Does Long-Term Macrophyte Management in Lakes Affect Biotic Richness and Diversity?

We hypothesize that the richness and diversity of the biota in Lake Moraine (42°50’47”N, 75°31’39”W) in New York have been negatively impacted by 60 years of macrophyte and algae management to control Eurasian watermilfoil ( Myriophyllum spicatum L.) and associated noxious plants. To test this hypothesis we compare water quality characteristics, richness and selected indicators of plant diversity, zooplankton, benthic macroinvertebrates and fish in Lake Moraine with those in nearby Hatch Lake (42°50’06”N, 75°40’67”W). The latter is of similar size and would be expected to have similar biota, but has not been subjected to management. Measurements of temperature, pH, oxygen, conductivity, Secchi transparency, calcium, total phosphorus and nitrites + nitrates are comparable. Taxa richness and the diversity indices applied to the aquatic macrophytes are similar in both lakes. (PDF has 8 pages.

Analysis of standing vertical jumps using a force platform

A force platform analysis of vertical jumping provides an engaging demonstration of the kinematics and dynamics of one-dimensional motion. The height of the jump may be calculated (1) from the flight time of the jump, (2) by applying the impulse–momentum theorem to the force–time curve, and (3) by applying the work–energy theorem to the force-displacement curve

Effect of interface fields on the piezoelectric response of aluminum nitride thin films

Group III-Nitride wide bandgap semiconductors have attracted much attention in the optoelectronic and electronic research areas recently. III-Nitride semiconductor materials are attractive materials for use in optoelectronic and high speed electronics devices because they are direct bandgap semiconductors and the bandgap can be varied over a wide range. It has also been shown that the III-Nitride group of materials function exceptionally well in harsh environments. The piezoelectric properties of the III-Nitride material system have been studied and several of the III-Nitride compounds have been found to have non zero piezoelectric coefficients. This work shows that the observed piezoelectric coefficient of Aluminum Nitride (AlN) is directly related to the metal used as the topside contact. The data and preliminary analysis presented here indicate that AlN cannot be treated as an insulating material and must be treated as a semiconductor in order to model its piezoelectric behavior

FORTEST: Formal methods and testing

Formal methods have traditionally been used for specification and development of software. However there are potential benefits for the testing stage as well. The panel session associated with this paper explores the usefulness or otherwise of formal methods in various contexts for improving software testing. A number of different possibilities for the use of formal methods are explored and questions raised. The contributors are all members of the UK FORTEST Network on formal methods and testing. Although the authors generally believe that formal methods are useful in aiding the testing process, this paper is intended to provoke discussion. Dissenters are encouraged to put their views to the panel or individually to the authors

Nuclear-resonant electron scattering

We investigate nuclear-resonant electron scattering as occurring in the two-step process of nuclear excitation by electron capture (NEEC) followed by internal conversion. The nuclear excitation and decay are treated by a phenomenological collective model in which nuclear states and transition probabilities are described by experimental parameters. We present capture rates and resonant strengths for a number of heavy ion collision systems considering various scenarios for the resonant electron scattering process. The results show that for certain cases resonant electron scattering can have significantly larger resonance strengths than NEEC followed by the radiative decay of the nucleus. We discuss the impact of our findings on the possible experimental observation of NEEC.Comment: 24 pages, 2 plots, 5 table

What makes Darwinian hydrology "Darwinian"? Asking a different kind of question about landscapes

There have been repeated calls for a Darwinian approach to hydrologic science, or for a synthesis of Darwinian and Newtonian approaches, to deepen understanding of the hydrologic system in the larger landscape context, and so develop a better basis for predictions now and in an uncertain future. But what exactly makes a Darwinian approach to hydrology "Darwinian"? While there have now been a number of discussions of Darwinian approaches, many referencing Harte (2002), the term is potentially a source of confusion because its connections to Darwin remain allusive rather than explicit. <br><br> Here we suggest that the Darwinian approach to hydrology follows the example of Charles Darwin by focusing attention on the patterns of variation in populations and seeking hypotheses that explain these patterns in terms of the mechanisms and conditions that determine their historical development. These hypotheses do not simply catalog patterns or predict them statistically – they connect the present structure with processes operating in the past. Nor are they explanations presented without independent evidence or critical analysis – Darwin's hypotheses about the mechanisms underlying present-day variation could be independently tested and validated. With a Darwinian framework in mind, it is easy to see that a great deal of hydrologic research has already been done that contributes to a Darwinian hydrology – whether deliberately or not. <br><br> We discuss some practical and philosophical issues with this approach to hydrologic science: how are explanatory hypotheses generated? What constitutes a good hypothesis? How are hypotheses tested? "Historical" sciences – including paleohydrology – have long grappled with these questions, as must a Darwinian hydrologic science. We can draw on Darwin's own example for some answers, though there are ongoing debates about the philosophical nature of his methods and reasoning. Darwin used a range of methods of historical reasoning to develop explanatory hypotheses: extrapolating mechanisms, space for time substitution, and looking for signatures of history. Some of these are already in use, while others are not and could be used to develop new insights. He sought explanatory hypotheses that intelligibly unified disparate facts, were testable against evidence, and had fertile implications for further research. He provided evidence to support his hypotheses by deducing corollary conditions ("if explanation A is true, then B will also be true") and comparing these to observations. <br><br> While a synthesis of the Darwinian and Newtonian approaches remains a goal, the Darwinian approach to hydrologic science has significant value of its own. The Darwinian hydrology that has been conducted already has not been coordinated or linked into a general body of theory and knowledge, but the time is coming when this will be possible

The Duffin-Schaeffer Conjecture with extra divergence II

This paper takes a new step in the direction of proving the Duffin-Schaeffer Conjecture for measures arbitrarily close to Lebesgue. The main result is that under a mild `extra divergence' hypothesis, the conjecture is true.Comment: 7 page

Studies on HDL associated enzymes under experimental hypercholesterolemia: possible modulation on selenium supplementation

<p>Abstract</p> <p>Background</p> <p>Atherosclerosis is a chronic disorder of the arterial wall that starts by formation of fatty streaks and gradually evolves into atherosclerotic plaques. High-density lipoproteins (HDL) blood levels are inversely correlated with atherosclerosis. This beneficial effect of HDL has been partly attributed to its antioxidant properties mediated by paraoxonase1 (PON1) or platelet-activating factor acetylhydrolase (PAF-AH). The present study was aimed to study HDL associated enzymes i.e. PON1 and PAF-AH under experimental hypercholesterolemia and their possible modulation on selenium (Se; an antioxidant) supplementation. Male Sprague Dawley rats were divided into three groups and fed on the control diet, high fat diet (HFD) and HFD + Se respectively for the period of 4 months.</p> <p>Results</p> <p>Cholesterol, triglycerides, HDL and LDL levels were significantly increased by HFD feeding. Selenium supplementation lowered the triglyceride level, whereas the other lipid values remained unchanged. Serum selenium levels were reduced by 31% and ROS levels in the liver were 2-fold increased by HFD. Se supplementation, however, diminished the HFD-induced ROS levels by 29%. Furthermore, Se also improved the HFD-mediated reduction of serum PON1 enzyme activity by 34% and PON1 protein levels by 21%. However, no significant effect of Se was detected on the reduced PAF-AH proteins levels in HFD fed rats. mRNA expression of PON1 and PAF-AH in the liver was not affected in the Se treated groups.</p> <p>Conclusion</p> <p>Se supplementation appears to be protective in hypercholesterolemia by restoring the antioxidant properties of the HDL associated enzyme i.e. PON1 whereas biological system aims towards maintaining the same PAF-AH levels even on selenium supplementation indicating its probable role in both anti and pro-atherogenic activities. Therefore, Se supplementation might be a valuable approach to limit the adverse effects of hypercholesterolemia and may need further investigations.</p

Sensitivity of Ag/Al Interface Specific Resistances to Interfacial Intermixing

We have measured an Ag/Al interface specific resistance, 2AR(Ag/Al)(111) = 1.4 fOhm-m^2, that is twice that predicted for a perfect interface, 50% larger than for a 2 ML 50%-50% alloy, and even larger than our newly predicted 1.3 fOhmm^2 for a 4 ML 50%-50% alloy. Such a large value of 2ARAg/Al(111) confirms a predicted sensitivity to interfacial disorder and suggests an interface greater than or equal to 4 ML thick. From our calculations, a predicted anisotropy ratio, 2AR(Ag/Al)(001)/2AR(Ag/Al)(111), of more then 4 for a perfect interface, should be reduced to less than 2 for a 4 ML interface, making it harder to detect any such anisotropy.Comment: 3 pages, 2 figures, 1 table. In Press: Journal of Applied Physic