bluuebunny/crossref_metadata_2025 huggingface dataset:
Isotopic insights into smoothening of abandoned fan surfaces, Southern California
Authors: Matmon Ari , Nichols Kyle , Finkel Robert
Published: April 2006

Cosmogenic nuclide concentrations measured on abandoned fan surfaces along the Mojave section of the San Andreas Fault suggest that sediment is generated, transported, and removed from the fans on the order of 30–40 kyr. We measured in situ produced cosmogenic 10Be, and in some cases 26Al, in boulders (n = 15), surface sediment (n = 15), and one depth profile (n = 9). Nuclide concentrations in surface sediments and boulders underestimate fan ages, suggesting that 10Be accumulation is largely controlled by the geomorphic processes that operate on the surfaces of the fans and not by their ages.

Field observations, grain-size distribution, and cosmogenic nuclide data suggest that over time, boulders weather into grus and the bar sediments diffuse into the adjacent swales. As fans grow older the relief between bars and swales decreases, the sediment transport rate from bars to swales decreases, and the surface processes that erode the fan become uniform over the entire fan surface. The nuclide data therefore suggest that, over time, the difference in 10Be concentration between bars and swales increases to a maximum until the topographic relief between bars and swales is minimized, resulting in a common surface lowering rate and common 10Be concentrations across the fan. During this phase, the entire fan is lowered homogeneously at a rate of 10–15 mm kyr−1.
Retinal bipolar cell types differ in their inventory of ion channels
Authors: IVANOVA ELENA , MÜLLER FRANK
Published: April 2006

Bipolar cells were recorded in rat retinal slices to study the distribution of hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels. Patch-clamp whole cell measurements were combined with intracellular filling and recorded cells were morphologically identified. HCN channel isoforms HCN1-4 are differentially expressed in bipolar cells. Each bipolar cell type has a characteristic inventory of HCN channels. The combination of HCN channel currents and other voltage-gated currents can be used as a kind of “finger print” to electrophysiologically identify and classify bipolar cell types. Using this approach of combined electrophysiological and morphological classification we could identify a new ON-cone bipolar cell type.
Sensitivity to visual motion in amblyopic macaque monkeys
Authors: KIORPES LYNNE , TANG CHAO , MOVSHON J. ANTHONY
Published: April 2006

Amblyopia is usually considered to be a deficit in spatial vision. But there is evidence that amblyopes may also suffer specific deficits in motion sensitivity as opposed to losses that can be explained by the known deficits in spatial vision. We measured sensitivity to visual motion in random dot displays for strabismic and anisometropic amblyopic monkeys. We used a wide range of spatial and temporal offsets and compared the performance of the fellow and amblyopic eye for each monkey. The amblyopes were severely impaired at detecting motion at fine spatial and long temporal offsets, corresponding to fine spatial scale and slow speeds. This impairment was also evident for the untreated fellow eyes of strabismic but not anisometropic amblyopes. Motion sensitivity functions for amblyopic eyes were shifted toward large spatial scales for amblyopic compared to fellow eyes, to a degree that was correlated with the shift in scale of the spatial contrast sensitivity function. Amblyopic losses in motion sensitivity, however, were not correlated with losses in spatial contrast sensitivity. This, combined with the specific impairment for detecting long temporal offsets, reveals a deficit in spatiotemporal integration in amblyopia which cannot be explained by the lower spatial resolution of amblyopic vision.
Chromatic VEP assessment of human macular pigment: Comparison with minimum motion and minimum flicker profiles
Authors: ROBSON A.G. , HOLDER G.E. , MORELAND J.D. , KULIKOWSKI J.J.
Published: April 2006

To assess the effects of macular pigment optical density (MPOD) on isoluminant stimuli and to quantify MPOD electrophysiologically, MPOD distribution profiles were obtained in normal subjects using minimum motion and minimum flicker photometry. Isoluminance of VEP stimuli was determined using minimum flicker and tritan confusion lines were determined using a minimum distinct border criterion. Onset–offset and reversal VEPs to isoluminant red/green, blue/green, and subject-specific tritan gratings of different diameters were recorded from the same 14 subjects tested psychophysically. VEPs were additionally recorded to annular gratings. Chromatic VEP selectivity was assessed by Fourier analysis and as an index; onset negativity/(onset negativity + onset positivity). Peak MPOD varied between 0.2–0.8. Chromatic onset VEPs to all isoluminant 3-deg fields were predominantly negative. Larger blue/green and tritan stimuli elicited VEPs with additional positive, achromatic components; for 9-deg gratings, peak MPOD showed negative correlation with the power of the VEP fundamental (r= −0.70) and with the selectivity index (r= −0.83). Annular gratings elicited chromatic-specific B/G VEPs but only when isoluminance was determined for the annulus. Chromatic selectivity loss in VEPs to large B/G or Tritan gratings can be used to estimate subject-specific MPOD. An important implication is that isoluminant Tritan stimuli with short-wavelength components must be restricted in size in order to optimize koniocellular selectivity.
Algorithms to Assess non-Heme Iron Bioavailability
Authors: Reddy Manju B.
Published: April 2006

While sufficient information exists on the effect of individual factors on iron absorption, their net effect in a mixed meal is less well characterized, being dependent on the combination and quantity of the factors present in the meal. Over a period of more than 25 years, several models have been developed to estimate non-heme iron bioavailability, either to assess iron absorption from a meal or iron sufficiency in populations. Initially, a model was developed to calculate iron absorption in individuals with varying iron status that included only enhancers. This model was useful in classifying the diets but has limited value for accurale assessment. Later models were modified and improved by including inhibitors in the calculations. However, some included either phytate or tea but not in combination. The models that included all the factors in calculations assumed their effect was independent and additive rather than interactive, which is an important issue in addressing iron bioavailability. Although some of the models correlated estimated bioavailability with iron status of the population, the accuracy of the estimations is of concern due to lack of quantitative measurements of bioavailability modifiers, inability to consider interactive effects, and the use of non-iron status measurements. Recent research has led to the development of refined models to assess iron bioavailability of complex meals by comprehensively taking into consideration the interactive effect among enhancers and inhibitors. However, the models are based on single-meal studies and their application to whole diets at a population level is not clear. Accurate measurements of dietary factors and independent validation are needed before using these models. To date, no single model is applicable to all diets and additional studies are needed to develop new models to predict bioavailability of whole diets accurately, in addition to addressing dietary adequacy in all populations.
The Precision of in vitro Methods and Algorithms for Predicting the Bioavailability of Dietary Iron
Authors: Lynch Sean
Published: April 2006

Three factors determine how much iron will be absorbed from a meal. They are the physiological mechanisms that regulate uptake by and transfer through the enterocytes in the upper small intestine, the quantity of iron in the meal, and its availability to the cellular iron transporters. Established methods exist for predicting the effect of physiological regulation and for measuring or estimating meal iron content. Three approaches to estimating bioavailability have been advocated. Two are in vitro screening procedures: measurement of dialyzable iron and Caco-2 cell uptake, both carried out after in vitro simulated gastric and pancreatic digestion. The third is the use of algorithms based on the predicted effects of specific meal components on absorption derived from isotopic studies in human volunteers. The in vitro procedures have been very useful for identifying and characterizing factors that affect non-heme iron absorption, but direct comparisons between absorption predicted from the in vitro tests and measurements in human volunteers have only been made in a limited number of published studies. The available data indicate that dialysis and Caco-2 cell uptake are useful for ranking meals and single food items in terms of predicted iron bioavailability, but may not reflect the magnitudes of the effects of factors that influence absorption accurately. Algorithms based on estimates of the amounts of heme iron and of enhancers and inhibitors of non-heme iron absorption in foods make it possible to classify meals or diets as being of high, medium, or low bioavailability. The precision with which meal iron bioavailability can be predicted in a population, for which a specific algorithm has been developed, is improved by measuring the content of the most important enhancers and inhibitors. However, the accuracy of such predictions appears to be much lower when the algorithm is applied to meals eaten by different populations.
Die Bedeutung des Arbeitsumfelds für die Veränderung der Transfermotivation
Authors: Leitl Julia , Zempel-Dohmen Jeannette
Published: April 2006

Zusammenfassung. Der vorliegende Beitrag setzt sich mit der Veränderung der Transfermotivation in den ersten Monaten nach einer Trainingsmaßnahme auseinander. Es wird angenommen, dass die anfängliche Transfermotivation abnimmt, wobei unter günstigen Bedingungen (z. B. hohe soziale Unterstützung durch den Vorgesetzten) dieses Absinken schwächer ausfällt als unter ungünstigen Bedingungen (z. B. geringe soziale Unterstützung durch den Vorgesetzten). Um die Bedeutung der wahrgenommenen Günstigkeit des Arbeitsumfelds für die Aufrechterhaltung der Transfermotivation zu ermitteln, wurden 163 Teilnehmer von Führungs-, Sozialkompetenz- und Verkaufstrainings in einer Längsschnittstudie befragt. Es wurde geprüft, ob sich die Transfermotivation während der Zeit des Transfers veränderte und ob diese Veränderung von der Günstigkeit der Bedingungen des Arbeitsumfelds beeinflusst wurde. Die Ergebnisse zeigten, dass sich die Transfermotivation in den ersten Monaten nach einer Trainingsmaßnahme reduzierte. Im Weiteren wurde festgestellt, dass das Verhalten des Vorgesetzten für die Veränderung der Transfermotivation eine entscheidende Rolle spielte. Bei hoher sozialer Unterstützung durch den Vorgesetzten war ein geringeres Absinken der Transfermotivation in den ersten Monaten nach einer Trainingsmaßnahme zu verzeichnen als bei niedriger sozialer Unterstützung. Bei anderen Arbeitsumfeldvariablen (soziale Unterstützung durch Kollegen, Zeitdruck und Handlungsspielraum) konnte kein signifikanter Einfluss auf die Veränderung der Transfermotivation in den ersten Monaten nach einem Training nachgewiesen werden.
A spatially distributed model for the dynamic prediction of sediment erosion and transport in mountainous forested watersheds
Authors: Doten Colleen O. , Bowling Laura C. , Lanini Jordan S. , Maurer Edwin P. , Lettenmaier Dennis P.
Published: April 2006

Erosion and sediment transport in a temperate forested watershed are predicted with a new sediment model that represents the main sources of sediment generation in forested environments (mass wasting, hillslope erosion, and road surface erosion) within the distributed hydrology‐soil‐vegetation model (DHSVM) environment. The model produces slope failures on the basis of a factor‐of‐safety analysis with the infinite slope model through use of stochastically generated soil and vegetation parameters. Failed material is routed downslope with a rule‐based scheme that determines sediment delivery to streams. Sediment from hillslopes and road surfaces is also transported to the channel network. A simple channel routing scheme is implemented to predict basin sediment yield. We demonstrate through an initial application of this model to the Rainy Creek catchment, a tributary of the Wenatchee River, which drains the east slopes of the Cascade Mountains, that the model produces plausible sediment yield and ratios of landsliding and surface erosion when compared to published rates for similar catchments in the Pacific Northwest. A road removal scenario and a basin‐wide fire scenario are both evaluated with the model.
Post‐processing removal of correlated errors in GRACE data
Authors: Swenson Sean , Wahr John
Published: April 2006

Gravity fields produced by the Gravity Recovery and Climate Experiment (GRACE) satellite mission require smoothing to reduce the effects of errors present in short wavelength components. As the smoothing radius decreases, these errors manifest themselves in maps of surface mass variability as long, linear features generally oriented north to south (i.e., stripes). The presence of stripes implies correlations in the gravity field coefficients. Here we examine the spectral signature of these correlated errors, and present a method to remove them. Finally, we apply the filter to a model of surface‐mass variability to show that the filter has relatively little degradation of the underlying geophysical signals we seek to recover.
Analysis and simulation of chemical explosions in nonspherical cavities in granite
Authors: Stevens Jeffry L. , Gibbons Steven , Rimer Norton , Xu Heming , Lindholm Conrad , Ringdal Frode , Kvaerna Tormod , Murphy John R.
Published: April 2006

We analyze data from 15 decoupled chemical explosions conducted from 1986 to 2002 in Älvdalen, Sweden, recorded on regional seismic stations NORES, HFS, and NORSAR. The explosions were conducted in three approximately rectangular granite chambers at a depth of 100 m in chambers with volumes of 200, 300, and 1000 m3 and yields ranging from 500 to 10,000 kg. The smallest explosions in the largest chamber are fully decoupled, while the other explosions are partially coupled, overdriven by up to a factor of 25. The data show that decoupling remains fairly constant for overdrive up to about a factor of 10 then decreases rapidly at higher yields. Several 1000 kg explosions were conducted in the two smaller chambers. These events did not appear in seismic bulletins; however, we were able to identify the waveform and to estimate the origin time using a waveform correlation procedure. For the more recent explosions, near‐field data were recorded on pressure gauges in the chamber and adjacent tunnel and on velocity gauges in boreholes at several locations near the chamber. We have modeled these data using three‐dimensional finite difference calculations. The calculations show enhanced signals in the direction along the small axis of the chamber and reduced signals near the long end of the tunnel. Although we do not have free‐field data from all directions, the data for the available locations are consistent with these calculations.
A constrained robust least squares approach for contaminant release history identification
Authors: Sun Alexander Y. , Painter Scott L. , Wittmeyer Gordon W.
Published: April 2006

Contaminant source identification is an important type of inverse problem in groundwater modeling and is subject to both data and model uncertainty. Model uncertainty was rarely considered in the previous studies. In this work, a robust framework for solving contaminant source recovery problems is introduced. The contaminant source identification problem is first cast into one of solving uncertain linear equations, where the response matrix is constructed using a superposition technique. The formulation presented here is general and is applicable to any porous media flow and transport solvers. The robust least squares (RLS) estimator, which originated in the field of robust identification, directly accounts for errors arising from model uncertainty and has been shown to significantly reduce the sensitivity of the optimal solution to perturbations in model and data. In this work, a new variant of RLS, the constrained robust least squares (CRLS), is formulated for solving uncertain linear equations. CRLS allows for additional constraints, such as nonnegativity, to be imposed. The performance of CRLS is demonstrated through one‐ and two‐dimensional test problems. When the system is ill‐conditioned and uncertain, it is found that CRLS gave much better performance than its classical counterpart, the nonnegative least squares. The source identification framework developed in this work thus constitutes a reliable tool for recovering source release histories in real applications.
Structures and relative stability of medium-sized silicon clusters. V. Low-lying endohedral fullerenelike clusters Si31–Si40 and Si45
Authors: Yoo Soohaeng , Shao N. , Koehler C. , Fraunhaum T. , Zeng X. C.
Published: April 2006

We have performed unconstrained search for low-lying structures of medium-sized silicon clusters Si31–Si40 and Si45, by means of the minimum-hopping global optimization method coupled with a density-functional based tight-binding model of silicon. Subsequent geometric optimization by using density-functional theory with the PBE, BLYP, and B3LYP functionals was carried out to determine the relative stability of various candidate low-lying silicon clusters obtained from the unconstrained search. The low-lying characteristics of these clusters can be affirmed by comparing the binding energies per atom of these clusters with previously determined lowest-energy clusters(Sin) in the size range of 21⩽n⩽30. In view of the fact that there exist numerous low-lying “endohedral fullerenelike” isomers for each size in the range 30⩽n⩽40, we used the homologue carbon-fullerene cage to classify different families of isomers. This structural classification allows us to focus on generic features of various isomers and to group many apparently different isomers into a single family. In addition, we report a new family of low-lying clusters which have “Y-shaped three-arm” structures. Isomers in this “handmade” family can be energetically competitive as the endohedral fullerene isomers when the total energies are calculated with the BLYP or B3LYP functional.
The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results
Authors: Mallamace F. , Broccio M. , Corsaro C. , Faraone A. , Wanderlingh U. , Liu L. , Mou C.-Y. , Chen S. H.
Published: April 2006

By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature TL=223±2K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190–280K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1∕D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time ⟨τT⟩, as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.
Spin transfer in nanomagnetic devices with perpendicular anisotropy
Authors: Meng Hao , Wang Jian-Ping
Published: April 2006

Spin momentum transfer in a nanomagnetic device with perpendicular magnetic anisotropy for both free and fixed magnetic layers is studied. The perpendicular anisotropy is induced by using CoFe∕Pt multilayer. The magnetoresistive loop shows that the perpendicular switching fields for the free and fixed layers are 170 and 380Oe, respectively, with ΔR∕R=0.47%. Resistance-current scanning clearly shows a full out-of-plane switching of the free layer magnetization under a sweeping current, which fully excludes the effect of switching by the magnetic field generated by the current. The critical current density is around 1.0×108A∕cm2, which could be tuned by changing the CoFe∕Pt multilayer structures.
Time-resolved pump probe of 1.55μm InAs∕InP quantum dots under high resonant excitation
Authors: Cornet C. , Labbé C. , Folliot H. , Caroff P. , Levallois C. , Dehaese O. , Even J. , Le Corre A. , Loualiche S.
Published: April 2006

We have performed time-resolved resonant pump-probe experiment to study the dynamic response of InAs∕InP quantum dot transitions. A 72-stacked InAs∕InP quantum dot layer sample is grown on (311)B substrate. Photoluminescence at high excitation power reveals ground and excited transitions. Carrier radiative lifetimes and differential transmission are determined under strong excitation powers. The variation of measured carrier radiative lifetimes with increasing excitation powers is attributed to the exciton and biexciton lifetimes difference. The implications of such a difference on differential transmission are discussed, and finally exciton and biexciton lifetimes are measured to be about 1720 and 530ps, respectively.
Size-dependent melting behavior of Zn nanowire arrays
Authors: Wang Xue Wei , Fei Guang Tao , Zheng Kang , Jin Zhen , De Zhang Li
Published: April 2006

The melting behavior of Zn nanowires embedded in the holes of porous anodic alumina membrane with different diameters was studied by using the differential scanning calorimetry. The crystalline structure and morphology of Zn nanowire arrays were characterized by x-ray diffraction and transmission electron microscopy. The melting temperature of Zn nanowire arrays shows the strong dependence on nanowire sizes. The melting temperature was curvilinear with the reciprocal of the diameter of nanowires with the change of the diameter, which was discussed in terms of size-dependent heat of fusion change.
Growth of III-nitride photonic structures on large area silicon substrates
Authors: Li J. , Lin J. Y. , Jiang H. X.
Published: April 2006

We report on the growth of high quality aluminum nitride (AlN) and gallium nitride (GaN) epilayers on large area (6in. diameter) silicon (111) substrates by metal organic chemical vapor deposition. We have demonstrated the feasibility of growing crack-free high quality III-nitride photonic structures and devices on 6inch Si substrates through the fabrication of blue light emitting diodes based upon nitride multiple quantum wells with high performance. The demonstration further enhances the prospects for achieving photonic integrated circuits based upon nitride-on-Si material system.
Sleep after spatial learning promotes covert reorganization of brain activity
Authors: Orban Pierre , Rauchs Géraldine , Balteau Evelyne , Degueldre Christian , Luxen André , Maquet Pierre , Peigneux Philippe
Published: April 2006

Sleep promotes the integration of recently acquired spatial memories into cerebral networks for the long term. In this study, we examined how sleep deprivation hinders this consolidation process. Using functional MRI, we mapped regional cerebral activity during place-finding navigation in a virtual town, immediately after learning and 3 days later, in subjects either allowed regular sleep (RS) or totally sleep-deprived (TSD) on the first posttraining night. At immediate and delayed retrieval, place-finding navigation elicited increased brain activity in an extended hippocampo-neocortical network in both RS and TSD subjects. Behavioral performance was equivalent between groups. However, striatal navigation-related activity increased more at delayed retrieval in RS than in TSD subjects. Furthermore, correlations between striatal response and behavioral performance, as well as functional connectivity between the striatum and the hippocampus, were modulated by posttraining sleep. These data suggest that brain activity is restructured during sleep in such a way that navigation in the virtual environment, initially related to a hippocampus-dependent spatial strategy, becomes progressively contingent in part on a response-based strategy mediated by the striatum. Both neural strategies eventually relate to equivalent performance levels, indicating that covert reorganization of brain patterns underlying navigation after sleep is not necessarily accompanied by overt changes in behavior.
A yeast assay probes the interaction between botulinum neurotoxin serotype B and its SNARE substrate
Authors: Fang Hong , Luo Wentian , Henkel Jim , Barbieri Joseph , Green Neil
Published: April 2006

The seven functionally distinct serotypes (A–G) of botulinum neurotoxin (BoNT) are dichains consisting of light chain (LC) with zinc-dependent endoprotease activity connected by one disulfide bond to heavy chain with neuronal-cell translocation and receptor-binding domains. LC-mediated proteolysis of soluble
N
-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and consequent inhibition of synaptic vesicle fusion to the presynaptic membrane of human motor neurons are responsible for flaccid paralysis associated with botulism. LC endoproteolysis is complex, requiring highly extended SNARE sequences at the surface of intracellular membranes and prompting our development of a genetically amenable assay to monitor the interaction between BoNT/LC and its SNARE substrate. Using BoNT serotype B as a model, the assay employs a chimeric SNARE protein where a portion of neuronal synaptobrevin (Sb) is fused to Snc2p, a Sb ortholog required for protein secretion from yeast cells. Regulated expression of serotype B-LC in yeast leads to cleavage of the chimera and a conditional growth defect. To assess utility of this assay for monitoring SNARE protein cleavage, we growth-selected chimeric SNARE mutations that inhibited proteolysis. When these mutations were introduced into Sb and examined for cleavage, substrate residues located near and distal to the cleavage site were important, including residues positioned near the Sb transmembrane domain, an unexplored aspect of BoNT cell intoxication. Additional mutations were positioned in a nine-residue SNARE motif, supporting a previously assigned role for this motif in LC recognition and providing proof of principle for the application of yeast-based technology to study intracellular BoNT/LC endoproteases.
Acute suppression, but not chronic genetic deficiency, of c-
fos
gene expression impairs long-term memory in aversive taste learning
Authors: Yasoshima Yasunobu , Sako Noritaka , Senba Emiko , Yamamoto Takashi
Published: April 2006

Several lines of evidence have indicated that the establishment of long-term memory requires protein synthesis, including the synthesis of immediate-early gene products. Although the anatomical expression patterns of the c-
fos
gene, a transcription factor-encoding immediate-early gene, in conditioned taste aversion (CTA) are well documented, the functional roles of c-
fos
gene expression and Fos-mediated transcription remain to be clarified. Using the antisense oligodeoxynucleotide (AS-ODN) method in rats and gene-targeting knockout techniques in mice (c-
fos
−/−
mice), we examined the roles of c-
fos
gene expression in the acquisition, retrieval, and retention of CTA. Preconditioning microinfusion of AS-ODN directed against c-
fos
mRNA (c-
fos
AS-ODN) into the parabrachial nucleus (PBN) impaired the acquisition, whereas infusion of control ODNs consisting of a randomized or inverted base order had no effect. Microinfusion of c-
fos
AS-ODN into either the amygdala or insular cortex did not impair the acquisition, whereas it attenuated the retention. Retrieval and subsequent retention of an acquired CTA were not disrupted by c-
fos
AS-ODN infusion into the PBN or amygdala. Microinfusion of another AS-ODN directed against
zif
268 (
egr
-1,
krox
-24,
NGFI
-A) mRNA into the PBN or amygdala did not affect the acquisition and retention. The genetic deficiency in c-
fos
−/−
mice caused normal acquisition and retention. The present results suggest that the Fos-mediated gene transcription in the PBN, amygdala, or insular cortex plays critical roles in the acquisition and/or consolidation, but not the retrieval, of long-term taste memory; nevertheless, some other factors could compensate CTA mechanism when Fos-mediated transcription is not available.
Lung dysfunction causes systemic hypoxia in estrogen receptor β knockout (ERβ
−/−
) mice
Authors: Morani Andrea , Barros Rodrigo P. A. , Imamov Otabek , Hultenby Kjell , Arner Anders , Warner Margaret , Gustafsson Jan-Åke
Published: April 2006

Estrogen receptor β (ERβ) is highly expressed in both type I and II pneumocytes as well as bronchiolar epithelial cells. ERα is not detectable in the adult lung. Lungs of adult female ERβ knockout (ERβ
−/−
) mice have already been reported to have fewer alveoli and reduced elastic recoil. In this article, we report that, by 5 months of age, there are large areas of unexpanded alveoli in lungs of both male and female ERβ
−/−
mice. There is increased staining for collagen and, by EM, abnormal clusters of collagen fibers are seen in the alveolar septa of ERβ
−/−
mice. Immunohistochemical analysis and Western blotting with lung membrane fractions of ERβ
−/−
mice revealed down-regulation of caveolin-1, increased expression of membrane type-1 metalloproteinase, matrix metalloproteinase 2 (active form), and tissue inhibitors of metalloproteinases 2. Hypoxia, measured by immunohistochemical analysis for hypoxia-inducible factor 1α and chemical adducts (with Hypoxyprobe), was evident in the heart, ventral prostate, periovarian sac, kidney, liver, and brain of ERβ
−/−
mice under resting conditions. Furthermore, both male and female adult ERβ
−/−
mice were reluctant to run on a treadmill and tissue hypoxia became very pronounced after exercise. We conclude that ERβ is necessary for the maintenance of the extracellular matrix composition in the lung and loss of ERβ leads to abnormal lung structure and systemic hypoxia. Systemic hypoxia may be responsible for the reported left and right heart ventricular hypertrophy and systemic hypertension in ERβ
−/−
mice.
Living conditions and psychosomatic complaints in Swedish schoolchildren
Authors: Östberg Viveca , Alfven Gösta , Hjern Anders
Published: April 2006

Background: The proportion of Swedish schoolchildren that reports psychosomatic complaints has increased during recent decades, parallel to major structural changes in Swedish society. Aim: To investigate the association of psychosomatic complaints in relation to household socio‐economic conditions. Methods: Cross‐sectional study based on data from child supplements linked to nationally representative household surveys in Sweden during 2000–2003, covering a sample of 5390 children aged 10–18 y. Symptom variables were based on child interviews, while data from parental interviews were used to create socio‐economic variables. Results: Girls more often reported headache and recurrent abdominal pain (RAP) than boys, and these differences became more pronounced with age. Economic stress in the household was associated with headache (OR 1.21, p < 0.05), RAP (OR 1.46, p < 0.001) as well as difficulties falling asleep (OR 1.35, p < 0.01), while there were no consistent associations between symptoms and social class or unemployed parents. Children in single‐parent families consistently reported somewhat more symptoms than children in two‐parent families (OR 1.26 for at least two of the three symptoms, p < 0.05).

Conclusion: Economic stress, but not social class, was a significant but moderate risk factor for all three psychosomatic symptoms. It is possible that a growing proportion of families in economic stress has contributed to the parallel increase in reported psychosomatic complaints among Swedish schoolchildren. Further studies are needed to clarify the relation between lack of money, relational strain/support and psychosomatic complaints.
Low‐Intensity Electromagnetic Millimeter Waves for Pain Therapy
Authors: Usichenko Taras I. , Edinger Hardy , Gizhko Vasyl V. , Lehmann Christian , Wendt Michael , Feyerherd Frank
Published: April 2006

Millimeter wave therapy (MWT), a non‐invasive complementary therapeutic technique is claimed to possess analgesic properties. We reviewed the clinical studies describing the pain‐relief effect of MWT. Medline‐based search according to review criteria and evaluation of methodological quality of the retrieved studies was performed. Of 13 studies, 9 of them were randomized controlled trials (RCTs), only three studies yielded more than 3 points on the Oxford scale of methodological quality of RCTs. MWT was reported to be effective in the treatment of headache, arthritic, neuropathic and acute postoperative pain. The rapid onset of pain relief during MWT lasting hours to days after, remote to the site of exposure (acupuncture points), was the most characteristic feature in MWT application for pain relief. The most commonly used parameters of MWT were the MW frequencies between 30 and 70 GHz and power density up to 10 mW cm−2. The promising results from pilot case series studies and small‐size RCTs for analgesic/hypoalgesic effects of MWT should be verified in large‐scale RCTs on the effectiveness of this treatment method.
Genetic association between male attractiveness and female differential allocation
Authors: Head Megan L , Hunt John , Brooks Robert
Published: April 2006

Differential allocation of reproductive effort towards offspring of attractive mates is a form of post-copulatory mate choice. Although differential allocation has been demonstrated in many taxa, its evolutionary implications have received little attention. Theory predicts that mate choice will lead to a positive genetic correlation between female preference and male attractiveness. This prediction has been upheld for pre-copulatory mate choice, but whether such a relationship between male attractiveness and female differential allocation exists has never been tested. Here, we show that both female pre-copulatory mate choice and post-copulatory differential allocation are genetically associated with male attractiveness in house crickets,
Acheta domesticus
. Daughters of attractive males mated sooner and laid more eggs when paired with larger males. These forms of mate choice are strongest in large females, suggesting that costs decrease with increasing female size. The genetic association between attractiveness and differential allocation suggests potential for differential allocation to become exaggerated by coevolutionary runaway processes in an analogous manner to pre-copulatory choice. Sexual selection is thus likely to be stronger than predicted by pre-copulatory choice alone.
The creep of thin beams under small bending moments
Authors: Srivastava V , Jones H , Greenwood G.W
Published: April 2006

When polycrystalline materials deform at elevated temperatures under low applied stresses by the stress directed migration of vacancies, specific features need consideration in the bending of thin beams since a relatively high stress variation may arise across individual planar grain boundaries in addition to the variation that exists between boundaries of differing inclination. The features depend on grain and beam geometry and expressions are derived for their effect on the rate of deflection of cantilevered beams. Experiments were carried out on beams of high purity copper 100 and 250 μm thick. The cantilever profiles supported the theoretical approach and showed creep rates linearly dependent on stress at rates in accord with predictions based on a diffusional creep process. A further indication of this process was the associated strain localization that resulted in fracture of 100 nm thick alumina coatings applied to some of the beams. The analysis shows how relationships change as the beam thickness approaches the grain size and permits an evaluation of the rate of beam deflection under small bending moments in terms of grain and beam dimensions.
On the size of representative volume element for Darcy law in random media
Authors: Du X , Ostoja-Starzewski M
Published: April 2006

Most studies of effective properties of random heterogeneous materials are based on the assumption of the existence of a representative volume element (RVE), without quantitatively specifying its size
L
relative to that of the micro-heterogeneity
d
. In this paper, we study the finite-size scaling trend to RVE of the Darcy law for Stokesian flow in random porous media, without invoking any periodic structure assumptions, but only assuming the microstructure's statistics to be spatially homogeneous and ergodic. By analogy to the existing methodology in thermomechanics of random materials, we first formulate a Hill–Mandel condition for the Darcy flow velocity and pressure gradient fields. This dictates uniform Neumann and Dirichlet boundary conditions, which, with the help of two variational principles, lead to scale-dependent hierarchies on effective (RVE level) permeability. To quantitatively assess the scaling trend towards the RVE, these hierarchies are computed for various porosities of random disc systems, where the disc centres are generated by a planar hard-core Poisson point field. Overall, it turns out that the higher is the density of random discs—or, equivalently, the narrower are the micro-channels in the system—the smaller is the size of RVE pertaining to the Darcy law.
Mechanistic home range models capture spatial patterns and dynamics of coyote territories in Yellowstone
Authors: Moorcroft Paul R , Lewis Mark A , Crabtree Robert L
Published: April 2006

Patterns of space-use by individuals are fundamental to the ecology of animal populations influencing their social organization, mating systems, demography and the spatial distribution of prey and competitors. To date, the principal method used to analyse the underlying determinants of animal home range patterns has been resource selection analysis (RSA), a spatially implicit approach that examines the relative frequencies of animal relocations in relation to landscape attributes. In this analysis, we adopt an alternative approach, using a series of mechanistic home range models to analyse observed patterns of territorial space-use by coyote packs in the heterogeneous landscape of Yellowstone National Park. Unlike RSAs, mechanistic home range models are derived from underlying correlated random walk models of individual movement behaviour, and yield spatially explicit predictions for patterns of space-use by individuals. As we show here, mechanistic home range models can be used to determine the underlying determinants of animal home range patterns, incorporating both movement responses to underlying landscape heterogeneities and the effects of behavioural interactions between individuals. Our analysis indicates that the spatial arrangement of coyote territories in Yellowstone is determined by the spatial distribution of prey resources and an avoidance response to the presence of neighbouring packs. We then show how the fitted mechanistic home range model can be used to correctly predict observed shifts in the patterns of coyote space-use in response to perturbation.
Beetle assemblages from an Australian tropical rainforest show that the canopy and the ground strata contribute equally to biodiversity
Authors: Stork Nigel E , Grimbacher Peter S
Published: April 2006

There remains great uncertainty about how much tropical forest canopies contribute to global species richness estimates and the relative specialization of insect species to vertical zones. To investigate these issues, we conducted a four-year sampling program in lowland tropical rainforest in North Queensland, Australia. Beetles were sampled using a trap that combines Malaise and flight interception trap (FIT) functions. Pairs of this trap, one on the ground and a second suspended 15–20 m above in the canopy were located at five sites, spaced 50 m or more apart. These traps produced 29 986 beetles of 1473 species and 77 families. There were similar numbers of individuals (canopy 14 473; ground 15 513) and species (canopy 1158; ground 895) in each stratum, but significantly more rare species in the canopy (canopy 509; ground 283). Seventy two percent of the species (excluding rare species) were found in both strata. UsingIndVal, we found 24 and 27% of the abundant species (n≥20 individuals) to be specialized to the canopy and the ground strata, respectively, and equivalent analyses at the family level showed figures of 30 and 22%, respectively. These results show that the canopy and the ground strata both provide important contributions to rainforest biodiversity.
The emerging diversity ofRickettsia
Authors: Perlman Steve J , Hunter Martha S , Zchori-Fein Einat
Published: April 2006

The best-known members of the bacterial genusRickettsiaare associates of blood-feeding arthropods that are pathogenic when transmitted to vertebrates. These species include the agents of acute human disease such as typhus and Rocky Mountain spotted fever. However, many otherRickettsiahave been uncovered in recent surveys of bacteria associated with arthropods and other invertebrates; the hosts of these bacteria have no relationship with vertebrates. It is therefore perhaps more appropriate to considerRickettsiaas symbionts that are transmitted vertically in invertebrates, and secondarily as pathogens of vertebrates. In this review, we highlight the emerging diversity ofRickettsiaspecies that are not associated with vertebrate pathogenicity. Phylogenetic analysis suggests multiple transitions between symbionts that are transmitted strictly vertically and those that exhibit mixed (horizontal and vertical) transmission.Rickettsiamay thus be an excellent model system in which to study the evolution of transmission pathways. We also focus on the emergence ofRickettsiaas a diverse reproductive manipulator of arthropods, similar to the closely relatedWolbachia, including strains associated with male-killing, parthenogenesis, and effects on fertility. We emphasize some outstanding questions and potential research directions, and suggest ways in which the study of non-pathogenicRickettsiacan advance our understanding of their disease-causing relatives.
Modelling aspects of cancer dynamics: a review
Authors: Byrne H.M , Alarcon T , Owen M.R , Webb S.D , Maini P.K
Published: April 2006

Cancer is a complex disease in which a variety of factors interact over a wide range of spatial and temporal scales with huge datasets relating to the different scales available. However, these data do not always reveal the mechanisms underpinning the observed phenomena. In this paper, we explain why mathematics is a powerful tool for interpreting such data by presenting case studies that illustrate the types of insight that realistic theoretical models of solid tumour growth may yield. These range from discriminating between competing hypotheses for the formation of collagenous capsules associated with benign tumours to predicting the most likely stimulus for protease production in early breast cancer. We will also illustrate the benefits that may result when experimentalists and theoreticians collaborate by considering a novel anti-cancer therapy.
Children injured following TV tipovers in Israel, 1997–2003
Authors: Sikron F. , Glasser S. , Peleg K.
Published: April 2006

Background  According to the US Consumer Product Safety Commission, about 7000 children, many under age five, are treated annually at emergency rooms for injuries associated with unintentional tipping of television (TV) and furniture. However, the professional literature does not reflect much inquiry regarding this source of risk. In Israel, cases of children injured following TV tipover are reported in newspapers but no studies were conducted in Israel on this issue. The aim of this report is to present data regarding frequency and characteristics of children injured following a falling TV in Israel during recent years, in order to provide more specific information for advising policymakers and raising awareness about this growing danger.

Methods  Data were obtained from the Israeli National Trauma Registry, and included injured children (0–17) hospitalized between 1997 and 2003, because of TV‐related injury.

Demographic information, Injury Severity Score (ISS), injured body region, surgical intervention, admission to the intensive care unit, length of hospital stay, destination at discharge and mortality were analysed.

Results  There were 116 children injured following TV tipover during the years analysed, increasing from nine in 1997 to 27 in 2003. Over half of the children (54.3%) were aged 1–2 years; 57.8% were boys. Three‐quarters of the TV‐related injuries were head and neck injuries; nearly one‐fifth had ISS scores of over 15. The mean was 4.3 (median = 2 days); 15 children (12.9%) required surgery and four children died in the hospital.

Conclusion  The findings reflect the fact that TV tipover is a growing source of danger that can be serious and should be brought to the attention of the public, health professionals and policymakers. Specific, age‐related recommendations should be proposed, such as placing TVs on low and stable surface and not placing the remote controls on the top of the set.
Context‐dependent effects of freshwater mussels on stream benthic communities
Authors: SPOONER DANIEL E. , VAUGHN CARYN C.
Published: April 2006

1. We asked whether unionid mussels influence the distribution and abundance of co‐occurring benthic algae and invertebrates. In a yearlong field enclosure experiment in a south‐central U.S. river, we examined the effects of living mussels versus sham mussels (shells filled with sand) on periphyton and invertebrates in both the surrounding sediment and on mussel shells. We also examined differences between two common unionid species, Actinonaias ligamentina (Lamarck 1819) and Amblema plicata (Say 1817).

2. Organic matter concentrations and invertebrate densities in the sediment surrounding mussels were significantly higher in treatments with live mussels than treatments with sham mussels or sediment alone. Organic matter was significantly higher in the sediment surrounding Actinonaias than that surrounding Amblema. Actinonaias was more active than Amblema and may have increased benthic organic matter through bioturbation.

3. Living mussels increased the abundance of periphyton on shells and the abundance and richness of invertebrates on shells, whereas effects of sham mussels were similar to sediment alone. Differences in the amount of periphyton growing on the shells of the two mussel species reflected differences in mussel activity and shell morphology.

4. Differences between living and sham mussel treatments indicate that biological activities of mussels provide ecosystem services to the benthic community beyond the physical habitat provided by shells alone. In treatments containing live mussels we found significant correlations between organic matter and chlorophyll a concentrations in the sediment, organic matter concentrations and invertebrate abundance in the sediment and the amount of chlorophyll a on the sediment and invertebrate abundance. There were no significant correlations among these response variables in control treatments. Thus, in addition to providing biogenic structure as habitat, mussels likely facilitate benthic invertebrates by altering the availability of resources (algae and organic matter) through nutrient excretion and biodeposition.

5. Effects of mussels on sediment and shell periphyton concentrations, organic matter concentrations and invertebrate abundance, varied seasonally, and were strongest in late summer during periods of low water volume, low flow, and high water temperature.

6. Our study demonstrates that freshwater mussels can strongly influence the co‐occurring benthic community, but that effects of mussels are context‐dependent and may vary among species.