bluuebunny/crossref_metadata_2025 huggingface dataset:
A new modelling approach to insect reproduction with same-shape reproduction distribution and rate summation: with particular reference to Russian wheat aphid
Authors: Ma Z.S. , Bechinski E.J.
Published: January 2009

Same-shape distribution model and rate summation approach are widely used to describe the insect developmental process. In this approach, by integrating a nonlinear deterministic developmental rate model and a probabilistic same-shape distribution model, the proportion of the cohort completing development is quantified as a function of accumulating developmental rates, which themselves are temperature dependent. This method is considered to be more accurate in modelling insect phenology because it can address a well-known biological fact, individual variability, that insect individual developmental rates respond to temperature differently, and because rate-summation essentially simulates developmental rates under variable temperatures instead of constant temperatures. By comparing insect development and reproduction with respect to their responses to temperatures, we argue for the extension of the same-shape and rate-summation approaches to modelling insect reproduction process under variable temperatures. We justify our arguments by the fact that individual variation universally exists in almost all biological characteristics, and the phenomenon that insect development and reproduction respond to temperature very similarly, which is supported by some endocrinological evidences reported in literature. In addition, the approach for testing the applicability of the original same-shape developmental modelling, experimentally verifying the sameness of the same-shape curves or that the shape of the curves is invariant with respect to the temperature regimes, equally applies to our extended version for reproduction modelling. We successfully tested the extension and its applicability with our experimental data of 1800 Russian wheat aphids' (RWA) (Diuraphis noxia (Mordvilko)) reproduction under various temperature and plant growth stage regimes. We also extended Taylor's (1981) nonlinear model for insect development to describe RWA mean (median) nymphal production under different temperatures and barley plant growth stages. Three same-shape distribution models, Weibull distribution, Stinner's model and logistic model, are used to construct the same-shape reproduction distribution models for RWA. The extensions performed in this paper contribute a new modelling approach for predicting insect reproduction under field variable temperatures and plant growth stages. The prediction model can be parameterized with data from typical laboratory demography experiments and further integrated into simulation models for insect population dynamics. Finally, we discussed why the sameness test of the same-shape distribution curves is sufficient in validating the approach and proposed a strategy for dealing with exceptional cases where the sameness test fails.
The effect of wattle tannin drenches on gastrointestinal nematodes of tropical sheep and goats during experimental and natural infections
Authors: MAX R. A. , KASSUKU A. A. , KIMAMBO A. E. , MTENGA L. A. , WAKELIN D. , BUTTERY P. J.
Published: January 2009

In previous work, administration of a commercial tannin preparation, quebracho, as oral drench was shown to reduce significantly faecal egg counts (FEC) and worm burdens of temperate sheep with experimental Haemonchus contortus infection. In the current work carried out in Morogoro, Tanzania, three separate animal trials were carried out to investigate the effect of drenches of wattle tannin (WT), a similar tannin preparation that is readily available in the tropics, on nematodes of tropical goats and sheep. In the first trial, 36 young Small East African (SEA) goats were experimentally infected with a single dose of mixed nematode larvae and FEC were monitored regularly. On day 30 post-infection (p.i.), the animals were blocked on the basis of their FEC and randomly assigned into three equal groups (n=12). For 3 consecutive days, two groups received low and high doses of drench at a rate of 1·2 and 2·4 g WT/kg bodyweight, respectively, whereas the third group received a placebo drench (i.e. water). All goats were humanely slaughtered on day 42 p.i. and their worm burdens were assessed. Neither FEC nor worm burdens were significantly reduced by the administration of the low or high dose of WT. The second trial had an identical design but two groups (n=14) of growing Black Head Persian (BHP) sheep were used instead. One group received the drench at 1·5 g WT/kg body wt for 3 consecutive days, whereas the other group received a placebo. Unlike in goats, worm burdens and FEC were significantly reduced (P<0·001) by the drench administration. In the third trial, the effect of WT drench against a naturally acquired nematode infestation in a flock of 34 BHP sheep was determined. FEC were examined three times in a 2-week period and the egg counts were used to block the sheep before being randomly assigned into two groups (n=17). The treated group received the drench at 1·0 g WT/kg bodyweight for 3 consecutive days, while the remaining half was given a placebo. The two groups continued to graze together as FEC were being monitored. Results indicated a significant (P<0·001) reduction in egg counts, which remained low for at least 3 weeks after the drench. The current study demonstrated that the WT drench had significant anthelmintic activity against important nematodes in sheep but not in goats, suggesting an existence of species differences between the two hosts. It was concluded that WT drenches could be used in combination with other worm control strategies to reduce or control nematode infections, at least in sheep.
Melioidosis and tuberculosis: dual pathogens in a neck abscess
Authors: Shenoy V , Kamath M P , Hegde M C , D'Souza T , Mammen S S
Published: January 2009

Introduction:

Melioidosis is an infectious disease caused by a saprophytic bacterium, Burkholderia pseudomallei. It is endemic to Southeast Asia and Northern Australia. It may manifest as a pulmonary lesion, osteomyelitis, abscesses in soft tissue and various organs, or as septicaemia.

Case report:

We report a case of a 40-year-old, diabetic man who presented with a neck lump resulting from super-infection of a tuberculosis cavity with B pseudomallei. The patient was successfully managed by drainage along with meticulous excision of the capsule and prolonged antibiotic and anti-tubercular treatment.

Discussion:

Melioidosis may be confused diagnostically with tuberculosis, as both diseases are endemic in the same regions. Our patient was unfortunate to suffer from both endemic diseases simultaneously, perhaps representing the first such case in the world literature.

Conclusion:

Increased awareness of melioidosis is important as, although the organism is easy to culture, it may be dismissed as a contaminant.
Reterritorialization of a Balinese Chinese Community in Quanzhou, Fujian
Authors: CHEE-BENG TAN
Published: January 2009

This paper is about a special category of guiqiao or ‘returned overseas Chinese’, in southern Fujian. Arriving in China from Bali, Indonesia in 1961, the people were settled in an overseas Chinese farm. The paper illustrates how the re-migrants coped with life in China and how they see themselves today. The returned overseas Chinese reterritorize their Indonesian and Balinese cultural life in China, and they, including the local-born children, speak Balinese and eat Indonesian food. Their experiences provide much food for thought on acculturation, migration and identity as well as on the idea of ‘homeland’.
Rodents as shared indicators for zoonotic parasites of carnivores in urban environments
Authors: REPERANT L. A. , HEGGLIN D. , TANNER I. , FISCHER C. , DEPLAZES P.
Published: January 2009

Rodents are shared intermediate or paratenic hosts forEchinococcus multilocularis,Toxocaraspp. andToxoplasma gondii, and may serve as valuable indicators for assessing the occurrence and the level of environmental contamination and infection pressure with free-living stages of these zoonotic parasites. We investigated 658 non-commensal rodents for parasite infections in the canton of Geneva, Switzerland. The prevalence of infection withE. multiloculariswas highest inArvicola terrestriscaptured in the north-western area (16·5%, CI: 10·1%–24·8%), possibly reflecting a higher red fox density due to the low incidence of sarcoptic mange in this part of the canton. The exposure rate toToxocaraspp. was highest in the urban area (13·2%, CI: 7·9%–20·3%), and may account for higher densities of domestic carnivore and red fox definitive hosts within the city. Exposure toT. gondiiwas widespread (5·0%, CI: 3·2–7·4%), indicating a ubiquitous distribution of infected cat definitive hosts. Interestingly, a widespread distribution ofTaenia taeniaeformis, a parasite mainly transmitted by cats, was similarly evidenced inA. terrestris. Distinct spatial patterns for the different zoonotic parasites likely reflected differences in distribution, abundance, and habitat use of the respective definitive hosts. These results highlight the potential value of rodents as shared indicators for these pathogens.
On a Functional Equation
Authors: Chaundy T. W. , McLeod J. B.
Published: January 2009

We have recently discussed in (1) the general solution of a certain functional equation arising in statistical thermodynamics, and we propose in this note to deal with another functional equation arising from the same source(2).

The problem is to obtain the most general function f(x) which, for all positive integral values of m, n, satifies the functional equation

where

where A is an arbitrary constant. It is the object of this note to prove that this is the only continuous solution.
Latent Roots of Tri-Diagonal Matrices
Authors: Arscott F. M.
Published: January 2009

A considerable amount is known about the latent roots of matrices of the form

in the case when each cross-product of non-diagonal elements, aici-1, is positive. One forms the sequence of polynomials fr(λ) = |Lr−λI| for r = 1, 2, … n, and observes that

then it is easy to deduce that (i) the zeros of fn(λ) and fn_1(λ) interlace—that is, between two consecutive zeros of either polynomial lies precisely one zero of the other (ii) at the zeros of fn(λ) the values of fn-x(λ) are alternately positive and negative, (iii) all the zeros of fn(λ)— i.e. all the latent roots of Ln—are real and different.
The Existence of Integrals of Dynamical Systems Linear in the Velocities
Authors: Kilmister C. W.
Published: January 2009

A dynamical system means here a system specified by generalised coordinates qα(α = 1, 2, …, n) and a Lagrangian L which is a quadratic polynomial in the generalised velocities, say

(with a summation convention).
Upper Bounds for Online Ramsey Games in Random Graphs
Authors: MARCINISZYN MARTIN , SPÖHEL RETO , STEGER ANGELIKA
Published: January 2009

Consider the following one-player game. Starting with the empty graph onnvertices, in every step a new edge is drawn uniformly at random and inserted into the current graph. This edge has to be coloured immediately with one ofravailable colours. The player's goal is to avoid creating a monochromatic copy of some fixed graphFfor as long as possible. We prove an upper bound on the typical duration of this game ifFis from a large class of graphs including cliques and cycles of arbitrary size. Together with lower bounds published elsewhere, explicit threshold functions follow.
Online Ramsey Games in Random Graphs
Authors: MARCINISZYN MARTIN , SPÖHEL RETO , STEGER ANGELIKA
Published: January 2009

Consider the following one-player game. Starting with the empty graph onnvertices, in every step a new edge is drawn uniformly at random and inserted into the current graph. This edge has to be coloured immediately with one ofravailable colours. The player's goal is to avoid creating a monochromatic copy of some fixed graphFfor as long as possible. We prove a lower bound ofnβ(F,r)on the typical duration of this game, where β(F,r) is a function that is strictly increasing inrand satisfies limr→∞β(F,r) = 2 − 1/m2(F), wheren2−1/m2(F)is the threshold of the corresponding offline colouring problem.
Glittery clouds in exoplanetary atmospheres?
Authors: Helling Ch. , Rietmeijer F.J.M.
Published: January 2009

Cloud formation modelling has entered astrophysics as a new field of research for planetary and brown dwarf atmospheres. Clouds are a chemically and physically very active component of an atmosphere since they determine the remaining gas phase and change the object's albedo depending on their material composition. The grains can also provide a surface where the molecular constituents for life can be physisorbed for possible pre-biotic evolution. This paper summarizes our model for the kinetic formation of dirty dust grains which make up the atmospheric clouds of extraterrestrial giant gas planets. We include seed formation, surface growth and evaporation, the gravitational settling that influences the dust formation, element depletion that determines the remaining gas phase abundances, and convective overshooting that is needed for a dust model to be applicable to hydrostatic atmosphere simulations. We demonstrate the evolution of the material composition of the cloud itself and the distribution of the grain sizes in the cloud layer, exemplary for a giant gas planet parameter combinations (Teff, log g). In general, substellar clouds are composed of small, dirty grains with a high silicate content at the cloud deck. They grow in size and gradually purify to iron/corundum grains when they move into denser and hotter atmospheric regions. Comparing these results with experimental data from condensation experiments leads to the conclusion that cloud grains that gravitationally settle in the atmosphere of a giant planet can easily change their lattice structure from the disordered amorphous state they are forming in, into the ordered lattice of a crystal.
On horizontal wind gradient variability from the stratosphere to the lower troposphere in the Arctic
Authors: Lukovich J. V. , Barber D. G.
Published: January 2009

Previous studies have demonstrated changes in vertical wind shear in recent decades, with implications for upward‐propagating planetary waves, the stratospheric polar vortex, and tracer transport. Changes in vertical wind shear combined with horizontal gradients have also been shown to contribute to an increase in vertical gradients in tracer fields, with important implications for vertical transport. In order to explore the extent to which changes in vertical wind shear are reflected in changes to horizontal stirring, we examine horizontal wind gradient fields from the stratosphere to the lower troposphere from 1979 to 2006. Studied in particular are the spatial and temporal properties and trends for relative vorticity, divergence, strain, and the Okubo‐Weiss criterion (which monitors the competition between strain‐ and vorticity‐dominated fields) to illustrate how horizontal wind gradients have changed over the last several decades. The results from this investigation show negative vorticity and strain anomalies during winter following 1998 associated with an increase in sudden stratospheric warmings and perturbations to the polar vortex noted in recent years. Spatial distributions for relative vorticity and strain fields exhibit coherent structures near the tropopause and middle stratosphere during fall and winter, which are captured by the Okubo‐Weiss fields. Trend analyses highlight statistically significant trends in relative vorticity and Okubo‐Weiss fields during winter. The results from this investigation demonstrate that statistically significant trends exist from the stratosphere to the lower troposphere. It is hypothesized that the coupling from the lower troposphere to the upper atmosphere will be important in the development of our understanding of the response of sea ice concentrations to climate variability and change.
Sensitivity of bare soil albedo to surface soil moisture on the moraine of the Zongo glacier (Bolivia)
Authors: Gascoin S. , Ducharne A. , Ribstein P. , Perroy E. , Wagnon P.
Published: January 2009

The dependence of bare soil albedo on soil water content is investigated using in situ data collected on the moraine of an Andean glacier (Bolivia). This study demonstrates a high negative correlation between the two variables that is best approximated by an exponential function, in agreement with previous studies. More importantly, the average snow‐free albedo value during the rainy season is 40% lower than during the dry season (0.16 vs. 0.26). These results are relevant for climate and land surface modeling applications, where bare soil albedo is often considered as a constant parameter.
More constraints on internal heating rate of the Earth's mantle from plume observations
Authors: Leng Wei , Zhong Shijie
Published: January 2009

Our previous numerical studies of plume dynamics without secular cooling effects demonstrated that the internal heating rate of the Earth's mantle is constrained to be ∼70% by inferred plume heat flux and plume excess temperature in the upper mantle. In this paper, by integrating the secular cooling effects into the numerical studies, we demonstrate that the dependence of plume‐related observations on internal heating rate is not affected by secular cooling and that the plume‐related observations are only dependent on the internal heating rate and insensitive to its partitioning between radiogenic heating and secular cooling, thus confirming the conclusions of ∼70% internal heating rate from our previous numerical studies. Furthermore, we present a new analysis to constrain the internal heating rate with the plume‐related observations based on the energy balance of mantle convection. The analysis shows that the internal heating rate of the mantle has a lower bound of ∼60% to satisfy the energy balance of the mantle with current plume observations, which is consistent with the conclusions from our numerical studies.
Antarctic NAT PSC belt of June 2003: Observational validation of the mountain wave seeding hypothesis
Authors: Eckermann S. D. , Hoffmann L. , Höpfner M. , Wu D. L. , Alexander M. J.
Published: January 2009

Satellite observations of polar stratospheric clouds (PSCs) over Antarctica in June 2003 revealed small nitric acid trihydrate (NAT) particles forming suddenly along the vortex edge. Models suggest the trigger was mountain waves over the Antarctic Peninsula (AP) forming ice for NAT nucleation. We test this hypothesis by analyzing perturbations in stratospheric radiances from the Atmospheric Infrared Sounder (AIRS). AIRS data show mountain waves over the AP on 10–14 June, with no resolved wave activity before or after. Peak wave temperature amplitudes derived from independent 40 hPa channels all return values of 10–12 K, in agreement with values used to model this NAT event. These observations support a NAT wake from a small region of mountain wave activity over the AP as the source of this circumpolar NAT outbreak.
A state‐of‐the‐art picture of substorm‐associated evolution of the near‐Earth magnetotail obtained from superposed epoch analysis
Authors: Miyashita Y. , Machida S. , Kamide Y. , Nagata D. , Liou K. , Fujimoto M. , Ieda A. , Saito M. H. , Russell C. T. , Christon S. P. , Nosé M. , Frey H. U. , Shinohara I. , Mukai T. , Saito Y. , Hayakawa H.
Published: January 2009

We have obtained a state‐of‐the‐art picture of substorm‐associated evolution of the near‐Earth magnetotail and the inner magnetosphere for understanding the substorm triggering mechanism. We performed superposed epoch analysis of Geotail, Polar, and GOES data with 2‐min resolution, utilizing a total of 3787 substorms for each of which auroral breakup was determined from Polar UVI or IMAGE FUV auroral imager data. The decrease of the north‐south magnetic field associated with plasmoids and the initial total pressure decrease suggest that the magnetic reconnection first occurs in the premidnight tail, on average, at X ∼ −16 to −20 RE at least 2 min before auroral onset. The magnetic reconnection site is located near the tailward edge of a region of considerably taillike magnetic field lines and intense cross‐tail current, which extends from X ∼ −5 to −20 RE in the premidnight sector. Then the plasmoid substantially evolves tailward of X ∼ −20 RE immediately after onset. Almost simultaneously with the magnetic reconnection, the dipolarization begins first at X ∼ −7 to −10 RE 2 min before onset. The dipolarization region then expands tailward as well as in the dawn‐dusk directions and earthward. We find that the total pressure generally enhances in association with the dipolarization, with the contribution of high‐energy particles. Also, energy release is more significant between the regions of the magnetic reconnection and the initial dipolarization. The present results will be helpful as a reference guide to developing the overall picture of magnetotail evolution and studying the causal relationship between the magnetic reconnection and the dipolarization as well as detailed mechanisms of each of the two processes on the basis of multispacecraft observations.
Spherical harmonic analysis of particle velocity distribution function: Comparison of moments and anisotropies using Cluster data
Authors: Viñas Adolfo F. , Gurgiolo Chris
Published: January 2009

This paper presents a spherical harmonic analysis of the plasma velocity distribution function using high‐angular, energy, and time resolution Cluster data obtained from the PEACE spectrometer instrument to demonstrate how this analysis models the particle distribution function and its moments and anisotropies. The results show that spherical harmonic analysis produced a robust physical representation model of the velocity distribution function, resolving the main features of the measured distributions. From the spherical harmonic analysis, a minimum set of nine spectral coefficients was obtained from which the moment (up to the heat flux), anisotropy, and asymmetry calculations of the velocity distribution function were obtained. The spherical harmonic method provides a potentially effective “compression” technique that can be easily carried out onboard a spacecraft to determine the moments and anisotropies of the particle velocity distribution function for any species. These calculations were implemented using three different approaches, namely, the standard traditional integration, the spherical harmonic (SPH) spectral coefficients integration, and the singular value decomposition (SVD) on the spherical harmonic methods. A comparison among the various methods shows that both SPH and SVD approaches provide remarkable agreement with the standard moment integration method.
Boreal spring Southern Hemisphere Annular Mode, Indian Ocean sea surface temperature, and East Asian summer monsoon
Authors: Nan Sulan , Li Jianping , Yuan Xiaojun , Zhao Ping
Published: January 2009

The relationships among the boreal spring Southern Hemisphere Annular Mode (SAM), the Indian Ocean (IO) sea surface temperature (SST), and East Asian summer monsoon (EASM) are examined statistically in this paper. The variability of boreal spring SAM is closely related to the IO SST. When the SAM is in its strong positive phase in boreal spring, with low‐pressure anomalies over the south pole and high‐pressure anomalies over middle latitudes, SST over the subtropics and middle latitudes of the South Indian Ocean (SIO) increases, which persists into the summer. Following the positive SST anomalies over the subtropics and midlatitudes of the SIO, SST in the equatorial Indian Ocean and Bay of Bengal increases in summer. Moreover, the variability of SST in the equatorial Indian Ocean and Bay of Bengal is closely related to EASM. When SST in the equatorial Indian Ocean and Bay of Bengal increases, EASM tends to be weak. Therefore the IO SST may play an important role bridging boreal spring SAM and EASM. The atmospheric circulations and surface heat exchanges contribute to the SST anomalies in the SIO. When the spring SAM is in its strong positive phases, the regional Ferrel Cell weakens, and the anomalous upward motions at 20°S–30°S cause an increase of low cloud cover and downward longwave radiation flux. The surface atmospheric circulations also transport more (less) warmer (cooler) air from middle latitudes north of 50°S (high latitudes south of 60°S) into 50°S–60°S and warm the air, which reduces the temperature difference between the ocean and atmosphere and consequently reduces sensible heat flux from the ocean to atmosphere. The increased downward longwave radiation and decreased sensible heat are responsible for the SST increase in the SIO. The atmospheric circulation and surface heat flux anomalies are of opposite signs following the strong negative phases of SAM.
Size distribution time series of a polar stratospheric cloud observed above Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) (69°N) and analyzed from multiwavelength lidar measurements during winter 2005
Authors: Jumelet Julien , Bekki Slimane , David Christine , Keckhut Philippe , Baumgarten Gerd
Published: January 2009

A case study of a polar stratospheric cloud (PSC) is described using multiwavelength (355, 532, and 1064 nm) lidar measurements performed at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) on 6 December 2005. Rotational Raman signals at 529 and 530 nm are used to derive a temperature field within the cloud using the rotational Raman technique (RRT). The PSC size distributions are retrieved between 1500 and 2000 UTC through a combination of statistical filtering and best match approaches. Several PSC types were detected between 22 and 26 km during the measurement session. Liquid ternary aerosols are identified before about 1600 and after 1900 UTC typically; their averaged retrieved size distribution parameters and associated errors at the backscatter peak are: No ≈ 1–10 cm−3 (50%), rm ≈ 0.15 μm (20%), and σ ≈ 1.2 (15%). A mode of much larger particles is detected between 1600 and 1900 UTC (No ≈ 0.04 cm−3 (30%), rm ≈ 1.50 μm (15%), and σ ≈ 1.37 (10%). The different PSC types are also identified using standard semiempirical classifications, based on lidar backscatter, temperature, and depolarization. Overall, the characteristics of the retrieved size distributions are consistent with these classifications. They all suggest that these very large particles are certainly nitric acid trihydrate that could have been generated by the strong gravity wave activity visible in the temperature profiles. The results demonstrate that multiwavelength lidar data coupled to both RRT temperatures and our size distribution retrieval can provide useful additional information for identification of PSC types and for direct comparisons with microphysical model simulations.
A sequential Bayesian approach for hydrologic model selection and prediction
Authors: Hsu Kuo‐lin , Moradkhani Hamid , Sorooshian Soroosh
Published: January 2009

When a single model is used for hydrologic prediction, it must be capable of estimating system behavior accurately at all times. Multiple‐model approaches integrate several model behaviors and, when effective, they can provide better estimates than that of any single model alone. This paper discusses a sequential model fusion strategy that uses the Bayes rule. This approach calculates each model's transient posterior distribution at each time when a new observation is available and merges all model estimates on the basis of each model's posterior probability. This paper demonstrates the feasibility of this approach through case studies that fuse three hydrologic models, auto regressive with exogenous inputs, Sacramento soil moisture accounting, and artificial neural network models, to predict daily watershed streamflow.
Space Physics for Graduate Students: An Activities‐Based Approach
Authors: Gross N. A. , Arge N. , Bruntz R. , Burns A. G. , Hughes W. J. , Knipp D. , Lyon J. , McGregor S. , Owens M. , Siscoe G. , Solomon S. C. , Wiltberger M.
Published: January 2009

The geospace environment is controlled largely by events on the Sun, such as solar flares and coronal mass ejections, which generate significant geomagnetic and upper atmospheric disturbances. The study of this Sun‐Earth system, which has become known as space weather, has both intrinsic scientific interest and practical applications. Adverse conditions in space can damage satellites and disrupt communications, navigation, and electric power grids, as well as endanger astronauts.
Catalogue of Risks: Natural, Technical, Social and Health Risks
Authors: Ebi Kristie L.
Published: January 2009

Financial, geophysical, and terrorist‐related disasters have been headline news in the past few months. As amply demonstrated on a regular basis, the recognition and evaluation of risks are skills that could be more widespread. As such, Proske's Catalogue of Risks is timely and of potential interest.

The book is a revised and expanded version of an earlier German publication that aims to provide an encyclopedic discussion of issues related to risks and disasters, with a goal of facilitating an understanding of the components and assessment of risk. The book includes chapters that discuss the difficulty of coming to a consensus on a definition of risk, a comprehensive range of risks and disasters, objective risk measures, subjective risk judgment, quality of life measures, and legal aspects of risk. The book ends with an example of applying the concepts discussed to ship impacts against bridges.
The Relationship between Physical Activity and Body Mass Index: Issues in Model Specification
Authors: Tiruneh Gizachew
Published: January 2009

*Objective:*

To investigate the best statistical models that describe the effect of physical activity on BMI.*Design:* Cross-sectional analyses of physical activity and BMI data. Subjects: 107 obese, overweight, and healthy college students (mean duration of physical activity for the normal, overweight, and obese students: 89, 59, and 24 months, respectively; mean BMI for the normal, overweight, and obese students: 21.61, 27.07, and 35.54 kg/m^2^, respectively).*Measurements:* Inverse linear, inverse logarithmic, and inverse logistics models were used to analyze survey data for physical activity (measured by both frequency and duration of exercise) and BMI. Gender, age, and physical intensity variables were also statistically controlled.

*Results:*

Coefficients of determination, r-squared, showed the inverse logarithmic model is more accurate in describing the effect of physical activity on BMI than is the inverse linear model. The inverse logistic method also showed physical activity affects BMI.

*Conclusions:*

Although the inverse logarithmic method can be used in some cases, the inverse logistic model seems to be theoretically and empirically best suited in describing the relationship between physical activity and body weight.
Interaction of Au with CeO2(111): A photoemission study
Authors: Škoda M. , Cabala M. , Matolínová I. , Prince K. C. , Skála T. , Šutara F. , Veltruská K. , Matolín V.
Published: January 2009

We have studied the adsorption of low dimensional gold on ceria, produced by evaporation onto the surface. The interaction of gold with CeO2(111) layers was investigated with x-ray photoemission spectroscopy, ultraviolet photoemission spectroscopy, and resonant photoelectron spectroscopy (RPES). Gold was deposited in steps onto a 1.5 nm thick CeO2(111) layer epitaxially grown on a Cu(111) substrate. The RPES showed a partial Ce4+→Ce3+ reduction, observed as a resonant enhancement of the 4f level of the Ce3+ species. This can be explained by possible creation of a new Au+ ionic state. The observed effects are stronger for Au deposition at room temperature than at 250 °C. The obtained results are in agreement with already published density functional theory calculations reporting weakening of bond between the oxygen and the Ce atoms in ceria caused by the presence of gold.
Fourier transform microwave spectroscopy of HZnCN(X Σ1+) and ZnCN(X Σ2+)
Authors: Sun M. , Apponi A. J. , Ziurys L. M.
Published: January 2009

The pure rotational spectrum of HZnCN in its X Σ1+ electronic state has been recorded using pulsed Fourier transform microwave (FTMW) techniques in the frequency range 7–39 GHz—the first spectroscopic study of this species in the gas phase. The FTMW spectrum of ZnCN(X Σ2+) has been measured as well. A new FTMW spectrometer with an angled beam and simplified electronics, based on a cryopump, was employed for these experiments. The molecules were created in a dc discharge from a gas mixture of Zn(CH3)2 and cyanogen (1% D2 for the deuterated analogs), diluted with argon, that was expanded supersonically from a pulsed nozzle. Seven isotopologues of HZnCN arising from zinc, deuterium, and C13 substitutions were studied; for every species, between three and five rotational transitions were recorded, each consisting of numerous hyperfine components arising from nitrogen, and in certain cases, deuterium, and 67-zinc nuclear spins. Four transitions of ZnCN were measured. From these data, rotational, nuclear spin-rotation, and quadrupole coupling constants have been determined for HZnCN, as well as rotational, and magnetic and quadrupole hyperfine parameters for the ZnCN radical. The bond lengths determined for HZnCN are rH–Zn=1.495 Å, rZn–C=1.897 Å, and rC–N=1.146 Å, while those for ZnCN are rZn–C=1.950 Å and rC–N=1.142 Å. The zinc-carbon bond length thus shortens with the addition of the H atom. The nitrogen quadrupole coupling constant eqQ was found to be virtually identical in both cyanide species (−5.089 and −4.931 MHz), suggesting that the electric field gradient across the N nucleus is not influenced by the H atom. The quadrupole constant for the Z67n nucleus in HZ67nCN is unusually large relative to that in Z67nF (−104.578 versus −60 MHz), evidence that the bonding in the cyanide has more covalent character than in the fluoride. This study additionally suggests that hydrides of other metal cyanide species are likely candidates for high resolution spectroscopic investigations.
Characterization of anisotropic poly(vinyl alcohol) hydrogel by small- and ultra-small-angle neutron scattering
Authors: Hudson Stephen D. , Hutter Jeffrey L. , Nieh Mu-Ping , Pencer Jeremy , Millon Leonardo E. , Wan Wankei
Published: January 2009

Poly(vinyl alcohol) (PVA) hydrogels are formed from PVA solution when physical cross-links form during freeze/thaw cycling. By applying a stress during the freeze/thaw process, PVA hydrogels with anisotropic mechanical properties are produced. We have used small- and ultra-small-angle neutron scattering to study the structure at length scales of 2 nm to 10 μm. By supplementing the neutron data with data from atomic force microscopy, we have probed a large range of length scales within which structural changes responsible for bulk anisotropy occur. We model the gel as interconnected PVA blobs of size 20–50 nm arranged in fractal aggregates extending to micrometers or tens of micrometers. Bulk mechanical anisotropy appears to be due to the alignment of blobs and connections between blobs. This information is essential for tailoring mechanical properties for applications where anisotropy is desirable such as to match the properties of natural tissue in coronary grafts and to control diffusive properties in active wound dressings.
Structural relaxations of phospholipids and water in planar membranes
Authors: Svanberg C. , Berntsen P. , Johansson A. , Hedlund T. , Axén E. , Swenson J.
Published: January 2009

We have used dielectric spectroscopy and temperature modulated differential scanning calorimetry (TMDSC) to investigate the structural relaxation processes and phase transitions of water and lipids in multilamellar, planar phospholipids. At low hydration levels we observe the main structural relaxation related to the glass transition of the phospholipids. With increasing water content a more pronounced pretransition, attributed to a gel to ripple phase transition, is observed in the TMDSC data. In the proximity of this pretransition, a distinct change in the temperature dependence or alternatively a bifurcation into two processes is observed in the dielectric data. Around this temperature a crossover in the long-range ionic conductivity across the membranes is also observed, which is one of the key parameters for biological membranes. Thus, the major dynamical changes do not occur at the main, i.e., the gel to liquid structural phase transition, but at a pretransition that occurs roughly 20 K below the main transition.
UV excitation and radiationless deactivation of imidazole
Authors: Barbatti Mario , Lischka Hans , Salzmann Susanne , Marian Christel M.
Published: January 2009

The vertical spectrum and the radiationless decay of imidazole have been investigated theoretically. Benchmark calculations were performed employing different methods and levels. Four different conical intersections were characterized and the reaction paths connecting the Franck–Condon region to them were computed. Two of the conical intersections show puckered structures while the other two show NH and ring dissociation patterns. The ππ∗/S0 N1-puckered conical intersection is connected to the planar πσ∗/S0 ring-opened conical intersection by a branch of the crossing seam. After excitation into the first π1π∗ state, the internal conversion can occur either in this branch of crossing seam or along the NH-dissociation path.
Photodissociation dynamics of the A Σ2+ state of SH and SD radicals
Authors: Rose R. A. , Orr-Ewing A. J. , Yang C.-H. , Vidma K. , Groenenboom G. C. , Parker D. H.
Published: January 2009

Atomic sulfur products from predissociation of the lowest rotational states of SH/SD A Σ2+ (v′=0,1,2) are studied using velocity map imaging. The dissociation process, which is slow compared to rotation, is dominated by interference effects due to predissociation of states with low rotation quantum numbers prepared by photoexcitation using overlapping transitions of different parities. The measured product angular distributions can be modeled using the methods presented recently by Kim et al. [J. Chem. Phys. 125, 133316 (2006)]. The S(P3J) (2+1) resonance enhanced multiphoton ionization scheme used in the detection step of the experiment is sensitive to the angular momentum polarization of the atomic fragments. S(P3J), J=2,1,0, fine-structure yields, angular distributions, and atom polarization parameters are reported. Strong polarization of the S(P32,1) products was observed along with a weak sensitivity of the branching ratio to excess energy and a full insensitivity of the atomic product polarization to excess energy. None of the data fit the predictions of either adiabatic or diabatic photodissociation, emphasizing the need for a fully quantum treatment.
Multidimensional Langevin modeling of biomolecular dynamics
Authors: Hegger Rainer , Stock Gerhard
Published: January 2009

A systematic computational approach to describe the conformational dynamics of biomolecules in reduced dimensionality is presented. The method is based on (i) the decomposition of a high-dimensional molecular dynamics trajectory into a few “system” and (many) “bath” degrees of freedom and (ii) a Langevin simulation of the resulting model. Employing principal component analysis, the dimension of the system is chosen such that it contains all slow large-amplitude motions of the molecule, while the bath coordinates only account for its high-frequency fluctuations. It is shown that a sufficiently large dimension of the model is essential to ensure a clear time scale separation of system and bath variables, which warrants the validity of the memory-free Langevin equation. Applying methods from nonlinear time series analysis, a practical Langevin algorithm is presented which performs a local estimation of the multidimensional Langevin vector fields describing deterministic drift and stochastic driving. Adopting a 800 ns molecular dynamics simulation of the folding of heptaalanine in explicit water, it is shown that a five-dimensional Langevin model correctly reproduces the structure and conformational dynamics of the system. The virtues and limits of the approach are discussed in some detail.
A multiscale approach for modeling the early stage growth of single and multiwall carbon nanotubes produced by a metal-catalyzed synthesis process
Authors: Elliott James A. , Hamm Marc , Shibuta Yasushi
Published: January 2009

A parametrized mesoscale model for the early stage growth of isolated single or multiwall carbon nanotubes (CNTs) has been developed in order to investigate the effects of metal catalyst particle size and composition on CNT growth mechanism during synthesis via a substrate-supported, catalytic chemical vapor deposition process. The model is based on a coarse-grained graphene sheet, represented by a two-dimensional simply connected triangular mesh, with parameters for the surface curvature, bond stretching, carbon-carbon interaction, and carbon-catalyst interaction determined by classical molecular dynamics simulations using a bond-order potential derived from ab initio calculations. The mesoscale simulations show that the initial type of CNT growth is strongly influenced by the surface interaction energy between the graphene sheet and metal catalyst particle, rate of carbon deposition, and particle size. As expected, single wall tubes are produced from small catalyst particles at low deposition rates, but increasing the strength of carbon-catalyst interaction energy or carbon deposition rate results in double or even multiwall CNT structures, formed by folding or involution of the graphene sheet. For the range of model parameters investigated, all single wall CNTs with a diameter greater than 6.6 nm exhibited a kink-collapse transition once a certain critical tube length was reached.
Nature of Ar bonding to small Con+ clusters and its effect on the structure determination by far-infrared absorption spectroscopy
Authors: Gehrke Ralf , Gruene Philipp , Fielicke André , Meijer Gerard , Reuter Karsten
Published: January 2009

Far-infrared vibrational spectroscopy by multiple photon dissociation has proven to be a very useful technique for the structural fingerprinting of small metal clusters. Contrary to previous studies on cationic V, Nb, and Ta clusters, measured vibrational spectra of small cationic cobalt clusters show a strong dependence on the number of adsorbed Ar probe atoms, which increases with decreasing cluster size. Focusing on the series Co4+ to Co8+ we therefore use density-functional theory to analyze the nature of the Ar–Con+ bond and its role for the vibrational spectra. In a first step, energetically low-lying isomer structures are identified through first-principles basin-hopping sampling runs and their vibrational spectra are computed for a varying number of adsorbed Ar atoms. A comparison of these fingerprints with the experimental data enables in some cases a unique assignment of the cluster structure. Independent of the specific low-lying isomer, we obtain a pronounced increase in the Ar binding energy for the smallest cluster sizes, which correlates nicely with the observed increased influence of the Ar probe atoms on the IR spectra. Further analysis of the electronic structure motivates a simple electrostatic picture that not only explains this binding energy trend but also rationalizes the stronger influence of the rare-gas atom compared to the preceding studies by the small atomic radius of Co.
Response to “Comment on ‘Residual multiparticle entropy does not generally change sign near freezing’ ” [J. Chem. Phys. 130, 037101 (2009)]
Authors: Krekelberg William P. , Shen Vincent K. , Errington Jeffrey R. , Truskett Thomas M.
Published: January 2009

We respond to a Comment on our recent paper [J. Chem. Phys.128, 161101 (2008)] regarding the connection between the change in sign of the residual multiparticle entropy and the freezing transition.
Condition on the Kohn–Sham kinetic energy and modern parametrization of the Thomas–Fermi density
Authors: Lee Donghyung , Constantin Lucian A. , Perdew John P. , Burke Kieron
Published: January 2009

We study the asymptotic expansion of the neutral-atom energy as the atomic number Z→∞, presenting a new method to extract the coefficients from oscillating numerical data. Recovery of the correct expansion yields a condition on the Kohn–Sham kinetic energy that is important for the accuracy of approximate kinetic energy functionals for atoms, molecules, and solids. For example, this determines the small gradient limit of any generalized gradient approximation and conflicts somewhat with the standard gradient expansion. Tests are performed on atoms, molecules, and jellium clusters using densities constructed from Kohn–Sham orbitals. We also give a modern, highly accurate parametrization of the Thomas–Fermi density of neutral atoms.
Mode-selective vibrational redistribution after spectrally selective N–H stretching mode excitation in intermolecular hydrogen bonds
Authors: Kozich V. , Dreyer J. , Werncke W.
Published: January 2009

Mode-selective vibrational redistribution after spectrally selective excitation within the highly structured N–H stretching band of the 7-azaindole dimer was observed by subpicosecond infrared-pump/anti-Stokes Raman-probe spectroscopy. Measurements after relaxation of the N–H stretching vibration indicate ultrafast initial population transfer to vibrations with pronounced N–H bending character. From these modes energy is transferred to modes of frequencies below 1000 cm−1 on a slower time scale of about 3 ps. Tuning the spectrally narrow infrared excitation to the different substructures of the N–H stretching band influences the distribution of populations between the fingerprint modes. Their relative populations are correlated with the contributions of the modes forming the different coupled combination tones of the N–H stretching band. These results provide experimental support to a Fermi resonance model previously used for simulations of the N–H stretching infrared absorption band shape and insight into relaxation from the initially excited combination bands.
A Simple and Economic Synthesis of Propargylamines by CuI-Catalyzed Three-Component Coupling Reaction with Succinic Acid as Additive
Authors: Ren Gerui , Zhang Jinli , Duan Zheng , Cui Mengjun , Wu Yangjie
Published: January 2009

A practical and efficient method was developed for the synthesis of propargylamines in a one-pot procedure from aldehydes, amines, and alkynes by using CuI as catalyst and succinic acid as additive. By using this protocol, a wide range of propargylamines was obtained in high yields.
Microwave-Assisted Synthesis of Tetracyclic 2,5-Diketopiperazines on a Soluble Polymer Support: A Structural Analogue of Tadalafil
Authors: Chang Wong-Jin , Chanda Kaushik , Sun Chung-Ming
Published: January 2009

Structural analogues of tadalafil that contain two diversity points have been synthesized from a soluble polymer support employing a Pictet–Spengler reaction using focussed microwave irradiation. Polymer-bound deprotected tryptophan reacts with various aldehydes to generate the tetrahydro-β-carbolines on the support. Subsequently immobilized tetrahydro-β-carboline underwent a highly efficient intramolecular N-heterocyclization in a traceless fashion from various in-situ generated α-alkyl and heteroalkyl amides in two steps to generate tetracyclic 2,5-diketopiperazines in high purity. All the compounds were isolated as cis and trans isomers with good yields.