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

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

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

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

2

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

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

A series of disulfide-linked dendritic phthalocyanines were synthesized. Having 2 to 6 zinc(II) phthalocyanine units in a molecule, these compounds were significantly self-quenched, particularly in the citrate solution. Both the fluorescence intensity and singlet oxygen generation efficiency were significantly lower than those of the monomeric counterpart, and the self-quenching efficiency increased as the number of phthalocyanine unit increased. Upon interaction with 5 mM of glutathione (GSH) in the citrate solution, the fluorescence intensity of these compounds was increased as a result of the cleavage of the disulfide linkages and separation of the phthalocyanine units, thereby reducing the self-quenching effect. GSH could also enhance the fluorescence emission inside human colon adenocarcinoma HT29 cells and promote the formation of singlet oxygen of these compounds. Upon irradiation, their IC50 values were found to be in the range of 0.18-0.38 M. Finally, the biodistribution and activation of PC2 and PC6 were also examined in HT29 tumor-bearing nude mice. For both compounds, the fluorescence intensity per unit area at the tumor was found to grow gradually during the first 24 h. While the intensity was then dropped for PC2, the intensity for PC6 remained steady over the following 6 days, which might be a result of the enhanced permeability and retention effect arising from the larger molecular mass of the hexameric system.

Concepts: Fluorescence, Oxygen, Molecule, Polymer chemistry, Singlet oxygen, Photodynamic therapy, Triplet oxygen, Conversion of units

0

The physical model test of landslides is important for studying landslide structural damage, and parameter measurement is key in this process. To meet the measurement requirements for deep displacement in landslide physical models, an automatic flexible inclinometer probe with good coupling and large deformation capacity was designed. The flexible inclinometer probe consists of several gravity acceleration sensing units that are protected and positioned by silicon encapsulation, all the units are connected to a 485-comunication bus. By sensing the two-axis tilt angle, the direction and magnitude of the displacement for a measurement unit can be calculated, then the overall displacement is accumulated according to all units, integrated from bottom to top in turn. In the conversion from angle to displacement, two spline interpolation methods are introduced to correct and resample the data; one is to interpolate the displacement after conversion, and the other is to interpolate the angle before conversion; compared with the result read from checkered paper, the latter is proved to have a better effect, with an additional condition that the displacement curve move up half the length of the unit. The flexible inclinometer is verified with respect to its principle and arrangement by a laboratory physical model test, and the test results are highly consistent with the actual deformation of the landslide model.

Concepts: Measurement, Metrology, Linear interpolation, Test method, Units of measurement, Interpolation, Conversion of units, Spline

0

Poly-N-acetyllactosamine (poly-LacNAc) structures on glycoproteins play important roles in essential biological events such as cell-cell adhesion. Here, we report a new strategy for the semisynthesis of LacNAc-extended complex-type biantennary oligosaccharides. We found an efficient isopropylidenation reaction that selectively protects the terminal Gal-3,4-OH of a biantennary complex-type nonasaccharide isolated from a natural source. This finding enabled the conversion of the nonasaccharide into the two types of oligosaccharides containing di-LacNAc units at one or two antennae via ten-step chemical sequences.

Concepts: The Terminal, Carbohydrate chemistry, The Conversion, Oligosaccharides, Conversion of units, Oligosaccharide