SciCombinator

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

Concept: Calculus

411

 To investigate whether language used in science abstracts can skew towards the use of strikingly positive and negative words over time.

Concepts: Scientific method, Mathematics, Physics, Science, Engineering, Calculus, Empirical, Axiom

150

An essential element in the web-trap architecture, the capture silk spun by ecribellate orb spiders consists of glue droplets sitting astride a silk filament. Mechanically this thread presents a mixed solid-liquid behavior unknown to date. Under extension, capture silk behaves as a particularly stretchy solid, owing to its molecular nanosprings, but it totally switches behavior in compression to now become liquid-like: It shrinks with no apparent limit while exerting a constant tension. Here, we unravel the physics underpinning the unique behavior of this “liquid wire” and demonstrate that its mechanical response originates in the shape-switching of the silk filament induced by buckling within the droplets. Learning from this natural example of geometry and mechanics, we manufactured programmable liquid wires that present previously unidentified pathways for the design of new hybrid solid-liquid materials.

Concepts: Calculus, Liquid, Surface tension, Arachnid, Spider silk, Spider, Wire, Mechanical

150

Methods for the integrative analysis of multi-omics data are required to draw a more complete and accurate picture of the dynamics of molecular systems. The complexity of biological systems, the technological limits, the large number of biological variables and the relatively low number of biological samples make the analysis of multi-omics datasets a non-trivial problem.

Concepts: Molecular biology, Mathematics, Calculus, Set theory, Logic, Computational complexity theory, Systems biology, Number names

140

 To quantify how a period of intense media coverage of controversy over the risk:benefit balance of statins affected their use.

Concepts: Statistics, Series, Statin, Calculus, Time series, Seasonality

90

The substantial gender gap in the science, technology, engineering, and mathematics (STEM) workforce can be traced back to the underrepresentation of women at various milestones in the career pathway. Calculus is a necessary step in this pathway and has been shown to often dissuade people from pursuing STEM fields. We examine the characteristics of students who begin college interested in STEM and either persist or switch out of the calculus sequence after taking Calculus I, and hence either continue to pursue a STEM major or are dissuaded from STEM disciplines. The data come from a unique, national survey focused on mainstream college calculus. Our analyses show that, while controlling for academic preparedness, career intentions, and instruction, the odds of a woman being dissuaded from continuing in calculus is 1.5 times greater than that for a man. Furthermore, women report they do not understand the course material well enough to continue significantly more often than men. When comparing women and men with above-average mathematical abilities and preparedness, we find women start and end the term with significantly lower mathematical confidence than men. This suggests a lack of mathematical confidence, rather than a lack of mathematically ability, may be responsible for the high departure rate of women. While it would be ideal to increase interest and participation of women in STEM at all stages of their careers, our findings indicate that if women persisted in STEM at the same rate as men starting in Calculus I, the number of women entering the STEM workforce would increase by 75%.

Concepts: Mathematics, Physics, Gender, Science, Geometry, Calculus, Gender role, Woman

58

New data from the NIH reveal that the scientific return on its sponsored research reaches a maximum at around $400,000 of annual support per principal investigator. We discuss the implications of this ‘sweet spot’ for funding policy, and propose that the NIH should limit both the minimum and maximum amount of funding per researcher.

Concepts: Calculus, Maxima and minima, Finance

33

Unexpectedly large ocean waves or ‘rogues’ are sometimes claimed to be the cause of damage to ships at sea and to offshore structures. While wind-driven wave models are capable of predicting the average characteristics of waves, the maximum height of rogues that may occur is yet unknown. Rogues form in the open ocean through the addition of elemental wave trains or groups and, infrequently, with many elements coming together in phase, producing rogues. Here we perform directional analyses on one of the steepest rogues ever recorded: the Andrea wave. We find that the Andrea wave was close to the breaking-limited height. Analysis of the 72 twenty minute records on the day of the Andrea wave yields encounter return periods of about 21 days for maximally steep waves, while less steep rogues occur about twice daily. An explicit formula is given for the encounter probability, based on the target area. This work answers the critical questions regarding rogues in the design and operation of ships and offshore structures: how high can rogues be and how frequently they occur.

Concepts: Critical thinking, Quantum mechanics, Calculus, Wave, Phase, Sea, Ocean, Ocean waves

33

In 2007, the province of British Columbia implemented incentive payments to primary care physicians for the provision of comprehensive, continuous, guideline-informed care for patients with 2 or more chronic conditions. We examined the impact of this program on primary care access and continuity, rates of hospital admission and costs.

Concepts: Medicine, Hospital, Physician, Calculus, Derivative, Provinces and territories of Canada, Canada, British Columbia

28

A highly sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for the determination of limonin in beagle dog plasma using nimodipine as internal standard. The analyte and internal standard (IS) were extracted with ether followed by a rapid isocratic elution with 10 mm ammonium acetate buffer-methanol (26:74, v/v) on a C column (150 × 2.1 mm i.d.) and subsequent analysis by mass spectrometry in the multiple reaction monitoring mode. The precursor to product ion transitions of m/z 469.4 → 229.3 and m/z 417.2 → 122.0 were used to measure the analyte and the IS. The assay was linear over the concentration range of 0.625-100 ng/mL for limonin in dog plasma. The lower limit of quantification was 0.312 ng/mL and the extraction recovery was >90.4% for limonin. The inter- and intra-day precision of the method at three concentrations was less than 9.9%. The method was successfully applied to pharmacokinetic study of limonin in dogs. Copyright © 2012 John Wiley & Sons, Ltd.

Concepts: Ammonia, Mass spectrometry, Calculus, Analytical chemistry, Liquid chromatography-mass spectrometry, Titration

28

A multicentred study derived from the COLIPA in vitro UVA method was performed to assess the influence of test conditions on UVA protection factor (UVAPF) values in terms of amplitude, reproducibility between laboratories and correlation with in vivo UVA results. Eight products with a range of in vivo UVAPF from three to 29 were used. Two different types of plates, namely high-roughness (5 μm) and low-roughness (2 μm) plates, were used with a different application rate for each (1.3 mg cm(-2) and 0.75 mg cm(-2) respectively). The UVR dose applied to both plate types followed the same principle as the original test (1.2 J. cm(-2)  × UVAPF0). Strong, significant correlations between in vitro and in vivo UVAPF values were observed for both plate types (Pearson correlation > 0.9, P ≤ 0.01). The correlation and slope obtained with the low-roughness plates confirmed the previous results obtained by COLIPA. Across all laboratories, higher UVAPF values were obtained on the high-roughness plates (P < 0.01). Reproducibility of UVAPF values between laboratories was comparable between the two plate roughness values (low roughness, COV = 8%; high roughness, COV = 12%). Considering the in vitro/in vivo comparisons, a regression slope of 0.83 was observed for the low-roughness plates, in comparison with a value of 1.05 for the high-roughness plates. The accuracy of the method was improved, therefore, with the use of the high-roughness plates. With a constraint to recommend the use of only one plate type in the COLIPA UVA in vitro Test, the high-roughness plate was selected on an on-going basis to limit variability of results and to provide better accuracy with in vivo data.

Concepts: Scientific method, In vivo, Psychometrics, Calculus, In vitro, Correlation and dependence, Pearson product-moment correlation coefficient