bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of electrosense in the feeding behavior of sturgeons
Authors: ZHANG Xuguang , SONG Jiakun , FAN Chunxin , GUO Hongyi , WANG Xiaojie , BLECKMANN Horst
Published: March 2012

The electro‐receptive lateral line system appeared early in the evolutionary history of fish. Sturgeons, members of the primitive Chondrostei group, are known for their electroreceptors (ampullae of Lorenzini) on the head, which are thought to be sensitive to weak electric fields in aquatic environments and involved in feeding, mating and migration. Here, we report the results of a set of behavioral and electrophysiological experiments designed to determine the function and characteristics of the electrosense in cultured sturgeons. The results showed Siberian sturgeon (Acipenser baerii Brandt, 1869) feeding striking at bio‐electric fields produced by living feed‐fish enclosed in a gel chamber and at the corrosion field produced by metal rods. With an electric stimulus that mimics the bio‐electric fields produced by living prey, the relative discharge rate of electrosensory neurons in the dorsal octavolateralis nucleus (DON) was modulated by and phase‐locked to sinusoidal stimulus and some units showed selectivity for dipolar direction in white sturgeon (Acipenser transmontanus Richardson, 1836). This is the first study to provide the empirical evidence correlating with electrosensory behaviors and electrophysiological responses in cultured sturgeons, and suggesting that electrosense does play an innate role in feeding behavior of sturgeon. We believe this will have important implications for protecting sturgeons in the wild.
Differences in mating behavior lead to asymmetric mating interactions and consequential changes in sex ratio between an invasive and an indigenous whitefly
Authors: LUAN Junbo , LIU Shusheng
Published: March 2012

The invasive B whitefly and the indigenous ZHJ2 whitefly in China of the Bemisia tabaci complex represent two previously allopatric cryptic species. Laboratory experiments have shown that the invasive B can displace the indigenous ZHJ2. Here, we observed the mating behavior and mating interactions between B and ZHJ2 to elucidate the behavioral mechanisms underlying their competition. The 2 species are able to mate with each other, although at a significantly lower frequency than that between males and females within the same species. Heterospecifically‐mated females produce only male progeny, indicating reproductive isolation. Heterospecific mating had only a marginal effect on reproduction of females in either species. Detailed observations on mating interactions between the 2 species showed that B had higher sexual activity than ZHJ2. B males were more likely to interrupt courtships initiated by rival males than ZHJ2 males. Compared with ZHJ2 males, B males were also more likely to successfully interrupt courtships initiated by rival heterospecific males than by males of the same species. In addition, B males guarded B females post‐copulation, whereas ZHJ2 males did not. When the 2 species co‐occurred, the behavioral differences and interactions between them resulted in an increased proportion of females produced in the offspring of B but reduced proportion of females in the progeny of ZHJ2. These asymmetric mating interactions might be an important mechanism underlying the displacement of ZHJ2 by B. Our study shows that reproductive interference might contribute to the competitive exclusion between closely related species during biological invasions.
Wound healing during hibernation by black bears (Ursus americanus) in the wild: elicitation of reduced scar formation
Authors: IAIZZO Paul A. , LASKE Timothy G. , HARLOW Henry J. , McCLAY Carolyn B. , GARSHELIS David L.
Published: March 2012

Even mildly hypothermic body or limb temperatures can retard healing processes in mammals. Despite this, we observed that hibernating American black bears (Ursus americanus Pallas, 1780) elicit profound abilities in mounting inflammatory responses to infection and/or foreign bodies. In addition, they resolve injuries during hibernation while maintaining mildly hypothermic states (30–35 °C) and without eating, drinking, urinating or defecating. We describe experimental studies on free‐ranging bears that document their abilities to completely resolve cutaneous cuts and punctures incurred during or prior to hibernation. We induced small, full‐thickness cutaneous wounds (biopsies or incisions) during early denning, and re‐biopsied sites 2–3 months later (near the end of denning). Routine histological methods were used to characterize these skin samples. All biopsied sites with respect to secondary intention (open circular biopsies) and primary intention (sutured sites) healed, with evidence of initial eschar (scab) formation, completeness of healed epidermis and dermal layers, dyskeratosis (inclusion cysts), and abilities to produce hair follicles. These healing abilities of hibernating black bears are a clear survival advantage to animals injured before or during denning. Bears are known to have elevated levels of hibernation induction trigger (delta‐opioid receptor agonist) and ursodeoxycholic acid (major bile acid within plasma, mostly conjugated with taurine) during hibernation, which may relate to these wound‐healing abilities. Further research as to the underlying mechanisms of wound healing during hibernation could have applications in human medicine. Unique approaches may be found to improve healing for malnourished, hypothermic, diabetic and elderly patients or to reduce scarring associated with burns and traumatic injuries.
Accidental Exposure to UV Radiation Produced by Germicidal Lamp: Case Report and Risk Assessment
Authors: Zaffina Salvatore , Camisa Vincenzo , Lembo Marco , Vinci Maria Rosaria , Tucci Mario Graziano , Borra Massimo , Napolitano Antonio , Cannatà Vittorio
Published: March 2012

Ultraviolet radiation is known to cause both benefits and harmful effects on humans. The adverse effects mainly involve two target organs, skin and eye, and can be further divided into short‐ and long‐term effects. The present case report describes an accidental exposure of two health‐care workers to ultraviolet radiation produced by a germicidal lamp in a hospital pharmacy. The germicidal lamp presented a spectrum with an intense UV‐C component as well as a modest UV‐B contribution. Overexposure to UV‐C radiation was over 100 times as large as the ICNIRP exposure limits. A few hours after the exposure, the two subjects reported symptoms of acute UV injury and both of them continued having significant clinical signs for over 2 years. In this study, we describe acute and potentially irreversible effects caused by high UV exposure. In addition, we present the results of risk assessment by occupational exposure to germicidal lamps.
The role of leptin in glucose homeostasis
Authors: Denroche Heather C , Huynh Frank K , Kieffer Timothy J
Published: March 2012

The fat‐derived hormone, leptin, is well known to regulate body weight. However, there is now substantial evidence that leptin also plays a primary role in the regulation of glucose homeostasis, independent of actions on food intake, energy expenditure or body weight. As such, leptin might have clinical utility in treating hyperglycemia, particularly in conditions of leptin deficiency, such as lipodystrophy and diabetes mellitus. The mechanisms through which leptin modulates glucose metabolism have not been fully elucidated. Leptin receptors are widely expressed in peripheral tissues, including the endocrine pancreas, liver, skeletal muscle and adipose, and both direct and indirect leptin action on these tissues contributes to the control of glucose homeostasis. Here we review the role of leptin in glucose homeostasis, along with our present understanding of the mechanisms involved. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00203.x, 2012)
Lateral-Torsional Stability Boundaries for Polygonally Depth-Tapered Strip Cantilevers Under Multi-Parameter Point Load Systems—An Analytical Approach
Authors: Andrade Anísio , Challamel Noël , Providência Paulo , Camotim Dinar
Published: March 2012

This paper reports an analytical study on the elastic lateral-torsional buckling behavior of strip cantilevers (i) whose depth is given by a monotonically decreasing polygonal function of the distance to the support and (ii) which are subjected to an arbitrary number of independent conservative point loads, all acting in the same “downward” direction. The study is conducted on the basis of a one-dimensional (beam) mathematical model. A specialized model problem, consisting of a two-segment cantilever acted by two loads, applied at the free end and at the junction between segments, is first considered in detail for it “contains all the germs of generality”. It is shown that the governing differential equations can be integrated in terms of confluent hypergeometric functions or Bessel functions (themselves special cases of confluent hypergeometric functions). This allows us to establish exactly the characteristic equation for this structural system, which implicitly defines its stability boundary. Moreover, it is shown that the methods used to solve the model problem also apply to the general problem. A couple of parametric illustrative examples are discussed. Some analytical solutions are compared with the results of shell finite element analyses—a good agreement is found.
Hierarchical Genetic Organization of Human Cortical Surface Area
Authors: Chen Chi-Hua , Gutierrez E. D. , Thompson Wes , Panizzon Matthew S. , Jernigan Terry L. , Eyler Lisa T. , Fennema-Notestine Christine , Jak Amy J. , Neale Michael C. , Franz Carol E. , Lyons Michael J. , Grant Michael D. , Fischl Bruce , Seidman Larry J. , Tsuang Ming T. , Kremen William S. , Dale Anders M.
Published: March 2012

Building the Brain

Brain connectivity is often described as a network of discrete independent cables analogous to a switchboard, but how is the physical structure of the brain constructed (see the Perspective by

Zilles and Amunts

)?

Wedeen
et al.

(p.
1628
) used high-resolution diffusion tensor imaging in humans and four species of nonhuman primates to identify and compare the geometric structure of large fiber tracts in the brain. Fiber tracts followed a highly constrained and regular geometry, which may provide an efficient solution for pathfinding during ontogenetic development. Much of development occurs through elaboration and assembly of semiautonomous building blocks.

Chen
et al.

(p.
1634
) applied statistical analysis to the form of the human cortex in brain-imaging studies that compared more than 400 di- and mono-zygotic twins. The findings suggest that the structure of the human cortex is defined by genetics.
Ecological Context Influences Epidemic Size and Parasite-Driven Evolution
Authors: Duffy Meghan A. , Ochs Jessica Housley , Penczykowski Rachel M. , Civitello David J. , Klausmeier Christopher A. , Hall Spencer R.
Published: March 2012

Cost-Benefit Analysis

Mounting resistance to infection is costly, requires energetic input, and may thus compromise fecundity.

Duffy
et al.

(p.
1636
; see the cover) tested the relationships between productivity, predation, and mortality in a combination of observations of a natural lake and an experimental replica of a clonal zooplankton-parasitic yeast population. In the wild, epidemics of the yeast could exceed 60% and cause significant host mortality. In this situation, the clonal zooplankton host faces the physiological dilemma of either increasing resistance to deal with infection or of safeguarding fecundity. Zooplankton that feed quickly can reproduce quickly, but also end up ingesting more yeast spores. However, because fish tend to cull infected hosts, fish predation counters infection. Ultimately, both wild and model systems showed that lakes with high productivity (more nitrogen) and/or few fish supported greater epidemics of yeast and more resistant hosts, whereas less productive lakes, or those with more fish, had smaller epidemics and hosts with higher susceptibility to the yeast.
To Protect Human Subjects, Review What Was Done, Not Proposed
Authors: Klitzman Robert , Appelbaum Paul S.
Published: March 2012

Retrospective review could improve the efficiency—and perhaps the effectiveness—of human subjects research oversight.
How Smart Is Your Home?
Authors: Cook Diane J.
Published: March 2012

Technical advances are bringing intelligent homes that respond to residents' needs and wishes within reach.
Integrated Electromicrobial Conversion of CO
2
to Higher Alcohols
Authors: Li Han , Opgenorth Paul H. , Wernick David G. , Rogers Steve , Wu Tung-Yun , Higashide Wendy , Malati Peter , Huo Yi-Xin , Cho Kwang Myung , Liao James C.
Published: March 2012

An engineered microbe transforms carbon dioxide into a prospective liquid fuel in tandem with electrical power rather than light.
hnRNP C Tetramer Measures RNA Length to Classify RNA Polymerase II Transcripts for Export
Authors: McCloskey Asako , Taniguchi Ichiro , Shinmyozu Kaori , Ohno Mutsuhito
Published: March 2012

Choosing the Right Path

RNA molecules are synthesized in the cell nucleus, yet many have to be moved to the cytoplasm to be processed and/or to effect their function. Different classes of RNA are transported from the nucleus by different transport systems. Messenger RNAs (mRNAs) and uridine-rich small nuclear RNAs (U snRNAs) are transcribed by RNA polymerase II and are capped and bound by the cap-binding machinery in the nucleus but are exported by different protein complexes. The feature that distinguishes the two classes of RNA is their length: U snRNAs are short and mRNAs are long. Using an in vitro system and human tissue culture cells,

McCloskey
et al.

(p.
1643
) show that the length of the RNAs is measured by the heterogeneous nuclear ribonicleoprotein (hnRNP) C tetrameric protein complex. The hnRNP C cannot bind to the short U snRNAs, allowing the U snRNA-specific export adaptor protein, PHAX, to bind and mediate export. Longer mRNAs are bound by hnRNP C, which prevents the binding of PHAX, thus identifying these RNAs for export from the nucleus via the mRNA pathway.
Response to Comments on “Disentangling the Drivers of β Diversity Along Latitudinal and Elevational Gradients”
Authors: Kraft Nathan J. B. , Sanders Nathan J. , Stegen James C. , Anderson Marti J. , Crist Thomas O. , Cornell Howard V. , Vellend Mark , Chase Jonathan M. , Comita Liza S. , Davies Kendi F. , Freestone Amy L. , Harrison Susan P. , Inouye Brian D. , Myers Jonathan A. , Swenson Nathan G.
Published: March 2012

Qian
et al
. and Tuomisto and Ruokolainen critique our analyses of elevational and latitudinal variation in tree diversity. We address their points by reanalyzing different subsets of our data and by clarifying certain misconceptions, and reiterate that gradients in β diversity can be explained in the elevational and latitudinal tree data sets by variation in the size of species pools.
New Lens Offers Scientist A Brighter Outlook
Authors: Saini Angela
Published: March 2012

Embittered by a past fight with a commercial microscope maker, a British scientist hopes to revolutionize imaging with a new microscope he will build and sell himself.
Attenuation of Chikungunya Virus Vaccine Strain 181/Clone 25 Is Determined by Two Amino Acid Substitutions in the E2 Envelope Glycoprotein
Authors: Gorchakov Rodion , Wang Eryu , Leal Grace , Forrester Naomi L. , Plante Kenneth , Rossi Shannan L. , Partidos Charalambos D. , Adams A. Paige , Seymour Robert L. , Weger James , Borland Erin M. , Sherman Michael B. , Powers Ann M. , Osorio Jorge E. , Weaver Scott C.
Published: March 2012

Chikungunya virus (CHIKV) is the mosquito-borne alphavirus that is the etiologic agent of massive outbreaks of arthralgic febrile illness that recently affected millions of people in Africa and Asia. The only CHIKV vaccine that has been tested in humans, strain 181/clone 25, is a live-attenuated derivative of Southeast Asian human isolate strain AF15561. The vaccine was immunogenic in phase I and II clinical trials; however, it induced transient arthralgia in 8% of the vaccinees. There are five amino acid differences between the vaccine and its parent, as well as five synonymous mutations, none of which involves
cis
-acting genome regions known to be responsible for replication or packaging. To identify the determinants of attenuation, we therefore tested the five nonsynonymous mutations by cloning them individually or in different combinations into infectious clones derived from two wild-type (WT) CHIKV strains, La Reunion and AF15561. Levels of virulence were compared with those of the WT strains and the vaccine strain in two different murine models: infant CD1 and adult A129 mice. An attenuated phenotype indistinguishable from that of the 181/clone 25 vaccine strain was obtained by the simultaneous expression of two E2 glycoprotein substitutions, with intermediate levels of attenuation obtained with the single E2 mutations. The other three amino acid mutations, in nsP1, 6K, and E1, did not have a detectable effect on CHIKV virulence. These results indicate that the attenuation of strain 181/clone 25 is mediated by two point mutations, explaining the phenotypic instability observed in human vaccinees and also in our studies.
Ultrastructural Visualization of Individual Tegument Protein Dissociation during Entry of Herpes Simplex Virus 1 into Human and Rat Dorsal Root Ganglion Neurons
Authors: Aggarwal Anupriya , Miranda-Saksena Monica , Boadle Ross A. , Kelly Barbara J. , Diefenbach Russell J. , Alam Waafiqa , Cunningham Anthony L.
Published: March 2012

Herpes simplex virus 1 (HSV-1) enters neurons primarily by fusion of the viral envelope with the host cell plasma membrane, leading to the release of the capsid into the cytosol. The capsid travels via microtubule-mediated retrograde transport to the nuclear membrane, where the viral DNA is released for replication in the nucleus. In the present study, the composition and kinetics of incoming HSV-1 capsids during entry and retrograde transport in axons of human fetal and dissociated rat dorsal root ganglia (DRG) neurons were examined by wide-field deconvolution microscopy and transmission immunoelectron microscopy (TIEM). We show that HSV-1 tegument proteins, including VP16, VP22, most pUL37, and some pUL36, dissociated from the incoming virions. The inner tegument proteins, including pUL36 and some pUL37, remained associated with the capsid during virus entry and transit to the nucleus in the neuronal cell body. By TIEM, a progressive loss of tegument proteins, including VP16, VP22, most pUL37, and some pUL36, was observed, with most of the tegument dissociating at the plasma membrane of the axons and the neuronal cell body. Further dissociation occurred within the axons and the cytosol as the capsids moved to the nucleus, resulting in the release of free tegument proteins, especially VP16, VP22, pUL37, and some pUL36, into the cytosol. This study elucidates ultrastructurally the composition of HSV-1 capsids that encounter the microtubules in the core of human axons and the complement of free tegument proteins released into the cytosol during virus entry.
Trends in the coverage of ‘universal’ child health reviews: observational study using routinely available data
Authors: Wood Rachael , Stirling Alex , Nolan Claire , Chalmers Jim , Blair Mitch
Published: March 2012

Objectives

Universally offered child health reviews form the backbone of the UK child health programme. The reviews assess children's health, development and well-being and facilitate access to additional support as required. The number of reviews offered per child has been reduced over recent years to allow more flexible provision of support to families in need: equitable coverage of the remaining reviews is therefore particularly important. This study assessed the coverage of universal child health reviews, with an emphasis on trends over time and inequalities in coverage by deprivation.

Design

Assessment of the coverage of child health reviews by area-based deprivation using routinely available data. Supplementary audit of the quality of the routine data source used.

Setting

Scotland.

Participants

Two cohorts of around 40 000 children each. The cohorts were born in 1998/1999 and 2007/2008 and eligible for the previous programme of five and the current programme of two preschool reviews, respectively.

Outcome measures

Coverage of the specified child health reviews for the whole cohorts and by deprivation.

Results

Coverage of the 10 day review is high (99%), but it progressively declines for reviews at older ages (86% for the 39–42 month review). Coverage is lower in children living in the most deprived areas for all reviews, and the discrepancy progressively increases for reviews at older ages (78% and 92% coverage for the 39–42 month review in most and least deprived groups). Coverage has been stable over time: it has not increased for the remaining reviews after reduction in the number of reviews provided.

Conclusions

The inverse care law continues to operate in relation to ‘universal’ child health reviews. Equitable uptake of reviews is important to ensure maximum likely impact on inequalities in children's outcomes.
Roles of vitamin A status and retinoids in glucose and fatty acid metabolism
Authors: Zhao Shi , Li Rui , Li Yang , Chen Wei , Zhang Yan , Chen Guoxun
Published: March 2012

The rising prevalence of metabolic diseases, such as obesity and diabetes, has become a public health concern. Vitamin A (VA, retinol) is an essential micronutrient for a variety of physiological processes, such as tissue differentiation, immunity, and vision. However, its role in glucose and lipid metabolism has not been clearly defined. VA activities are mediated by the metabolite of retinol catabolism, retinoic acid, which activates the retinoic acid receptor and retinoid X receptor (RXR). Since RXR is an obligate heterodimeric partner for many nuclear receptors involved in metabolism, it is reasonable to assume that VA status and retinoids contribute to glucose and lipid homeostasis. To date, the impacts of VA and retinoids on energy metabolism in animals and humans have been demonstrated in some basic and clinical investigations. This review summarizes the effects of VA status and retinoid treatments on metabolism of the liver, adipocytes, pancreatic β-cells, and skeletal muscle. It proposes a mechanism by which the dietary and hormonal signals converge on the promoter of sterol regulatory element-binding protein 1c gene to induce its expression, and in turn, the expression of lipogenic genes in hepatocytes. Future research projects relevant to the VA’s roles in metabolic diseases are also discussed.
Seismic table investigation of the effect of inclusions on the cyclic behaviour of tailings
Authors: Pépin Nicolas , Aubertin Michel , James Michael
Published: March 2012

When subjected to cyclic loadings, such as those induced by earthquakes, hard rock mine tailings may undergo liquefaction. Such a response can be damaging to the tailings impoundment and, in the case of a breach, to the surroundings. Means must thus be considered to control or alleviate the risks due to liquefaction. This paper presents the main results of a laboratory investigation that focussed on the dynamic behaviour of tailings due to cyclic loading on a seismic table. Different conditions were investigated to assess the influence of various factors, including tailings density and the presence of rigid and (or) drainage inclusions. The main results obtained during the tests conducted on the tailings, with and without inclusions, are presented and discussed with an emphasis on the development of excess porewater pressures. The main limitations of this experimental work are also discussed. These results show that inclusions can have a significant effect on the dynamic response of the tailings and on the occurrence of liquefaction.
Kinetic study on the linalool ozonolysis reaction in the atmosphere
Authors: Sun Xiaomin , Zhang Chenxi , Zhao Yuyang , Bai Jing , He Maoxia
Published: March 2012

In the atmosphere, linalool ozonolysis will generate a series of oxidation products and then form particles through nucleation. In this study, the linalool ozonolysis mechanisms were studied and some of the main products detected from experiment are verified. The Rice–Ramsperger–Kassel–Marcus (RRKM) theory and the canonical variational transition state theory (CVT) with small curvature tunneling effect (SCT) are used to calculate rate constants over the temperature range of 200∼800 K. The total rate constant for the reaction of ozone with linalool is 4.50 × 10−16 cm3 molecule–l s–l, and the addition of ozone to (CH3)2C=CH– is the main ozone addition position. Furthermore, the Arrhenius formulas are fitted and the lifetimes of reaction species in the troposphere are discussed for the first time. The total atmospheric lifetime of linalool relative to O3 is 2.30 h. The O3-initiated atmospheric lifetimes of P1, P3, and P6 are 2.64 months, 16.67 days, and 15.5 h, respectively.
Complete basis set, hybrid-density functional theory study, and natural bond orbital interpretations of the conformational behavior of halocarbonyl, thiocarbonyl, and selenocarbonyl isocyanates
Authors: Mousavi Seiedeh Negar , Nori-Shargh Davood , Yahyaei Hooriye , Frahani Kobra Mazrae
Published: March 2012

Complete basis set CBS-QB3, hybrid-density functional theory (B3LYP/Def2-TZVPP) based methods and NBO interpretation were used to investigate the impacts of the stereoelectronic effects and electrostatic and steric interactions on the conformational properties of halocarbonyl isocyanates (halo = F (1), Cl (2), and Br (3)), halothiocarbonyl isocyanates (halo = F (4), Cl (5), and Br (6)), and haloselenocarbonyl isocyanates(halo = F (7), Cl (8), and Br (9)). Both methods showed that the Z-conformations of compounds 1, 4, and 7 are more stable than their corresponding E conformations, but the stability of the E conformations, when compared with the corresponding Z conformations, increases from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9. The NBO analysis showed that the generalized anomeric effect (GAE) is in favor of the Z conformations of compounds 1, 4, and 7. The GAE values calculated (i.e., GAEE–GAEZ) increase from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9. On the other hand, there are none of the same trends between the calculated total dipole moment and the Gibbs free energy difference values between the E and Z conformations (i.e., ΔμE–Z and ΔGE–Z) of compounds 1–3, 4–6, and 7–9. Accordingly, the GAE succeeds in accounting for the increase of the E conformation stability from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9. Therefore, the GAE associated with the electron delocalization, not the total dipole moment changes (i.e., ΔμE–Z), is a reasonable indicator of the total energy difference in compounds 1–3, 4–6, and 7–9. There is a direct correlation between the calculated GAE and Δ[r2–6(E) – r2–6(Z)] parameters. Importantly, there are interesting through-space electron delocalizations (LP2X6→π*C4–O5) that justify the increase of the E conformation stability from compound 1 to compound 3, compound 4 to compound 6, and also from compound 7 to compound 9, when compared with their corresponding Z conformations. The correlations between the GAE, bond orders, total steric exchange energies (TSEE), ΔGZ–E, ΔμE–Z, structural parameters, and conformational behaviors of compounds 1–9 were investigated.
Bonding topology, hydrogen bond strength, and vibrational chemical shifts on hetero-ring hydrogen-bonded complexes — Theoretical insights revisited
Authors: Oliveira Boaz G. , Araújo Regiane C. M. U.
Published: March 2012

This work presents a theoretical study about the interaction strength of the hydrogen-bonded complexes C2H4O···HF, C3H6O···HF, C2H4O···HCF3, and C3H6O···HCF3 at the B3LYP/6–311++G(d,p) level. The structures, hydrogen bond energies, charge transfers, and dipole moments of these complexes were analyzed in accordance with routine spectroscopy events, such as the red- and blue-shifts on the stretch frequencies of the proton donors (HF and HCF3). The ChelpG atomic charges were used to quantify the charge-transfer fluxes from electron donor (O) towards to acceptors (HF or HCF3). Moreover, the topological calculations on the basis of the quantum theory of atoms in molecules (QTAIM) approach were also used to unveil the hydrogen bond strength (O···H), mainly in the determination of their electronic densities and Laplacian shapes.
In vitro conservation of American elm (Ulmus americana): potential role of auxin metabolism in sustained plant proliferation
Authors: Shukla Mukund R. , Jones A. Maxwell P. , Sullivan J. Alan , Liu Chunzhao , Gosling Susan , Saxena Praveen K.
Published: March 2012

An efficient procedure for the conservation of mature American elm ( Ulmus americana L.) trees that have survived the epidemics of Dutch elm disease and are potential sources of disease resistance is reported. The model utilizes in vitro proliferation of fresh and dormant buds from mature trees for cloning nearly 100 year old American elm trees. The key factors that influenced sustained growth and multiplication included optimization of culture process and auxin metabolism in the source tissue. Blocking the action of endogenous auxins through the addition of antiauxin in the proliferation medium was crucial for high multiplication rate and optimum shoot development. Addition of antiauxin also mitigated the decline in productivity observed with multiple subcultures, which will enable long-term conservation of selected germplasm. The most effective medium for long-term proliferation contained 5.0 µmol/L p-chlorophenoxyisobutyric acid with 2.2 µmol/L benzylaminopurine and 0.29 µmol/L gibberellic acid. Medium with 2.5 µmol/L indole-3-butyric acid was the best for rooting microshoots (89%). Rooted plantlets were readily acclimatized to the greenhouse environment with a 90% survival rate. The strategy developed for American elm will aid in increasing multiplication of resistant clones, facilitate long-term conservation of elite genotypes, and also provide an approach to improve conservation of other endangered tree species.
Impacts of pine species, stump removal, cultivation, and fertilization on soil properties half a century after planting
Authors: Butnor J.R. , Johnsen K.H. , Sanchez F.G. , Nelson C.D.
Published: March 2012

To better understand the long-term effects of species selection and forest management practices on soil quality and soil C retention, we analyzed soil samples from an experimental planting of loblolly ( Pinus taeda L.), longleaf ( Pinus palustris Mill.), and slash ( Pinus elliottii Engelm.) pines under different management intensities in Mississippi. The treatments included stump removal and cultivation (CULT), a one-time application of fertilizer combined with stump removal and cultivation (CULT+F), and a control (CON). After 49 years, pine species had no significant effect on any soil physical or chemical parameter examined, despite species differences in basal area. CULT exhibited significantly higher soil bulk density and lower soil C and soil N than CON and CULT+F in the upper 10 cm of soil. Stump removal is not a common practice in southern pine silviculture today; however, as demand for bioenergy fuels or feedstocks increases, more complete biomass utilization will be considered. Residual stumps play an important role in soil nutrient and C retention in pine plantations. Our results show that stump removal can lead to reduced soil C (–21%) and soil N (–35%) compared with controls, although it is possible to mitigate nutrient losses on poor sites with fertilization.
Responses of northern red oak seedlings to lime and deer exclosure fencing in Pennsylvania
Authors: Long Robert P. , Brose Patrick H. , Horsley Stephen B.
Published: March 2012

In Pennsylvania, two hypotheses compete to explain the chronic oak ( Quercus spp.) regeneration problem: excessive deer browsing and soil cation depletion. We tested these hypotheses by evaluating the effect of forest liming and deer exclosure fencing on northern red oak ( Quercus rubra L.) seedling growth and nutrition in five oak shelterwood stands in Pennsylvania over 6 years. In each stand, four planting plots were located inside a 2.4 m high woven wire fence and another four were established outside the fence. About 225 northern red oak acorns were planted in each plot in spring 2004. Dolomitic limestone was applied to randomly selected plots at rates of 0, 4.5, 9.0, and 13.5 Mg·ha–1during May 2004. There were no statistically significant (P ≤ 0.05) growth responses to lime applications. The only significant growth responses resulted from the fence versus no-fence treatment. A significant (P < 0.003) fence × year interaction for seedling height and root collar diameter indicates differential impacts of deer browsing. By 2009, seedlings inside fences averaged 32 cm tall, while seedlings outside the fences averaged 17 cm. Similarly, root collar diameter averaged 6.6 mm outside the fences and 9.1 mm inside fences.
Vertical patterns in specific volume increment along stems of dominant jack pine (Pinus banksiana) and black spruce (Picea mariana) after thinning
Authors: Goudiaby Venceslas , Brais Suzanne , Berninger Frank , Schneider Robert
Published: March 2012

Jack pine ( Pinus banksiana Lamb.) and black spruce ( Picea mariana (Mill.) B.S.P.) total stem volume increment and vertical growth distribution after thinning were quantified and related to foliage biomass, foliage density, and growth efficiency (GE) (stem to foliage biomass ratio). Significant positive stem volume increments were observed following thinning for jack pine (3 years after) and black spruce (4 years after). Both species reacted differently in terms of the distribution in specific volume increments (SVI) (annual stem volume increment to cambial surface ratio): (i) for jack pine, an increase in SVI was first observed at the base of the tree, with the increase moving upwards, showing that the taper was likely to increase following thinning and (ii) for black spruce, the vertical distribution of SVI was constant, leading to no modifications in stem taper. For jack pine, total stem volume growth was related to an increase in GE and a greater foliage biomass at midcrown, with foliage density staying constant. For black spruce, however, no changes in GE, foliage biomass, and foliage mass density were observed.
ELECTRONIC, OPTICAL AND MECHANICAL PROPERTIES OF AIIBVI SEMICONDUCTORS
Authors: YADAV DHEERENDRA SINGH , VERMA A. S.
Published: March 2012

The modified dielectric theory of solids is applied to investigate electronic, optical and mechanical properties of A II B VI binary semiconductors ( ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgS, HgSe & HgTe ). The values of homopolar gaps (Eh), heteropolar gaps (Ec) and average energy gaps (Eg) were evaluated for these A II B VI groups of binary semiconductors with Zinc-blende (ZB) structure. The derived values of average energy gap (Eg) were found to be in excellent agreement with the values obtained from the Penn model except ZnO . The electronic polarizability was investigated using Chemla's relation and the values were found to be in a very good agreement with the results obtained from the Clausius–Mossotti relation. The crystal ionicity (fi) was evaluated and the obtained values were compared with the values obtained by different researchers. The evaluated values of crystal ionicity were used to calculate the electronic, optical, mechanical properties such as bulk modulus (B in GPa) cohesive energy or total energy (U in Ryd. electron) and microhardness (H in GPa) of these compound semiconductors. A good agreement has been found between calculated and experimental data.
EXPERIMENTAL INVESTIGATION OF A TWO-DEGREE-OF-FREEDOM VIBRO-IMPACT SYSTEM
Authors: WEN GUILIN , XU HUIDONG , XIAO LU , XIE XIAOPING , CHEN ZHONG , WU XIN
Published: March 2012

Vibro-impact systems with intermittent contacts are strongly nonlinear. The discontinuity of impact can give rise to rich nonlinear dynamic behaviors and bring forth challenges in the modeling and analysis of this type of nonsmooth systems. The dynamical behavior of a two-degree-of-freedom vibro-impact system is investigated experimentally in this paper. The experimental apparatus is composed of two spring-linked oscillators moving on a lead rail. One of the two oscillators connected to an excitation system intermittently impacts with a spherical obstacle fixed on the thick steel wall. With different gap sizes between the impacting oscillator and the obstacle, the dynamical behaviors are investigated by changing the excitation frequencies. The experimental results show periodic, grazing and chaotic dynamical behaviors of the vibro-impact system.
BIFURCATION CONTROL OF A PARAMETRIC PENDULUM
Authors: DE PAULA ALINE S. , SAVI MARCELO A. , WIERCIGROCH MARIAN , PAVLOVSKAIA EKATERINA
Published: March 2012

In this paper, we apply chaos control methods to modify bifurcations in a parametric pendulum-shaker system. Specifically, the extended time-delayed feedback control method is employed to maintain stable rotational solutions of the system avoiding period doubling bifurcation and bifurcation to chaos. First, the classical chaos control is realized, where some unstable periodic orbits embedded in chaotic attractor are stabilized. Then period doubling bifurcation is prevented in order to extend the frequency range where a period-1 rotating orbit is observed. Finally, bifurcation to chaos is avoided and a stable rotating solution is obtained. In all cases, the continuous method is used for successive control. The bifurcation control method proposed here allows the system to maintain the desired rotational solutions over an extended range of excitation frequency and amplitude.
A SIMPLE YET COMPLEX ONE-PARAMETER FAMILY OF GENERALIZED LORENZ-LIKE SYSTEMS
Authors: WANG XIONG , CHEN JUAN , LU JUN-AN , CHEN GUANRONG
Published: March 2012

This paper reports the finding of a simple one-parameter family of three-dimensional quadratic autonomous chaotic systems. By tuning the only parameter, this system can continuously generate a variety of cascading Lorenz-like attractors, which appears to be richer than the unified chaotic system that contains the Lorenz and the Chen systems as its two extremes. Although this new family of chaotic systems has very rich and complex dynamics, it has a very simple algebraic structure with only two quadratic terms (same as the Lorenz and the Chen systems) and all nonzero coefficients in the linear part being -1 except one -0.1 (thus, simpler than the Lorenz and Chen systems). Surprisingly, although this new system belongs to the Lorenz-type of systems in the classification of the generalized Lorenz canonical form, it can generate not only Lorenz-like attractors but also Chen-like attractors. This suggests that there may exist some other unknown yet more essential algebraic characteristics for describing general three-dimensional quadratic autonomous chaotic systems.
NOISY CHAOS IN A QUASI-INTEGRABLE HAMILTONIAN SYSTEM WITH TWO DOF UNDER HARMONIC AND BOUNDED NOISE EXCITATIONS
Authors: GAN C. B. , WANG Y. H. , YANG S. X. , LEI H.
Published: March 2012

This paper presents an extended form of the high-dimensional Melnikov method for stochastically quasi-integrable Hamiltonian systems. A quasi-integrable Hamiltonian system with two degree-of-freedom (DOF) is employed to illustrate this extended approach, from which the stochastic Melnikov process is derived in detail when the harmonic and the bounded noise excitations are imposed on the system, and the mean-square criterion on the onset of chaos is then presented. It is shown that the threshold of the onset of chaos can be adjusted by changing the deterministic intensity of bounded noise, and one can find the range of the parameter related to the bandwidth of the bounded noise excitation where the chaotic motion can arise more readily by investigating the changes of the threshold region. Furthermore, some parameters are chosen to simulate the sample responses of the system according to the mean-square criterion from the extended stochastic Melnikov method, and the largest Lyapunov exponents are then calculated to identify these sample responses.
GENERATION AND IMPLEMENTATION OF HYPERCHAOTIC CHUA SYSTEM VIA STATE FEEDBACK CONTROL
Authors: XI HUILING , YU SIMIN , ZHANG CHAOXIA , SUN YOULIN
Published: March 2012

In this paper, a 4D hyperchaotic Chua system both with piecewise-linear nonlinearity and with smooth and piecewise smooth cubic nonlinearity is introduced, based on state feedback control. Dynamical behaviors of this hyperchaotic system are further investigated, including Lyapunov exponents spectrum, bifurcation diagram and solution of state equations. Theoretical analysis and numerical results show that this system can generate multiscroll hyperchaotic attractors. In addition, a circuit is designed for 4D hyperchaotic Chua system such that the double-scroll and 3-scroll hyperchaotic attractors can be physically obtained, demonstrating the effectiveness of the proposed simulation-based techniques.
Cognitive Bias Modification Approaches to Anxiety
Authors: MacLeod Colin , Mathews Andrew
Published: March 2012

Clinical anxiety disorders and elevated levels of anxiety vulnerability are characterized by cognitive biases, and this processing selectivity has been implicated in theoretical accounts of these conditions. We review research that has sought to evaluate the causal contributions such biases make to anxiety dysfunction and to therapeutically alleviate anxiety using cognitive-bias modification (CBM) procedures. After considering the purpose and nature of CBM methodologies, we show that variants designed to modify selective attention (CBM-A) or interpretation (CBM-I) have proven capable of reducing anxiety vulnerability and ameliorating dysfunctional anxiety. In addition to supporting the causal role of cognitive bias in anxiety vulnerability and dysfunction and illuminating the mechanisms that underpin such bias, the findings suggest that CBM procedures may have therapeutic promise within clinical settings. We discuss key issues within this burgeoning field of research and suggest future directions CBM research should take to maximize its theoretical and applied value.
Validity of triple- and dual-tracer techniques to estimate glucose appearance
Authors: Haidar A. , Elleri D. , Allen J. M. , Harris J. , Kumareswaran K. , Nodale M. , Acerini C. L. , Wilinska M. E. , Jackson N. , Umpleby A. M. , Evans M. L. , Dunger D. B. , Hovorka R.
Published: March 2012

The triple-tracer (TT) dilution technique has been proposed to be the gold standard method to measure postprandial glucose appearance. However, validation against an independent standard has been missing. We addressed this issue and also validated the simpler dual-tracer (DT) technique. Sixteen young subjects with type 1 diabetes (age 19.5 ± 3.8 yr, BMI 23.4 ± 1.5 kg/m2, HbA1c8.7 ± 1.7%, diabetes duration 9.0 ± 6.9 yr, total daily insulin 0.9 ± 0.2 U·kg−1·day−1, mean ± SD) received a variable intravenous 20% dextrose infusion enriched with [U-13C]glucose over 8 h to achieve postprandial-resembling glucose excursions while intravenous insulin was administered to achieve postprandial-resembling levels of plasma insulin. Primed [6,6-2H2]glucose was infused in a manner that mimicked the expected endogenous glucose production and [U-13C; 1,2,3,4,5,6,6-2H7]glucose was infused in a manner that mimicked the expected glucose appearance from a standard meal. Plasma glucose enrichment was measured by gas chromatography-mass spectrometry. The intravenous dextrose infusion served as an independent standard and was reconstructed using the TT and DT techniques with the two-compartment Radziuk/Mari model and an advanced stochastic computational method. The difference between the infused and reconstructed dextrose profile was similar for the two methods (root mean square error 6.6 ± 1.9 vs. 8.0 ± 3.5 μmol·kg−1·min−1, TT vs. DT, P = NS, paired t-test). The TT technique was more accurate in recovering the overall dextrose infusion (100 ± 9 and 92 ± 12%; P = 0.02). The root mean square error associated with the mean dextrose infusion profile was 2.5 and 3.3 μmol·kg−1·min−1for the TT and DT techniques, respectively. We conclude that the TT and DT techniques combined with the advanced computational method can measure accurately exogenous glucose appearance. The TT technique tends to outperform slightly the DT technique, but the latter benefits from reduced experimental and computational complexity.
Activity of the same motor cortex neurons during repeated experience with perturbed movement dynamics
Authors: Richardson Andrew G. , Borghi Tommaso , Bizzi Emilio
Published: March 2012

Neurons in the primary motor cortex (M1) have been shown to have persistent, memory-like activity following adaptation to altered movement dynamics. However, the techniques used to study these memory traces limited recordings to only single sessions lasting no more than a few hours. Here, chronically implanted microelectrode arrays were used to study the long-term neuronal responses to repeated experience with perturbing, velocity-dependent force fields. Force-field–related neuronal activity within each session was similar to that found previously. That is, the directional tuning curves of the M1 neurons shifted in a manner appropriate to compensate for the forces. Next, the across-session behavior was examined. Long-term learning was evident in the performance improvements across multiple force-field sessions. Correlated with this change, the neuronal population had smaller within-session spike rate changes as experience with the force field increased. The smaller within-session changes were a result of persistent across-session shifts in directional tuning. The results extend the observation of memory traces of newly learned dynamics and provide further evidence for the role of M1 in early motor memory formation.
Human brain cortical correlates of short-latency afferent inhibition: a combined EEG–TMS study
Authors: Ferreri Florinda , Ponzo David , Hukkanen Taina , Mervaala Esa , Könönen Mervi , Pasqualetti Patrizio , Vecchio Fabrizio , Rossini Paolo Maria , Määttä Sara
Published: March 2012

When linking in time electrical stimulation of the peripheral nerve with transcranial magnetic stimulation (TMS), the excitability of the motor cortex can be modulated to evoke clear inhibition, as reflected by the amplitude decrement in the motor-evoked potentials (MEPs). This specific property, designated short-latency afferent inhibition (SAI), occurs when the nerve–TMS interstimulus interval (ISI) is approximately 25 ms and is considered to be a corticothalamic phenomenon. The aim of the present study was to use the electroencephalographic (EEG) responses to navigated-TMS coregistration to better characterize the neuronal circuits underlying SAI. The present experimental set included magnetic resonance imaging (MRI)–navigated TMS and 60-channel TMS-compatible EEG devices. TMS-evoked EEG responses and MEPs were analyzed in eight healthy volunteers; ISIs between median nerve and cortical stimulation were determined relative to the latency of the individual N20 component of the somatosensory-evoked potential (SEP) obtained after stimulation of the median nerve. ISIs from the latency of the N20 plus 3 ms and N20 plus 10 ms were investigated. In all experimental conditions, TMS-evoked EEG responses were characterized by a sequence of negative deflections peaking at approximately 7, 44, and 100 ms alternating with positive peaks at approximately 30, 60, and 180 ms post-TMS. Moreover, ISI N20+3 ms modulated both EEG-evoked activity and MEPs. In particular, it inhibited MEP amplitudes, attenuated cortical P60 and N100 responses, and induced motor cortex beta rhythm selective decrement of phase locking. The findings of the present experiment suggest the cortical origin of SAI that could result from the cortico–cortical activation of GABAergic-mediated inhibition onto the corticospinal neurons modulated by cholinergic activation able to reducing intralaminar inhibition and promoting intracolumnar inhibition.