bluuebunny/crossref_metadata_2025 huggingface dataset:
Sample size and variability of fuel weight estimates in natural stands of lodgepole pine
Authors: Delisle Gilles P. , Woodard Paul M. , Titus Stephen J. , Johnson Allen F.
Published: February 2008

This study assessed the variability of sample estimates for downed and dead woody fuel weight in natural lodgepole pine (Pinuscontorta Dougl.) stands using line-intersect sampling procedures. Equilateral triangles (30 m/side) were established at each of 40 sample sites with variable length transects on each side to estimate fuel weights by diameter class. Regardless of the number of sides measured, the standard error for fuels less than 7.0 cm was at most 20% of the mean. Even measuring only one side of the triangle, using a single transect instead of the triangular sample unit, still achieved standard errors less than 20% of the mean. Standard errors for classes greater than 7.0 cm were all greater than 20% of the mean. For these classes, more samples are required to achieve the 20% standard error limit; however, depending on costs, the triangular sample unit may not be the best solution. In this study, intracluster correlations were above 0.7 for the fuel diameter classes greater than 7.0 cm, suggesting that multiple transects at a given sample location contribute little new information. This effect, although less pronounced, was also observed with the smaller diameter classes.
Interference of black cherry by ground flora of the Allegheny uplands
Authors: Drew Allan P.
Published: February 2008

Herbaceous ground flora species of the Northeast are reported to interfere with the growth of seedlings of black cherry (Prunusserotina Ehrh.). To examine this hypothesis, vegetation removal experiments with paired plots were conducted on hayscented fern (Dennstaedtiapunctilobula Michx.) and whorled wood aster (Asteracuminatus Michx.) dominated areas beneath a black cherry overstory following a shelterwood seed cut on the Allegheny uplands of central New York. Complete removal of fern stimulated black cherry germination, height growth, and species diversity increase after two growing seasons. Removal of aster produced the same effect in the first growing season. At the end of 4 years, black cherry growing beneath aster was twice as tall as black cherry of the same age growing beneath fern. Allelochemicals produced by fern, competition for soil nitrogen and forest microsites, and the detrimental effects of reduced light intensity beneath dense fern cover on black cherry physiology are advanced as possible modes of interference of hayscented fern with black cherry seedling growth.
Root systems of older immature hemlock, cedar, and Douglas-fir
Authors: Eis S.
Published: February 2008

not available
A Systematic Review of Acupuncture and Moxibustion Treatment for Chronic Fatigue Syndrome in China
Authors: Wang Tianfang , Zhang Qunhao , Xue Xiaolin , Yeung Albert
Published: February 2008

Studies on the treatment of chronic fatigue syndrome (CFS) with acupuncture and moxibustion in China were reviewed. All studies concluded the treatments were effective, with response rates ranging from 78.95% to 100%. However, the qualities of the studies were generally poor, and none of them used a RCT design. The common acupoints/sites used in the treatment of CFS, which may reflect the collective experience of acupuncturists in China based on Traditional Chinese Medicine theories can be used to evaluate the effectiveness of acupuncture for the treatment of CFS in future studies using more scientifically rigorous study designs.
Interleukin-1α Polymorphism -889C/T Related to Obesity in Korean Taeumin Women
Authors: Song Jeong-Sub , Jeong Hyun-Ja , Kim Su-Jin , Son Mu-Song , Na Ho-Jeong , Song Yong-Sun , Hong Seung-Heon , Kim Hyung-Min , Um Jae-Young
Published: February 2008

Interleukin-1 (IL-1), a cytokine produced predominantly by cells from the macrophage lineage, can affect multiple neuroendocrine and metabolic functions. IL-1α production by cultured peripheral blood mononuclear cells from an obese group was significantly elevated in comparison to a control group. The aim of this study was to investigate whether the IL-1α polymorphism and Sasang constitution, a major branch in Korean traditional medicine, were related to obesity. Genotyping was done in 182 healthy females with a marked variation in body mass index (BMI) by a PCR-restriction fragment length polymorphism assay. The T allele was associated with decreased BMI (p = 0.020). In a subgroup with BMI values ranging from 27 ~ 29 kg/m2, the frequency of the T allele was significantly decreased (p = 0.004, odds ratio, OR = 0.141 compared to a subgroup with a BMI values less than 25 Kg/m2). In addition, in Taeumin female subjects, the frequency of the IL-1α T allele was markedly decreased in a subgroup with BMI values in the range of 27 ~ 29 kg/m2compared to a lean group with BMI values less than 25 kg/m2(p = 0.004, OR = 0.139). In Korean women, an association was found between -889C/T polymorphism in the regulatory region of the IL-1α gene and BMI values. In addition, an association was found among IL-1α polymorphism, obesity, and the Sasang constitution.
Effects of 3-Phenyl-Propenal on the Expression of Toll-Like Receptors and Downstream Signaling Components on Raw264.7 Murine Macrophages
Authors: Zhao Bao-Sheng , Huo Hai-Ru , Ma Yue-Ying , Liu Hong-Bin , Li Lan-Fang , Sui Feng , Li Cang-Hai , Guo Shu-Ying , Jiang Ting-Liang
Published: February 2008

3-phenyl-propenal is one of the principle compounds isolated from Guizhi (Ramulus Cinnamomi), the principal drug in Guizhi-Tang (GZT), a famous traditional Chinese medical formula. The aim of the present study was to investigate the effects of 3-phenyl-propenal on the expression of toll-like receptor 3 (TLR3), TLR4 and the downstream signaling components on Raw264.7 murine microphages. Raw264.7 cells were cultured in RPMI-1640 medium containing LPS (lipopolysaccharide) or poly (I:C) in the presence or absence of 3-phenyl-propenal. After 24-hour incubation, the medium was collected and the amount of TNF-α and IFN-β was measured by ELISA. mRNA expression of TLR3, TLR4, myeloid differentiation factor (MyD88), TRAF-6 (tumor necrosis factor receptor-associated), TRAM (toll-like receptor-associated molecule) and TRIF (TIR domain-containing adaptor inducing IFN-β) were analyzed by real-time PCR with SYBR green dye. Protein expression of TLR3 and TLR4 was analyzed by Western blotting and that of MyD88 and TRAF-6 was analyzed by immunofluorescence assay. The results indicate that LPS increased the expression of TLR4, MyD88, TRAF-6, TRAM and TRIF, but had no influence on TLR3, while poly (I:C) up-regulated the expression of TLR3, MyD88, TRAM and TRIF. 3-phenyl-propenal significantly decreased the expression of LPS-induced TLR4, MyD88, TRAF-6, while possessing no effect on LPS-induced TRAM and TRIF expression in Raw264.7 cells. When cells were stimulated by poly (I:C), 3-phenyl-propenal significantly decreased TLR3 and MyD88 expression. In conclusion, 3-phenyl-propenal blocked the over-expression of TLR3, TLR4, their downstream signaling components MyD88 and TRAF-6, which indicate that it had an antagonistic effect on TLR3 and TLR4.
Arjunic Acid, a Strong Free Radical Scavenger fromTerminalia arjuna
Authors: Sun Fang-Yun , Chen Xiu-Ping , Wang Jin-Hua , Qin Hai-Lin , Yang Su-Rong , Du Guan-Hua
Published: February 2008

This study was designed to investigate the antioxidant and free radical scavenging capacities of arjunic acid, an aglycone obtained from the fruit of medicine Terminalia Fruit. Liver microsomes, mitochondria, and red blood cells (RBCs) were prepared from Wistar rats. The antioxidant capacity was determined by the inhibitory effect on lipid peroxidation, hydrogen peroxide induced RBCs hemolysis, and RBCs autoxidative hemolysis. The free radical scavenging activity was tested by DPPH method and 2′,7′-dichlorodihydrofluoresc in diacetate (DCFH2-DA) assay. Ascorbic acid was chosen as the positive controls. Results showed that arjunic acid was a strong antioxidant and a free radical scavenger, more potent than ascorbic acid, in microsomes lipid peroxidation, DPPH, hydrogen peroxide induced RBCs hemolysis, and (DCFH2-DA) assay (p < 0.05). However, no significant difference was observed in the RBCs autoxidative hemolysis assay (p > 0.05).
STUDY OF THE COMPATIBILITY OF LSND AND WMAP DATA
Authors: CIVITARESE O. , MOSQUERA M. E.
Published: February 2008

The oscillation parameters of an active light-neutrino and a sterile-neutrino scenario, extracted from LSND constraints, are confronted with WMAP and cosmological data. The value of the mixing angle θ is extracted from the primordial abundances of D, 4 He and 7 Li at constant WMAP baryonic density [Formula: see text]. It is found that the best value of sin 22θ, extracted from a θ2 analysis of the combined set of data, depends strongly on the inclusion of the abundance of 7 Li in the sample of primordial abundances.
AN EVAPORATION-BASED MODEL OF THERMAL NEUTRON INDUCED TERNARY FISSION OF PLUTONIUM
Authors: LESTONE J. P.
Published: February 2008

Ternary fission probabilities for thermal neutron induced fission of plutonium are analyzed within the framework of an evaporation-based model where the complexity of time-varying potentials, associated with the neck collapse, are included in a simplistic fashion. If the nuclear temperature at scission and the fission-neck-collapse time are assumed to be ~ 1.2 MeV and ~ 10-22 s, respectively, then calculated relative probabilities of ternary-fission light-charged-particle emission follow the trends seen in the experimental data. The ability of this model to reproduce ternary fission probabilities spanning seven orders of magnitude for a wide range of light-particle charges and masses implies that ternary fission is caused by the coupling of an evaporation-like process with the rapid re-arrangement of the nuclear fluid following scission.
THE RIEMANN HYPOTHESIS IS A CONSEQUENCE OF $\mathcal{CT}$-INVARIANT QUANTUM MECHANICS
Authors: PERELMAN CARLOS CASTRO
Published: February 2008

The Riemann's hypothesis (RH) states that the nontrivial zeros of the Riemann zeta-function are of the form sn = 1/2 + iλn. By constructing a continuous family of scaling-like operators involving the Gauss–Jacobi theta series and by invoking a novel [Formula: see text]-invariant Quantum Mechanics, involving a judicious charge conjugation [Formula: see text] and time reversal [Formula: see text] operation, we show why the Riemann Hypothesis is true. An infinite family of theta series and their Mellin transform leads to the same conclusions.
THE SCALAR WAVE EQUATION IN A NON-COMMUTATIVE SPHERICALLY SYMMETRIC SPACE-TIME
Authors: DI GREZIA ELISABETTA , ESPOSITO GIAMPIERO , MIELE GENNARO
Published: February 2008

Recent work in the literature has studied a version of non-commutative Schwarzschild black holes where the effects of non-commutativity are described by a mass function depending on both the radial variable r and a non-commutativity parameter θ. The present paper studies the asymptotic behavior of solutions of the zero-rest-mass scalar wave equation in such a modified Schwarzschild space-time in a neighborhood of spatial infinity. The analysis is eventually reduced to finding solutions of an inhomogeneous Euler–Poisson–Darboux equation, where the parameter θ affects explicitly the functional form of the source term. Interestingly, for finite values of θ, there is full qualitative agreement with general relativity: the conformal singularity at spacelike infinity reduces in a considerable way the differentiability class of scalar fields at future null infinity. In the physical space-time, this means that the scalar field has an asymptotic behavior with a fall-off going on rather more slowly than in flat space-time.
Balancing Structure and Function at Hippocampal Dendritic Spines
Authors: Bourne Jennifer N , Harris Kristen M
Published: February 2008

Dendritic spines are the primary recipients of excitatory input in the central nervous system. They provide biochemical compartments that locally control the signaling mechanisms at individual synapses. Hippocampal spines show structural plasticity as the basis for the physiological changes in synaptic efficacy that underlie learning and memory. Spine structure is regulated by molecular mechanisms that are fine-tuned and adjusted according to developmental age, level and direction of synaptic activity, specific brain region, and exact behavioral or experimental conditions. Reciprocal changes between the structure and function of spines impact both local and global integration of signals within dendrites. Advances in imaging and computing technologies may provide the resources needed to reconstruct entire neural circuits. Key to this endeavor is having sufficient resolution to determine the extrinsic factors (such as perisynaptic astroglia) and the intrinsic factors (such as core subcellular organelles) that are required to build and maintain synapses.
Place Cells, Grid Cells, and the Brain's Spatial Representation System
Authors: Moser Edvard I. , Kropff Emilio , Moser May-Britt
Published: February 2008

More than three decades of research have demonstrated a role for hippocampal place cells in representation of the spatial environment in the brain. New studies have shown that place cells are part of a broader circuit for dynamic representation of self-location. A key component of this network is the entorhinal grid cells, which, by virtue of their tessellating firing fields, may provide the elements of a path integration–based neural map. Here we review how place cells and grid cells may form the basis for quantitative spatiotemporal representation of places, routes, and associated experiences during behavior and in memory. Because these cell types have some of the most conspicuous behavioral correlates among neurons in nonsensory cortical systems, and because their spatial firing structure reflects computations internally in the system, studies of entorhinal-hippocampal representations may offer considerable insight into general principles of cortical network dynamics.
Is Deliberative Democracy a Falsifiable Theory?
Authors: Mutz Diana C.
Published: February 2008

To further dialogue between theory and research on deliberative democracy, I advocate abandoning tests of deliberative theory per se and instead developing “middle-range” theories that are each important, specifiable, and falsifiable parts of deliberative democratic theory. By replacing vaguely defined entities with more concrete, circumscribed concepts, and by requiring empirically and theoretically grounded hypotheses about specific relationships between those concepts, researchers may come to understand which elements of the deliberative experience are crucial to particular valued outcomes.
Characterization of oxidized low-density lipoprotein-induced hormesis-like effects in osteoblastic cells
Authors: Hamel P. , Abed E. , Brissette L. , Moreau R.
Published: February 2008

Epidemiological studies indicate that patients suffering from atherosclerosis are predisposed to develop osteoporosis. Atherogenic determinants such as oxidized low-density lipoprotein (oxLDL) particles have been shown both to stimulate the proliferation and promote apoptosis of bone-forming osteoblasts. Given such opposite responses, we characterized the oxLDL-induced hormesis-like effects in osteoblasts. Biphasic 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reductive activity responses were induced by oxLDL where low concentrations (10–50 μg/ml) increased and high concentrations (from 150 μg/ml) reduced the MTT activity. Cell proliferation stimulation by oxLDL partially accounted for the increased MTT activity. No alteration of mitochondria mass was noticed, whereas low concentrations of oxLDL induced mitochondria hyperpolarization and increased the cellular levels of reactive oxygen species (ROS). The oxLDL-induced MTT activity was not related to intracellular ROS levels. OxLDL increased NAD(P)H-associated cellular fluorescence and flavoenzyme inhibitor diphenyleneiodonium reduced basal and oxLDL-induced MTT activity, suggesting an enhancement of NAD(P)H-dependent cellular reduction potential. Low concentrations of oxLDL reduced cellular thiol content and increased metallothionein expression, suggesting the induction of compensatory mechanisms for the maintenance of cell redox state. These concentrations of oxLDL reduced osteoblast alkaline phosphatase activity and cell migration. Our results indicate that oxLDL particles cause hormesis-like response with the stimulation of both proliferation and cellular NAD(P)H-dependent reduction potential by low concentrations, whereas high concentrations lead to reduction of MTT activity associated with the cell death. Given the effects of low concentrations of oxLDL on osteoblast functions, oxLDL may contribute to the impairment of bone remodeling equilibrium.
PYY3-36 injection in mice produces an acute anorexigenic effect followed by a delayed orexigenic effect not observed with other anorexigenic gut hormones
Authors: Parkinson James R. C. , Dhillo Waljit S. , Small Caroline J. , Chaudhri Owais B. , Bewick Gavin A. , Pritchard Iain , Moore Stanley , Ghatei Mohammed A. , Bloom Stephen R.
Published: February 2008

Peptide YY (PYY) is secreted postprandially from the endocrine L cells of the gastrointestinal tract. PYY3-36, the major circulating form of the peptide, is thought to reduce food intake in humans and rodents via high-affinity binding to the autoinhibitory neuropeptide Y (NPY) receptor within the arcuate nucleus. We studied the effect of early light-phase injection of PYY3-36 on food intake in mice fasted for 0, 6, 12, 18, 24, and 30 h and show that PYY3-36 produces an acute anorexigenic effect regardless of the duration of fasting. We also show evidence of a delayed orexigenic effect in ad libitum-fed mice injected with PYY3-36 in the early light phase. This delayed orexigenic effect also occurs in mice administered a potent analog of PYY3-36, d-Allo Ile3 PYY3-36, but not following injection of other anorectic agents (glucagon-like-peptide 1, oxyntomodulin, and lithium chloride). Early light-phase injection of PYY3-36 to ad libitum-fed mice resulted in a trend toward increased levels of hypothalamic NPY and agouti-related peptide mRNA and a decrease in proopiomelanocortin mRNA at the beginning of the dark phase. Furthermore, plasma levels of ghrelin were increased significantly, and there was a trend toward decreased plasma PYY3-36 levels at the beginning of the dark phase. These data indicate that PYY3-36 injection results in an acute anorexigenic effect followed by a delayed orexigenic effect.
Weight regain after sustained weight reduction is accompanied by suppressed oxidation of dietary fat and adipocyte hyperplasia
Authors: Jackman Matthew R. , Steig Amy , Higgins Janine A. , Johnson Ginger C. , Fleming-Elder Brooke K. , Bessesen Daniel H. , MacLean Paul S.
Published: February 2008

A dual-tracer approach (dietary14C-palmitate and intraperitoneal3H-H2O) was used to assess the trafficking of dietary fat and net retention of carbon in triglyceride depots during the first 24 h of weight regain. Obesity-prone male Wistar rats were allowed to mature under obesogenic conditions for 16 wk. One group was switched to ad libitum feeding of a low-fat diet for 10 wk (Obese group). The remaining rats were switched to an energy-restricted, low-fat diet for 10 wk that reduced body weight by 14% and were then assessed in energy balance (Reduced group), with free access to the low-fat diet (Relapse-Day1 group), or with a provision that induced a minor imbalance (+10 kcal) equivalent to that observed in obese rats (Gap-Matched group). Fat oxidation remained at a high, steady rate throughout the day in Obese rats, but was suppressed in Reduced, Gap-Matched, and Relapse-Day1 rats though 9, 18, and 24 h, respectively. The same caloric excess in Obese and Gap-Matched rats led to less fat oxidation over the day and greater trafficking of dietary fat to visceral depots in the latter. In addition to trafficking nutrients to storage, Relapse-Day1 rats had more small, presumably new, adipocytes at the end of 24 h. Dietary fat oxidation at 24 h was related to the phosphorylation of skeletal muscle acetyl-CoA carboxylase and fatty acid availability. These observations provide evidence of adaptations in the oxidation and trafficking of dietary fat that extend beyond the energy imbalance, which facilitate rapid, efficient regain during the relapse to obesity.
Osmoregulatory fluid intake but not hypovolemic thirst is intact in mice lacking angiotensin
Authors: McKinley Michael J. , Walker Lesley L. , Alexiou Theodora , Allen Andrew M. , Campbell Duncan J. , Di Nicolantonio Robert , Oldfield Brian J. , Denton Derek A.
Published: February 2008

Water intakes in response to hypertonic, hypovolemic, and dehydrational stimuli were investigated in mice lacking angiotensin II as a result of deletion of the angiotensinogen gene (Agt−/− mice), and in C57BL6 wild-type (WT) mice. Baseline daily water intake in Agt−/− mice was approximately threefold that of WT mice because of a renal developmental disorder of the urinary concentrating mechanisms in Agt−/− mice. Intraperitoneal injection of hypertonic saline (0.4 and 0.8 mol/l NaCl) caused a similar dose-dependent increase in water intake in both Agt−/− and WT mice during the hour following injection. As well, Agt−/− mice drank appropriate volumes of water following water deprivation for 7 h. However, Agt−/− mice did not increase water or 0.3 mol/l NaCl intake in the 8 h following administration of a hypovolemic stimulus (30% polyethylene glycol sc), whereas WT mice increased intakes of both solutions during this time. Osmoregulatory regions of the brain [hypothalamic paraventricular and supraoptic nuclei, median preoptic nucleus, organum vasculosum of the lamina terminalis (OVLT), and subfornical organ] showed an increased number of neurons exhibiting Fos-immunoreactivity in response to intraperitoneal hypertonic NaCl in both Agt−/− mice and WT mice. Polyethylene glycol treatment increased Fos-immunoreactivity in the subfornical organ, OVLT, and supraoptic nuclei in WT mice but only increased Fos-immunoreactivity in the supraoptic nucleus in Agt−/− mice. These data show that brain angiotensin is not essential for the adequate functioning of neural pathways mediating osmoregulatory thirst. However, angiotensin II of either peripheral or central origin is probably necessary for thirst and salt appetite that results from hypovolemia.
Sleep deprivation can inhibit adult hippocampal neurogenesis independent of adrenal stress hormones
Authors: Mueller Anka D. , Pollock Michael S. , Lieblich Stephanie E. , Epp Jonathan R. , Galea Liisa A. M. , Mistlberger Ralph E.
Published: February 2008

Sleep deprivation (SD) can suppress cell proliferation in the hippocampal dentate gyrus of adult male rodents, suggesting that sleep may contribute to hippocampal functions by promoting neurogenesis. However, suppression of cell proliferation in rats by the platform-over-water SD method has been attributed to elevated corticosterone (Cort), a potent inhibitor of cell proliferation and nonspecific correlate of this procedure. We report here results that do not support this conclusion. Intact and adrenalectomized (ADX) male rats were subjected to a 96-h SD using multiple- and single-platform methods. New cells were identified by immunoreactivity for 5-bromo-2′-deoxyuridine (BrdU) or Ki67 and new neurons by immunoreactivity for BrdU and doublecortin. EEG recordings confirmed a 95% deprivation of rapid eye movement (REM) sleep and a 40% decrease of non-REM sleep. Cell proliferation in the dentate gyrus was suppressed by up to 50% in sleep-deprived rats relative to apparatus control or home cage control rats. This effect was also observed in ADX rats receiving continuous low-dose Cort replacement via subcutaneous minipumps but not in ADX rats receiving Cort replacement via drinking water. In these latter rats, Cort intake via water was reduced by 60% during SD; upregulation of cell proliferation by reduced Cort intake may obscure inhibitory effects of sleep loss on cell proliferation. SD had no effect on the percentage of new cells expressing a neuronal phenotype. These results demonstrate that the Cort replacement method is critical for detecting an effect of SD on cell proliferation and support a significant role for sleep in adult neurogenesis.
Mechanical unloading impairs keratinocyte migration and angiogenesis during cutaneous wound healing
Authors: Radek Katherine A. , Baer Lisa A. , Eckhardt Jennifer , DiPietro Luisa A. , Wade Charles E.
Published: February 2008

Although initially thought to improve an individual's ability to heal, mechanical unloading promoted by extended periods of bed rest has emerged as a contributing factor to delayed or aberrant tissue repair. Using a rat hindlimb unloading (HLU) model of hypogravity, we mimicked some aspects of physical inactivity by removing weight-bearing loads from the hindlimbs and producing a systemic cephalic fluid shift. This model simulates bed rest in that the animal undergoes physiological adaptations, resulting in a reduction in exercise capability, increased frequency of orthostatic intolerance, and a reduction in plasma volume. To investigate whether changes associated with prior prolonged bed rest correlate with impaired cutaneous wound healing, we examined wound closure, angiogenesis, and collagen content in day 2 to day 21 wounds from rats exposed to HLU 2 wk before excisional wounding. Wound closure was delayed in day 2 wounds from HLU rats compared with ambulatory controls. Although the levels of proangiogenic growth factors, fibroblast growth factor-2 (FGF-2), and vascular endothelial growth factor (VEGF) were similar between the two groups, wound vascularity was significantly reduced in day 7 wounds from HLU animals. To further examine this disparity, total collagen content was assessed but found to be similar between the two groups. Taken together, these results suggest that keratinocyte and endothelial cell function may be impaired during the wound healing process under periods of prolonged inactivity or bed rest.
HepG2/C3A cells respond to cysteine deprivation by induction of the amino acid deprivation/integrated stress response pathway
Authors: Lee Jeong-In , Dominy John E. , Sikalidis Angelos K. , Hirschberger Lawrence L. , Wang Wei , Stipanuk Martha H.
Published: February 2008

To further define genes that are differentially expressed during cysteine deprivation and to evaluate the roles of amino acid deprivation vs. oxidative stress in the response to cysteine deprivation, we assessed gene expression in human hepatoma cells cultured in complete or cysteine-deficient medium. Overall, C3A cells responded to cysteine deprivation by activation of the eukaryotic initiation factor (eIF)2α kinase-mediated integrated stress response to inhibit global protein synthesis; increased expression of genes containing amino acid response elements ( ASNS, ATF3, CEBPB, SLC7A11, and TRIB3); increased expression of genes for amino acid transporters ( SLC7A11, SLC1A4, and SLC3A2), aminoacyl-tRNA synthetases ( CARS), and, to a limited extent, amino acid metabolism ( ASNS and CTH); increased expression of genes that act to suppress growth ( STC2, FOXO3A, GADD45A, LNK, and INHBE); and increased expression of several enzymes that favor glutathione synthesis and maintenance of protein thiol groups ( GCLC, GCLM, SLC7A11, and TXNRD1). Although GCLC, GCLM, SLC7A11, HMOX, and TXNRD1 were upregulated, most genes known to be upregulated via oxidative stress were not affected by cysteine deprivation. Because most genes known to be upregulated in response to eIF2α phosphorylation and activating transcription factor 4 (ATF4) synthesis were differentially expressed in response to cysteine deprivation, it is likely that many responses to cysteine deprivation are mediated, at least in part, by the general control nondepressible 2 (GCN2)/ATF4-dependent integrated stress response. This conclusion was supported by the observation of similar differential expression of a subset of genes in response to leucine deprivation. A consequence of sulfur amino acid restriction appears to be the upregulation of the cellular capacity to cope with oxidative and chemical stresses via the integrated stress response.
An Innovative Approach to Functionality Testing of Analysers in the Clinical Laboratory
Authors: Stockmann Wolfgang , Engeldinger Werner , Kunst Albert , McGovern Margaret
Published: February 2008

The established protocols for evaluating new analytical systems produce indispensable information with regard to quality characteristics, but in general they fail to analyse the system performance under routine-like conditions. We describe a model which allows the testing of a new analytical system under conditions close to the routine in a controlled and systematic manner by using an appropriate software tool. Performing routine simulation experiments, either reflecting imprecision or method comparison characteristics, gives the user essential information on the overall system performance under real intended-use conditions.
An Influence of Concentration of Polyvinylpyrrolidone on the Morphology of Silver Metal Formed from AgNO3 Aqueous Solution
Authors: Nishino Junichi , Kanno Yoshinori
Published: February 2008

Metal silver rods having a partly regular direction on the substrate are synthesized from the fine copper particles on acrylic plastic plate immersed in 50 μM‐PVP and 0.1 M‐AgNO3 aqueous solution. An increase of PVP concentration in the AgNO3 aqueous solution inhibits the growth of the string‐shaped silver and dendrite‐shaped silver as well as polyol method. The absorbance of the plasmon peak around 410 nm immersed in 0.1 M‐AgNO3 aqueous solution at 25∘C for 24 hours increased with an increase of the PVP concentration.
Neural Processes Supporting Young and Older Adults' Emotional Memories
Authors: Kensinger Elizabeth A. , Schacter Daniel L.
Published: February 2008

Young and older adults are more likely to remember emotional information than neutral information. The present functional magnetic resonance imaging study examined the neural processes supporting young (ages 18–35) and older (ages 62–79) adults' successful encoding of positive, negative, and neutral objects (e.g., a sundae, a grenade, a canoe). The results revealed general preservation of the emotional memory network across the age groups. Both groups recruited the amygdala and the orbito-frontal cortex during the successful encoding of positive and negative information. Both ages also showed valence-specific recruitment: right fusiform activity was greatest during the successful encoding of negative information, whereas left prefrontal and temporal activity was greatest during the successful encoding of positive information. These valence-specific processes are consistent with behavioral evidence that negative information is processed with perceptual detail, whereas positive information is processed at a conceptual or schematic level. The only age differences in emotional memory emerged during the successful encoding of positive items: Older adults showed more activity in the medial prefrontal cortex and along the cingulate gyrus than young adults. Because these regions often are associated with self-referential processing, these results suggest that older adults' mnemonic boost for positive information may stem from an increased tendency to process this information in relation to themselves.
Cholinergic Enhancement Eliminates Modulation of Neural Activity by Task Difficulty in the Prefrontal Cortex during Working Memory
Authors: Furey Maura L. , Ricciardi Emiliano , Schapiro Mark B. , Rapoport Stanley I. , Pietrini Pietro
Published: February 2008

Previously, we demonstrated that enhancing cholinergic activity during a working memory (WM) task improves performance and reduces blood flow in the right anterior middle/superior frontal cortex, an area known to be important for WM. The purpose of this study was to evaluate the interaction between WM task demands and cholinergic enhancement on neural responses in the prefrontal cortex. Regional cerebral blood flow (rCBF) was measured using H2 15O and positron emission tomography, as 10 young healthy volunteers performed a parametrically varied match-to-sample WM for faces task. For each item, a picture of a face was presented, followed by a delay (1, 6, 11, or 16 sec), then by the presentation of two faces. Subjects were instructed to identify which face they previously had seen. For control items, nonsense pictures were presented in the same spatial and temporal manner. All conditions were performed during an intravenous infusion of saline and physostigmine (1 mg/hr). Subjects were blind to the substance being infused. Reaction time increased significantly with WM delay, and physostigmine decreased reaction time across delay conditions. Significant task-related rCBF increases during saline infusion were seen in superior frontal, middle frontal, and inferior frontal regions, and the response magnitudes in the regions increased systematically with task difficulty. In all of these prefrontal regions, physostigmine administration significantly reduced rCBF during task, particularly at longer task delays, so that no correlation between task delay and rCBF was observed. In the ventral visual cortex, physostigmine increased rCBF at longer task delays in medial regions, and decreased rCBF over delay conditions in lateral cortical areas. These results indicate that, during cholinergic potentiation, brain activity in prefrontal regions is not modulated by increases in WM task demands, and lends further support to the hypothesis that cholinergic modulation enhances visual processing, making the task easier to perform, and thus, compensate for the need to recruit prefrontal cortical regions as task demands increase.
On the Magnitude of the Electric Field near Thunderstorm-Associated Clouds
Authors: Merceret Francis J. , Ward Jennifer G. , Mach Douglas M. , Bateman Monte G. , Dye James E.
Published: February 2008

Electric-field measurements made in and near clouds during two airborne field programs are presented. Aircraft equipped with multiple electric-field mills and cloud physics sensors were flown near active convection and into thunderstorm anvil and debris clouds. The magnitude of the electric field was measured as a function of position with respect to the cloud edge to provide an observational basis for modifications to the lightning launch commit criteria (LLCC) used by the U.S. space program. These LLCC are used to reduce the risk that an ascending launch vehicle will trigger a lightning strike that could cause the loss of the mission or vehicle. Even with fields of tens of kV m−1 inside electrically active convective clouds, the fields external to these clouds decay to less than 3 kV m−1 within 15 km of cloud edge. Fields that exceed 3 kV m−1 were not found external to anvil and debris clouds.
Quasi-Steady Katabatic Winds on Slopes in Wide Valleys: Hydraulic Theory and Observations
Authors: Princevac M. , Hunt J. C. R. , Fernando H. J. S.
Published: February 2008

Theoretical and field observational studies on mean velocity and temperature fields of quasi-steady nocturnal downslope (katabatic) flows on sloping surfaces are reported for the case of very wide valleys in the presence of weak synoptic winds. Because of the lateral constraints on the flow, Coriolis effects are considered negligible. The layer-averaged equations of Manins and Sawford were used for the analysis. It is shown that (i) in the absence of significant turbulent entrainment into the current (i.e., at large Richardson numbers Ri = Δh cosα/U2) the downslope flow velocity U is related to the slope length (LH), slope angle (α), and the buoyancy jump between the current and the background atmosphere (Δ) as U = λu(ΔLH sinα)1/2, where λu is a constant and h is the flow depth; (ii) on very long slopes h is proportional to Lh(tanα)1/2; and (iii) under highly stable conditions (i.e., Ri > 1) the katabatic flow exhibits pulsations with period T0 = 2π/N sinα, where N is the buoyancy frequency of the background atmosphere. These predictions are verified principally using observations made during the Vertical Transport and Mixing Experiment (VTMX) conducted in Salt Lake City, Utah, in October 2000. By assuming the flow follows a straight line trajectory to the nearest ridgeline a good agreement was found between the predictions and observations over appropriate Richardson number ranges. For Ri > 1.5, λu ≈ 0.2, although λu was a decreasing function of Ri at lesser stabilities. Oscillations with period T0 are simply alongslope (critical) internal-wave oscillations with a slope-normal wavenumber, which are liable for degeneration into turbulence during their reflection. These critical internal waves may be responsible, at least partly, for weak sustained turbulence often observed in complex-terrain nocturnal boundary layer flows.
Effects of Nonlinearity on Convectively Forced Internal Gravity Waves: Application to a Gravity Wave Drag Parameterization
Authors: Chun Hye-Yeong , Choi Hyun-Joo , Song In-Sun
Published: February 2008

In the present study, the authors propose a way to include a nonlinear forcing effect on the momentum flux spectrum of convectively forced internal gravity waves using a nondimensional numerical model (NDM) in a two-dimensional framework. In NDM, the nonlinear forcing is represented by nonlinear advection terms multiplied by the nonlinearity factor (NF) of the thermally induced internal gravity waves for a given specified diabatic forcing. It was found that the magnitudes of the waves and resultant momentum flux above the specified forcing decrease with increasing NF due to cancellation between the two forcing mechanisms. Using the momentum flux spectrum obtained by the NDM simulations with various NFs, a scale factor for the momentum flux, normalized by the momentum flux induced by diabatic forcing alone, is formulated as a function of NF. Inclusion of the nonlinear forcing effect into current convective gravity wave drag (GWD) parameterizations, which consider diabatic forcing alone by multiplying the cloud-top momentum flux spectrum by the scale factor, is proposed. An updated convective GWD parameterization using the scale factor is implemented into the NCAR Whole Atmosphere Community Climate Model (WACCM). The 10-yr simulation results, compared with those by the original convective GWD parameterization considering diabatic forcing alone, showed that the magnitude of the zonal-mean cloud-top momentum flux is reduced for wide range of phase speed spectrum by about 10%, except in the middle latitude storm-track regions where the cloud-top momentum flux is amplified. The zonal drag forcing is determined largely by the wave propagation condition under the reduced magnitude of the cloud-top momentum flux, and its magnitude decreases in many regions, but there are several areas of increasing drag forcing, especially in the tropical upper mesosphere and lower thermosphere.
A Thermal Plume Model for the Convective Boundary Layer: Representation of Cumulus Clouds
Authors: Rio Catherine , Hourdin Frédéric
Published: February 2008

The “thermal plume model,” a mass-flux scheme combined with a classical diffusive approach, originally developed to represent turbulent transport in the dry convective boundary layer, is extended here to the representation of cloud processes. The modified parameterization is validated in a 1D configuration against results of large eddy simulations (LES), as well as in a 3D configuration against in situ measurements, for a series of cases of dry and cloudy convective boundary layers. Accounting for coherent structures of the mixed layer with the mass-flux scheme improves the representation of the diurnal cycle of the boundary layer, particularly its progressive deepening during the day and the associated near-surface drying. Results also underline the role of the prescription of the mixing of air between the plume and its environment, and of submean-plume fluctuations.
Poleward-Propagating Intraseasonal Monsoon Disturbances in an Intermediate-Complexity Axisymmetric Model
Authors: Bellon Gilles , Sobel Adam
Published: February 2008

A model of intermediate complexity based on quasi-equilibrium theory—a version of the quasi-equilibrium tropical circulation model with a prognostic atmospheric boundary layer, as well as two free-tropospheric modes in momentum, and one each in moisture and temperature—is used in a zonally symmetric aquaplanet configuration to simulate aspects of the South Asian monsoon and its variability. Key qualitative features of both the mean state and the 30–60-day mode of the intraseasonal variability are simulated satisfactorily. The model has two limit cycles of similar period and structure that can account for this mode. Both feature northward propagation of the tropical convergence zone from 5°S to 25°N with a period of about 50 days. The dynamics of the oscillations are investigated. The system reaches a Hopf bifurcation when the asymmetry of the sea surface temperature (SST) forcing is increased. Beyond the bifurcation, the mean flow is linearly unstable, and the one linearly unstable mode is similar in structure and period to the nonlinear mode. The wind-induced surface heat fluxes are necessary to obtain the instability of the mean monsoon flow, as are the 2 degrees of freedom in the vertical structure of both humidity and wind.
Another Look at the Influence of Absorbing Aerosols in Drops on Cloud Absorption: Large Aerosols
Authors: Erlick Carynelisa , Schlesinger Dana
Published: February 2008

Since as early as 1969, solar absorbing aerosols inside of cloud drops have been suggested to influence cloud radiative properties. The absorbing aerosols were invoked to help explain two “anomalies”: 1) the maximum visible albedo of thick stratocumulus clouds is observed to be only 0.7–0.8, rather than close to 1.0 as would be expected from pure water clouds, and 2) the total solar cloud forcing ratio is observed to be near 1.5 for a wide range of clouds, rather than near 1.0 as would be expected from pure water clouds. While subsequent studies refuting absorbing aerosols have been limited to certain aerosol and cloud drop size ranges, in this study the authors explore the potential radiative effects of supermicron dust and soot aerosols in cloud drops, which can have especially high absorption cross sections. Because of the lack of measurements and limited microphysical simulations of such supermicron absorbing aerosols, it is not suggested that the calculations will entirely resolve the two anomalies. However, because these aerosols certainly can exist in the vicinity of clouds, the authors suggest that their potential contribution to the understanding of the anomalies should be explored. This study serves as an initial step toward that goal.
Determination of the Combined Ventilation Factor and Capacitance for Ice Crystal Aggregates from Airborne Observations in a Tropical Anvil Cloud
Authors: Field Paul R. , Heymsfield J. , Bansemer Aaron , Twohy Cynthia H.
Published: February 2008

The ventilation factor and capacitance used in numerical models to represent ice crystal aggregates directly affects the growth rate of the ice crystal aggregates, and consequently the sink of atmospheric water vapor. Currently, numerical models that prognose ice water content (IWC) and water vapor mixing ratio represent the capacitance and ventilation factor of precipitation-sized particles with simplified geometries, such as hexagonal plates. The geometries of actual precipitation-sized particles are often more complex, and a test of the values being employed is needed. Aircraft observations obtained during a Lagrangian spiral descent through the sublimation zone of a tropical anvil cloud have been used to determine an estimate of combined dimensionless capacitance and ventilation factor for the nonpristine geometries exhibited by ice crystal aggregates. By combining measurements of bulk ice water content, the particle size distribution, and environmental subsaturation, the change in ice water content was modeled throughout the spiral descent and compared with observations of the change in ice water content. Uncertainties resulting from potential systematic biases in the measurements and parameterizations used in the analysis were investigated with sensitivity tests. Most of the uncertainty was related to an assumed maximum potential bias in the measurement of IWC of ±45%. The resulting combined ventilation factor and dimensionless capacitance value was 1.3 (with a range of 0.6–1.9, defined by 68% of sensitivity test trials) for a particle size–weighted mean value of (Sc)1/3(Re)1/2 = 14.9 ± 1.7, where Sc is the Schmidt number and Re is the Reynolds number. Results from commonly adopted combinations of ventilation factor relations and capacitances are compared with the observations presented here, and, finally, surrogate dimensionless capacitances are suggested that when combined with commonly used ventilation factor relations are consistent with the results presented herein.
Modeling the Interaction between Cumulus Convection and Linear Gravity Waves Using a Limited-Domain Cloud System–Resolving Model
Authors: Kuang Zhiming
Published: February 2008

A limited-domain cloud system–resolving model (CSRM) is used to simulate the interaction between cumulus convection and two-dimensional linear gravity waves, a single horizontal wavenumber at a time. With a single horizontal wavenumber, soundings obtained from horizontal averages of the CSRM domain allow the large-scale wave equation to be evolved, and thereby its interaction with cumulus convection is modeled. It is shown that convectively coupled waves with phase speeds of 8–13 m s−1 can develop spontaneously in such simulations. The wave development is weaker at long wavelengths (>∼10 000 km). Waves at short wavelengths (∼2000 km) also appear weaker, but the evidence is less clear because of stronger influences from random perturbations. The simulated wave structures are found to change systematically with horizontal wavelength, and at horizontal wavelengths of 2000–3000 km they exhibit many of the basic features of the observed 2-day waves. The simulated convectively coupled waves develop without feedback from radiative processes, surface fluxes, or wave radiation into the stratosphere, but vanish when moisture advection by the large-scale waves is disabled. A similar degree of vertical tilt is found in the simulated convective heating at all wavelengths considered, consistent with observational results. Implications of these results to conceptual models of convectively coupled waves are discussed. In addition to being a useful tool for studying wave–convection interaction, the present approach also represents a useful framework for testing the ability of coarse-resolution CSRMs and single-column models in simulating convectively coupled waves.