The Response of Five Tropical Plant Species to Natural Solar Ultraviolet-B Radiation

Tropical regions currently receive the highest global levels of solar ultraviolet-B radiation (UV-B, 280-320 nm) even without ozone depletion. Thus, the influence of natural, present-day UV-B irradiance in the tropics was examined for five tropical species, including three native rainforest tree species and two economically important species. Solar UV-B radiation conditions were obtained vi using either a UV-B excluding plastic film or a near-ambient UV-B transmitting film in a small clearing on Barro Colorado Island (BCI), Panama (9 ° N). Significant differences were often exhibited as increased foliar UV-B absorbing compounds, increased leaf mass per area, and reduced leaf blade length for plants receiving solar UV-B radiation. Plant height was typically reduced under solar UV-B, but some variation among species in response was seen. Biomass and photosystem II function using chlorophyll fluorescence were generally unaffected. The results of this study provide strong evidence that tropical vegetation, including native rainforest species, responds to the present level of natural solar UV-B. This suggests that even a small increase in UV-B radiation with ozone depletion may have biological implications

Wall mediated transport in confined spaces: Exact theory for low density

We present a theory for the transport of molecules adsorbed in slit and cylindrical nanopores at low density, considering the axial momentum gain of molecules oscillating between diffuse wall reflections. Good agreement with molecular dynamics simulations is obtained over a wide range of pore sizes, including the regime of single-file diffusion where fluid-fluid interactions are shown to have a negligible effect on the collective transport coefficient. We show that dispersive fluid-wall interactions considerably attenuate transport compared to classical hard sphere theory

Does evidence influence policy? Resource allocation and the Indigenous Burden of Disease study

Objective The Indigenous Burden of Disease (IBoD) report is the most comprehensive assessment of Indigenous disease burden in Australia. The aim of the present study was to investigate the potential effect of the IBoD report on Australian Indigenous health policy, service expenditure and research funding. Findings have significance for understanding factors that may influence Indigenous health policy. Methods The potential effect of the IBoD report was considered by: (1) conducting a text search of pertinent documents published by the federal government, Council of Australian Governments and the National Health and Medical Research Council of Australia (NHMRC) and observing the quantity and quality of references to IBoD; (2) examining data on government Indigenous healthcare expenditure for trends consistent with the findings and policy implications of the IBoD report; and (3) examining NHMRC Indigenous grant allocation trends consistent with the findings and policy implications of the IBoD report. Results Of 110 government and NHMRC documents found, IBoD was cited in 27. Immediately after publication of the IBoD report, federal and state governments increased Indigenous health spending (relative to non-Indigenous), notably for community health and public health at the state level. Expenditure on Indigenous hospital separations for chronic diseases also increased. These changes are broadly consistent with the findings of the IBoD report on the significance of chronic disease and the need to address certain risk factors. However, there is no evidence that such changes had a causal connection with the IBoD study. After publication of the IBoD report, changes in NHMRC Indigenous research funding showed little consistency with the findings of the IBoD report. Conclusions The present study found only indirect and inconsistent correlational evidence of the potential influence of the IBoD report on Indigenous health expenditure and research funding. Further assessment of the potential influence of the IBoD report on Indigenous health policy will require more targeted research, including interviews with key informants involved in developing health policy. What is known about the topic? There are currently no publications that consider the potential effed of the IBoD study on Indigenous health expenditure and research funding. What does this paper add? This paper offers the first consideration of the potential effect of the IBoD report. It contains analyses of data from readily available sources, examining national expenditures on Indigenous health and NHMRC Indigenous research, before and after the publication of the IBoD report. What are the implications for practitioners? The paper is relevant to analysts interested in drivers of Indigenous health policy. Although it finds correlations between the release of the IBoD report and some subsequent health spending decisions, other factors should be investigated to better understand the complexity of processes that drive government efforts to improve Indigenous health

Moderated peer assessment of individual contribution to group work

UCL Engineering trains students to use engineering knowledge within extended group practical activities to prepare them for their careers after graduation. However, despite the substantial educational benefits of getting students to work in teams, providing individual assessment can be challenging. Students frequently express dissatisfaction if all members of a team are given the same mark regardless of the individual effort. Here, we aim to promote student engagement and improve student experience during group work by giving each student an individual mark. The individual mark results from multiplying the overall “group mark” by a personal contribution factor. This personal contribution is assessed directly by peers, who are aware of each team member’s contribution, encouraging self-reflection, and moderated by tutors when necessary. This practice has been well received by students in other universities. We are working with a student committee to identify and evaluate various methods and e-learning systems that would aid us to run this practice efficiently even for large numbers of students. This includes rules to flag cases requiring moderation. This project, partially funded by ELDG 2015, fits with our aim of increasing students’ satisfaction and engagement with assessment. We have combined it with our ‘360 degrees peer assessment method’, which we presented at last year’s conference, to provide a reliable and individual peer assessment of group work. We provide a novel approach to group assessment which encourages self-reflection and is intended to improve the learning experience and student satisfaction during group work, in line with UCL 2034

On the Fluctuation Relation for Nose-Hoover Boundary Thermostated Systems

We discuss the transient and steady state fluctuation relation for a mechanical system in contact with two deterministic thermostats at different temperatures. The system is a modified Lorentz gas in which the fixed scatterers exchange energy with the gas of particles, and the thermostats are modelled by two Nos\'e-Hoover thermostats applied at the boundaries of the system. The transient fluctuation relation, which holds only for a precise choice of the initial ensemble, is verified at all times, as expected. Times longer than the mesoscopic scale, needed for local equilibrium to be settled, are required if a different initial ensemble is considered. This shows how the transient fluctuation relation asymptotically leads to the steady state relation when, as explicitly checked in our systems, the condition found in [D.J. Searles, {\em et al.}, J. Stat. Phys. 128, 1337 (2007)], for the validity of the steady state fluctuation relation, is verified. For the steady state fluctuations of the phase space contraction rate \zL and of the dissipation function \zW, a similar relaxation regime at shorter averaging times is found. The quantity \zW satisfies with good accuracy the fluctuation relation for times larger than the mesoscopic time scale; the quantity \zL appears to begin a monotonic convergence after such times. This is consistent with the fact that \zW and \zL differ by a total time derivative, and that the tails of the probability distribution function of \zL are Gaussian.Comment: Major revision. Fig.10 was added. Version to appear in Journal of Statistical Physic

Stationary and Transient Work-Fluctuation Theorems for a Dragged Brownian Particle

Recently Wang et al. carried out a laboratory experiment, where a Brownian particle was dragged through a fluid by a harmonic force with constant velocity of its center. This experiment confirmed a theoretically predicted work related integrated (I) Transient Fluctuation Theorem (ITFT), which gives an expression for the ratio for the probability to find positive or negative values for the fluctuations of the total work done on the system in a given time in a transient state. The corresponding integrated stationary state fluctuation theorem (ISSFT) was not observed. Using an overdamped Langevin equation and an arbitrary motion for the center of the harmonic force, all quantities of interest for these theorems and the corresponding non-integrated ones (TFT and SSFT, resp.) are theoretically explicitly obtained in this paper. While the (I)TFT is satisfied for all times, the (I)SSFT only holds asymptotically in time. Suggestions for further experiments with arbitrary velocity of the harmonic force and in which also the ISSFT could be observed, are given. In addition, a non-trivial long-time relation between the ITFT and the ISSFT was discovered, which could be observed experimentally, especially in the case of a resonant circular motion of the center of the harmonic force.Comment: 20 pages, 3 figure

Multiplex SNP Discrimination

Multiplex hybridization reactions of perfectly matched duplexes and duplexes containing a single basepair mismatch (SNPs) were investigated on DNA microarrays. Effects of duplex length, G-C percentage, and relative position of the SNP on duplex hybridization and SNP resolution were determined. Our theoretical model of multiplex hybridization accurately predicts observed results and implicates target concentration as a critical variable in multiplex SNP detection

Addition compounds of n-methyl cyclic imines with trimethylboron,

A manometric investigation was made of the addition compounds of trimethylboron with the N-methyl derivatives of ethylenimine (aziridine), trimethylenimine (azetidine), pyrrolidine and piperidine. The stability order obtained was 3->4->5->6-membered ring. This order is different from that reported by and (1) for the trimethylboron addition compounds with the unsubstituted cyclic imines, the order being 4->5->6->3-membered ring. The complete reversal in position of the 3-membered ring upon substituting a methyl group for the hydrogen on the nitrogen in this series is due to large steric interaction. This effect becomes more pronounced as the ring size increases, thereby leading to the systematic decrease in stability. Only in the case of the 3-membered ring does methyl substitution result in a more stable addition compound. For the other ring compounds methyl substitution results in decreased stability, the decrease becoming progressively larger as the ring size increases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32378/1/0000453.pd

Fluctuation formula for nonreversible dynamics in the thermostated Lorentz gas

We investigate numerically the validity of the Gallavotti-Cohen fluctuation formula in the two and three dimensional periodic Lorentz gas subjected to constant electric and magnetic fields and thermostated by the Gaussian isokinetic thermostat. The magnetic field breaks the time reversal symmetry, and by choosing its orientation with respect to the lattice one can have either a generalized reversing symmetry or no reversibility at all. Our results indicate that the scaling property described by the fluctuation formula may be approximately valid for large fluctuations even in the absence of reversibility.Comment: 6 pages, 6 figure

Comparison of work fluctuation relations

We compare two predictions regarding the microscopic fluctuations of a system that is driven away from equilibrium: one due to Crooks [J. Stat. Phys. 90, 1481 (1998)] which has gained recent attention in the context of nonequilibrium work and fluctuation theorems, and an earlier, analogous result obtained by Bochkov and Kuzovlev [Zh. Eksp. Teor. Fiz. 72(1), 238247 (1977)]. Both results quantify irreversible behavior by comparing probabilities of observing particular microscopic trajectories during thermodynamic processes related by time-reversal, and both are expressed in terms of the work performed when driving the system away from equilibrium. By deriving these two predictions within a single, Hamiltonian framework, we clarify the precise relationship between them, and discuss how the different definitions of work used by the two sets of authors gives rise to different physical interpretations. We then obtain a extended fluctuation relation that contains both the Crooks and the Bochkov-Kuzovlev results as special cases.Comment: 14 pages with 1 figure, accepted for publication in the Journal of Statistical Mechanic