F-florbetapir (n = 10). ED was calculated using conversion factors applied to the radiotracer activity and to the CT dose-length product.

Concepts: Medicine, Head and neck anatomy, Head and neck, Patient, Hospital, Patience, Effective dose, Conversion of units

1

Recently, a growing number of Item-Response Theory (IRT) models has been published, which allow estimation of a common latent variable from data derived by different Patient Reported Outcomes (PROs). When using data from different PROs, direct estimation of the latent variable has some advantages over the use of sum score conversion tables. It requires substantial proficiency in the field of psychometrics to fit such models using contemporary IRT software. We developed a web application ( http://www.common-metrics.org ), which allows estimation of latent variable scores more easily using IRT models calibrating different measures on instrument independent scales.

Concepts: Statistics, Mathematics, Estimation theory, Psychometrics, Scores, Estimation, Outcome, Conversion of units

0

Through fusing isoindigo (IID) units at 6,7;6',7'-positions, a series of new near-infrared (NIR) absorbing and stable ribbon-like conjugated molecules, i.e., nIIDs in which n represents the number of IID units, have been synthesized. The optical band gaps (E_g^opt) of the molecules are lowered from 2.03 eV of 1IID to 1.12 eV of 6IID with the increase of the conjugation length. 3IID, 4IID and 6IID have strong absorption in NIR region and exhibit photothermal conversion efficiencies > 50% under laser irradiation at λ = 808 nm.

Concepts: Electromagnetic radiation, Laser, Solar cell, Units of measurement, Band gap, The Band, Conversion of units, Band

0

The paper presents the evaluation of gamma contribution in a neutron calibration field of a241Am-Be source. The characterization of gamma flux spectra and gamma ambient dose equivalent rates has been performed using a portable NaI(Tl) gamma spectrometer. For obtaining the gamma ambient dose equivalent rates from the measured spectra, two approaches were applied based on the applications of the G(E) function and the ICRP 74 conversion factors, respectively. Comparison of the gamma ambient dose equivalent rates obtained from the two approaches shows an agreement within 5%. The gamma contribution in the neutron calibration field is evaluated about 2.3-3.3% of the total neutron ambient dose equivalent rate in the distance range of 100-250cm.

Concepts: Ionizing radiation, Measurement, Rates, Real number, Units of measurement, Reaction rate, Conversion of units, Field Island