bluuebunny/crossref_metadata_2025 huggingface dataset:
Embryonic stem cells form glandular structures and express surfactant protein C following culture with dissociated fetal respiratory tissue
Authors: Denham Mark , Cole Timothy J. , Mollard Richard
Published: January 2006

Mouse embryonic stem cells (MESCs) are pluripotent, theoretically immortal cells derived from the inner cell mass of developing blastocysts. The respiratory epithelium develops from the primitive foregut endoderm as a result of inductive morphogenetic interactions with the surrounding visceral mesoderm. After dissociation of the explanted fetal lung into single cells, these morphogenetic signaling pathways instruct reconstitution of the developing lung according to a process known as organotypic regeneration. Data presented here demonstrate that such fetal lung morphogenetic cues induce MESC derivatives to incorporate into the reforming pseudoglandular-like tubular ducts, display pan-keratin and surfactant protein C (Sftpc) immunoreactivity, and express Sftpc transcripts while displaying a normal diploid karyotype in coculture. The Sftpc inductive capacity of dissociated fetal lung tissue shows stage specificity with 24% of all MESC derivatives displaying Sftpc immunoreactivity after coculture with embryonic day 11.5 (E11.5) lung buds compared with 6% and 0.02% following coculture with E12.5 and E13.5 lung buds, respectively. MESC derivative Sftpc immunoreactivity follows a spatial and temporal specific maturation profile with an initially ubiquitous cellular Sftpc immunostaining pattern becoming apically polarized with time. Directing differentiation of MESCs into respiratory lineages has important implications for cell replacement therapeutics aimed at treating respiratory-specific diseases such as cystic fibrosis and idiopathic pulmonary fibrosis.
Similar chloride channels in the connecting tubule and cortical collecting duct of the mouse kidney
Authors: Nissant Antoine , Paulais Marc , Lachheb Sahran , Lourdel Stéphane , Teulon Jacques
Published: January 2006

Using the patch-clamp technique, we investigated Cl−channels on the basolateral membrane of the connecting tubule (CNT) and cortical collecting duct (CCD). We found a ∼10-pS channel in CNT cell-attached patches. Substitution of sodium gluconate for NaCl in the pipette shifted the reversal potential by +25 mV, whereas N-methyl-d-gluconate chloride had no effect, indicating anion selectivity. On inside-out patches, we determined a selectivity sequence of Cl−> Br−∼ NO3−> F−, which is compatible with that of ClC-K2, a Cl−channel in the distal nephron. In addition, the number of open channels ( NPo) measured in cell-attached patches was significantly increased when Ca2+concentration or pH in the pipette was increased, which is another characteristic of ClC-K. These findings suggest that the basis for this channel is ClC-K2. A similar Cl−channel was found in CCD patches. Because CNT and CCD are heterogeneous tissues, we studied the cellular distribution of the Cl−channel using recording conditions (KCl-rich solution in the pipette) that allowed us to detect simultaneously Cl−channels and inwardly rectifying K+channels. We detected Cl−channels alone in 45% and 42% and K+channels alone in 51% and 58% of CNT and CCD patches, respectively. Cl−and K+channels were recorded simultaneously from two patches (4% of patches) in the CNT and from none of the patches in the CCD. This indicates that Cl−and K+channels are located in different cell types, which we suggest may be the intercalated cells and principal cells, respectively.
Selective sphingosine 1-phosphate 1 receptor activation reduces ischemia-reperfusion injury in mouse kidney
Authors: Awad Alaa S. , Ye Hong , Huang Liping , Li Li , Foss Frank W. , Macdonald Timothy L. , Lynch Kevin R. , Okusa Mark D.
Published: January 2006

The mechanisms involved in renal ischemia-reperfusion injury (IRI) are complex and appear to involve the early participation of bone marrow-derived cells. T lymphocytes participate in the pathogenesis of IRI. Sphingosine 1-phosphate (S1P) induces peripheral T cell depletion. Therefore, we hypothesized that S1P1receptor activation protects kidney from IRI. FTY-720, a non-receptor-selective sphingosine analog, was given intraperitoneally to C57BL/6 mice, and animals were subjected to ischemia for 32 min followed by reperfusion for 24 h. Plasma creatinine, blood count, myeloperoxidase (MPO) activity, and renal histology were determined. IRI led to a marked increase in plasma creatinine, MPO activity, leukocyte infiltration, and vascular permeability. FTY-720 significantly decreased plasma creatinine in a dose-response manner with a maximal reduction of ∼73 and ∼69% with doses of 240 and 48 μg/kg, respectively. MPO, leukocyte infiltration, vascular permeability, and peripheral blood lymphocyte counts were markedly decreased with FTY-720 treatment. The protective effect of FTY-720 was reversed with VPC-44116, a selective S1P1receptor antagonist. Furthermore, SEW-2871, a selective S1P1agonist, significantly decreased plasma creatinine in a dose-response manner with a maximal reduction of ∼70% with a dose of 10 mg/kg. Analysis of kidneys by light microscopy revealed minimal histological signs of ischemic injury with FTY-720 or SEW-2871 treatment compared with the vehicle group. Using RT-PCR, we found a time-dependent increase in the S1P1mRNA expression following IRI that begins after 2 h with the maximum expression at ∼4 h. We conclude that the protective effect of FTY-720 is due primarily to activation of S1P1receptors. The mechanism of protection is not known but may be related to peripheral lymphocyte depletion or direct effects on kidney cells expressing S1P1receptor.
Differential expression of nuclear AT1receptors and angiotensin II within the kidney of the male congenic mRen2.Lewis rat
Authors: Pendergrass Karl D. , Averill David B. , Ferrario Carlos M. , Diz Debra I. , Chappell Mark C.
Published: January 2006

We established a new congenic model of hypertension, the mRen2.Lewis rat and assessed the intracellular expression of angiotensin peptides and receptors in the kidney. The congenic strain was established from the backcross of the (mRen2)27 transgenic rat that expresses the mouse renin 2 gene onto the Lewis strain. The 20-wk-old male congenic rats were markedly hypertensive compared with the Lewis controls (systolic blood pressure: 195 ± 2 vs. 107 ± 2 mmHg, P < 0.01). Although plasma ANG II levels were not different between strains, circulating levels of ANG-(1–7) were 270% higher and ANG I concentrations were 40% lower in the mRen2.Lewis rats. In contrast, both cortical (CORT) and medullary (MED) ANG II concentrations were 60% higher in the mRen2.Lewis rats, whereas tissue ANG I was 66 and 84% lower in CORT and MED. For both strains, MED ANG II, ANG I, and ANG-(1–7) were significantly higher than CORT levels. Intracellular ANG II binding distinguished nuclear (NUC) and plasma membrane (PM) receptor using the ANG II radioligand125I-sarthran. Isolated CORT nuclei exhibited a high density (Bmax>200 fmol/mg protein) and affinity for the sarthran ligand ( KD<0.5 nM); the majority of these sites (>95%) were the AT1receptor subtype. CORT ANG II receptor Bmaxand KDvalues in nuclei were 75 and 50% lower, respectively, for the mRen2.Lewis vs. the Lewis rats. In the MED, the PM receptor density (Lewis: 50 ± 4 vs. mRen2.Lewis: 21 ± 5 fmol/mg protein) and affinity (Lewis: 0.31 ± 0.1 vs. 0.69 ± 0.1 nM) were lower in the mRen2.Lewis rats. In summary, the hypertensive mRen2.Lewis rats exhibit higher ANG II in both CORT and MED regions of the kidney. Evaluation of intracellular ANG II receptors revealed lower CORT NUC and MED PM AT1sites in the mRen2.Lewis. The downregulation of AT1sites in the mRen2.Lewis rats may reflect a compensatory response to dampen the elevated levels of intrarenal ANG II.
WNK kinases influence TRPV4 channel function and localization
Authors: Fu Yi , Subramanya Arohan , Rozansky David , Cohen David M.
Published: January 2006

TRPV4, a renally expressed nonselective cation channel of the transient receptor potential (TRP) family, is gated by hypotonicity. Kinases of the WNK family influence expression and function of the thiazide-sensitive Na+-Cl−cotransporter, and monogenic human hypertension has been linked to mutations in the gene coding for WNK4. Along with TRPV4, WNK isoforms are highly expressed in the distal nephron. We show here that coexpression of WNK4 downregulates TRPV4 function in human embryonic kidney (HEK-293) cells and that this effect is mediated via decreased cell surface expression of TRPV4; total abundance of TRPV4 in whole cell lysates is unaffected. The effect of the related kinase WNK1 on TRPV4 function and surface expression was similar to that of WNK4. Disease-causing point mutations in WNK4 abrogate, but do not eliminate, the inhibitory effect on TRPV4 function. In contrast to wild-type WNK4, a kinase-dead WNK4 point mutant failed to influence TRPV4 trafficking; however, deletion of the entire WNK4 kinase domain did not blunt the effect of WNK4 on localization of TRPV4. Deletion of the extreme COOH-terminal putative coiled-coil domain of WNK4 abolished its effect. In immunoprecipitation experiments, we were unable to detect direct interaction between TRPV4 and either WNK kinase. In aggregate, these data indicate that TRPV4 is functionally regulated by WNK family kinases at the level of cell surface expression. Because TRPV4 and WNK kinases are coexpressed in the distal nephron in vivo and because there is a tendency toward hypercalcemia in TRPV4−/−mice, we speculate that this pathway may impact systemic Ca2+balance. In addition, because WNK kinases and TRPV4 are activated by anisotonicity, they may comprise elements of an osmosensing or osmotically responsive signal transduction cascade in the distal nephron.
Colonic irritation in the rat sensitizes urinary bladder afferents to mechanical and chemical stimuli: an afferent origin of pelvic organ cross-sensitization
Authors: Ustinova Elena E. , Fraser Matthew O. , Pezzone Michael A.
Published: January 2006

Chronic pelvic pain (CPP) disorders frequently overlap. We have demonstrated that acute and chronic colonic irritation can lead to neurogenic cystitis. We hypothesize that acute colonic irritation can sensitize urinary bladder afferents to mechanical and chemical stimuli. Single-unit afferent activity was recorded from fine filaments of the pelvic nerve in urethane-anesthetized Sprague-Dawley female rats before and 1 h after intracolonic administration of trinitrobenzenesulfonic acid (TNBS). Only spontaneously active afferents with receptive fields in the bladder and conduction velocities <2.5 m/s (unmyelinated C-fibers) were studied. Mechanical sensitivity was tested by bladder distension (BD) during saline infusion, whereas chemical sensitivity was tested with intravesical capsaicin, bradykinin, or substance P. Colonic irritation increased the resting firing rate of bladder afferents twofold (1.0 ± 0.2 vs. 0.49 ± 0.2 impulses/s, P < 0.05). Moreover, at low-pressure BDs (10–20 mmHg), a greater percentage of afferents exhibited increased activity following TNBS (73 vs. 27%, P < 0.05). Although the magnitude of the afferent response to BD was unchanged at low pressures, the response was greatly enhanced at pressures 30 mmHg and above (2.36 ± 0.56 vs. 8.55 ± 0.73 impulses/s, P < 0.05). Responses to capsaicin, bradykinin, and substance P were also significantly enhanced following TNBS, and all responses were blocked by bladder denervation. In rats, colonic irritation sensitizes urinary bladder afferents to noxious mechanical and chemical stimuli. Interruption of the neural input to the bladder minimized this effect, suggesting a local afferent pathway from the colon. Thus, the overlap of CPP disorders may be a consequence of pelvic afferent cross-sensitization.
Increased expression but not targeting of ENaC in adrenalectomized rats with PAN-induced nephrotic syndrome
Authors: de Seigneux Sophie , Kim Soo Wan , Hemmingsen Sophie C. , Frøkiær Jørgen , Nielsen Søren
Published: January 2006

Sodium retention is a hallmark of nephrotic syndrome (NS). Puromycin aminonucleoside (PAN)-induced NS is associated with high aldosterone levels and increased ENaC expression and apical targeting. However, the mechanisms associated with increased apical targeting of ENaC in NS remain undefined, and it is unclear whether this is secondary to high aldosterone levels and whether aldosterone and/or apical ENaC targeting are important for the development of sodium retention. This study aimed at uncovering 1) whether aldosterone is essential for sodium retention in PAN-induced NS, 2) whether ENaC expression or apical targeting is secondary to high aldosterone levels, and 3) the role of aldosterone in the dysregulation of sodium transporters in NS. Puromycin treatment of adrenalectomized (ADX) rats supplemented with dexamethasone induced sodium retention despite the absence of aldosterone. Immunocytochemical analyses revealed an absence of enhanced apical targeting of ENaC subunits in PAN-treated ADX (ADX-PAN) rats, with distribution of labeling similar to adrenalectomized dexamethasone-treated control rats (ADX). Moreover, ENaC subunit abundance was increased in ADX-PAN rats. The abundance of aquaporin-2 was unchanged, whereas apical targeting was enhanced. Key sodium transporters were downregulated as previously observed in nonadrenalectomized puromycin-treated rats (Kim SW, Wang W, Nielsen J, Praetorius J, Kwon TH, Knepper MA, Frøkiær J, and Nielsen S. Am J Physiol Renal Physiol 286: F922–F935, 2004), whereas the global expression of the α1-subunit of the Na-K-ATPase was unchanged. In conclusion, PAN treatment in the absence of aldosterone induced sodium retention, increased ENaC expression, but did not change the subcellular distribution of ENaC. This indicates that the previously observed enhanced apical targeting of ENaC in PAN-induced NS (Kim SW, Wang W, Nielsen J, Praetorius J, Kwon TH, Knepper MA, Frøkiær J, and Nielsen S. Am J Physiol Renal Physiol 286: F922–F935, 2004) is caused by aldosterone and that development of sodium retention can occur in the absence of aldosterone in NS.
Brain-Derived Neurotrophic Factor Silences GABA Synapses Onto Hypothalamic Neuroendocrine Cells Through a Postsynaptic Dynamin-Mediated Mechanism
Authors: Hewitt Sarah A. , Bains Jaideep S.
Published: January 2006

In the paraventricular nucleus of the hypothalamus (PVN), experimental stress paradigms that suppress γ-aminobutyric acid (GABA) inputs to parvocellular neuroendocrine cells (PNCs) also increase the expression of brain-derived neurotrophic factor (BDNF). In the adult CNS, BDNF regulates the efficacy of GABAergic transmission, but its contributions to functional changes at inhibitory synapses in the PVN have not been investigated. Analysis of quantal transmission revealed a decrease in the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in response to BDNF with no accompanying changes in their amplitude. These effects were completely blocked by prior inclusion of the TrKB receptor antagonist K252a in the patch pipette. Inclusion of a dynamin inhibitory peptide in the patch pipette also blocked the effects of BDNF, consistent with an all-or-none removal of clusters of postsynaptic GABAA receptors. Finally, to confirm a decrease in the availability of postsynaptic GABAA receptors, we tested the effects of BDNF on focal application of the GABAA agonist muscimol. Postsynaptic responses to muscimol were reduced after BDNF. Collectively, these data indicate that BDNF remodels functional synaptic contacts putatively by reducing the surface expression of postsynaptic GABAA receptors.
Changes in Cortically Related Intermuscular Coherence Accompanying Improvements in Locomotor Skills in Incomplete Spinal Cord Injury
Authors: Norton Jonathan A. , Gorassini Monica A.
Published: January 2006

In human spinal cord injury, the neuronal mechanisms mediating the improvement of locomotor function in response to intensive treadmill training are not well understood. In this study, we examined if such recovery is mediated, in part, by increases in residual corticospinal drive to muscles of the leg during walking. To do this, we measured the coherence of electromyogram (EMG) activity between two antagonist muscles (intermuscular coherence), specifically at frequencies between 24 and 40 Hz, which is thought to indicate common drive to two muscles from corticospinal inputs. In 12 subjects with incomplete spinal cord injury, intermuscular coherence was measured between hamstrings and vastus lateralis EMG that was activated during walking on a motorized treadmill. Before training, appreciable coherence in the 24–40 Hz frequency band was only present in subjects with moderate volitional motor strength in their leg muscles ( n = 8 subjects) compared with subjects with little or no leg muscle strength ( n = 4 subjects), reconfirming that 24–40 Hz frequency coherence is likely mediated by common supraspinal inputs. After training, increases in 24–40 Hz coherence only occurred in the eight subjects with moderate leg muscle strength who also exhibited improvements in locomotor recovery as assessed by the 21 point WISCI II scale (termed responders). In contrast, development of intermuscular coherence in the 24–40 Hz frequency band did not occur in the four subjects with absent or weak muscle strength. These subjects also did not improve in their locomotor ability as reflected in unchanging WISCI II scores (termed nonresponders). Lower-frequency coherence (5–18 Hz), which is thought to contain common drive from spinal inputs, did not change in either group. In a subset of subjects that were previously assessed with transcranial magnetic stimulation (TMS) before and after training ( n = 5 responders and 3 nonresponders), there was a significant and positive relationship between increases in 24–40 Hz coherence and increases in evoked muscle responses to TMS of the primary motor cortex. Taken together, increases in higher-frequency EMG coherence in subjects with residual voluntary muscle strength and its parallel relation to changes in TMS-evoked responses provides further evidence that improvements in locomotor function from treadmill training are mediated, in part, by increases in corticospinal drive to muscles of the leg during walking.
Elimination of allosteric modulation of myocardial KATP channels by ATP and protons in two Kir6.2 polymorphisms found in sudden cardiac death
Authors: Cui Ningren , Li Li , Wang Xueren , Shi Yun , Shi Weiwei , Jiang Chun
Published: January 2006

The major cause of sudden cardiac death (SCD) is ventricular arrhythmias due to unstable myocardial electrical activity in which the ATP-sensitive K+ (KATP) channels play a role. Genetic disruption of these channels predisposes the myocardium to arrhythmias. Two point mutations in the Kir6.2 subunit are found in SCD with acute myocardial infarction. Here we show evidence for the functional consequences of the P266T and R371H variants. Baseline single-channel properties, expression density, and channel modulations were studied in patch clamp. We focused on channel modulations by intracellular ATP and protons, as the concentration of these two important KATP channel regulators changes widely with hypoxic ischemia. We found that both variants expressed functional currents even though they occur at two highly conserved regions. The open state probability of P266T was twice as high as the wild-type (WT) channel, whereas its channel density was only ∼20% of the WT channel. Although the outward current was not affected by these two mutations at neutral pH, it was ∼20% lower at acidic pH in the P266T than in the WT channel. Both P266T and R371H mutations significantly reduced ATP sensitivity and increased pH sensitivity. More dramatically, allosteric regulation by intracellular ATP and protons was almost completely eliminated in the polymorphic P266T and R371H channels. Such an abnormality was seen in both inward and outward currents. Given the importance and beneficial effects of allosteric regulation in cellular responses to metabolic stress, the loss of such a regulatory mechanism in the P266T and R371H variants appears consistent with the adverse consequences occurring during acute myocardial infarction in patients.
Transcriptomes of purified gastric ECL and parietal cells: identification of a novel pathway regulating acid secretion
Authors: Lambrecht Nils W. G. , Yakubov Iskandar , Zer Cindy , Sachs George
Published: January 2006

The gastric entero-chromaffin-like (ECL) cell plays a key regulatory role in peripheral regulation of acid secretion due to the release of histamine that stimulates acid secretion by the parietal cell. Studies in intact animals, gastric glands, and isolated cells after short-term culture have shown expression of stimulatory CCK2 and PAC1 and inhibitory SST2 and Gal1 receptors as well as histidine decarboxylase. However, the pattern of its gene expression as a neuroendocrine cell has not been explored. Comparison of gene expression by 95% pure ECL cells obtained by density gradient, elutriation, and fluorescence-assisted cell sorting with isolates of the intact fundic gastric epithelium (i.e., “subtractive hybridization”) identified a variety of additional expressed gene families characteristic of this neuroendocrine cell. These include genes 1) involved in neuropeptide synthesis and secretory vesicle exocytosis, 2) involved in control of inflammation, 3) implicated in healing of the epithelium, 4) encoding inhibitory Giprotein-coupled receptors, 5) playing a role in neuroendocrine regulation of food intake, and 6) encoding proteins likely involved in maintenance of circadian rhythm, in addition to the ECL cell-specific genes histidine decarboxylase and monoamine transporter. Particularly, the inhibitory apelin receptor gene, APJ, was highly expressed in the ECL cell preparation. Because parietal cells express apelin, immunohistochemical and functional studies showed that there is an inhibitory feed back loop between the parietal and ECL cell during gastrin stimulation, providing evidence for a novel pathway of downregulation of acid secretion due to interaction between these two cell types.
Neural Mechanisms of Cognitive Control: An Integrative Model of Stroop Task Performance and fMRI Data
Authors: Herd Seth A. , Banich Marie T. , O'Reilly Randall C.
Published: January 2006

We address the connection between conceptual knowledge and cognitive control using a neural network model. This model extends a widely held theory of cognitive control [Cohen, J. D., Dunbar, K., & McClelland, J. L. On the control of automatic processes: A parallel distributed processing model of the Stroop effect. Psychological Review, 97, 332-361, 1990] so that it can explain new empirical findings. Leveraging other computational modeling work, we hypothesize that representations used for task control are recruited from preexisting representations for categories, such as the concept of color relevant to the Stroop task we model here. This hypothesis allows the model to account for otherwise puzzling fMRI results, such as increased activity in brain regions processing to-be-ignored information. In addition, biologically motivated changes in the model's pattern of connectivity show how global competition can arise when inhibition is strictly local, as it seems to be in the cortex. We also discuss the potential for this theory to unify models of task control with other forms of attention.
Prefrontal Activity and Diagnostic Monitoring of Memory Retrieval: fMRI of the Criterial Recollection Task
Authors: Gallo David A. , Kensinger Elizabeth A. , Schacter Daniel L.
Published: January 2006

According to the distinctiveness heuristic, subjects rely more on detailed recollections (and less on familiarity) when memory is tested for pictures relative to words, leading to reduced false recognition. If so, then neural regions that have been implicated in effortful postretrieval monitoring (e.g., dorsolateral prefrontal cortex) might be recruited less heavily when trying to remember pictures. We tested this prediction with the criterial recollection task. Subjects studied black words, paired with either the same word in red font or a corresponding colored picture. Red words were repeated at study to equate recognition hits for red words and pictures. During fMRI scanning, alternating red word memory tests and picture memory tests were given, using only white words as test stimuli (say “yes” only if you recollect a corresponding red word or picture, respectively). These tests were designed so that subjects had to rely on memory for the criterial information. Replicating prior behavioral work, we found enhanced rejection of lures on the picture test compared to the red word test, indicating that subjects had used a distinctiveness heuristic. Critically, dorsolateral prefrontal activity was reduced when rejecting familiar lures on the picture test, relative to the red word test. These findings indicate that reducing false recognition via the distinctiveness heuristic is not heavily dependent on frontally mediated postretrieval monitoring processes.
Morphological Processing in a Second Language: Behavioral and Event-related Brain Potential Evidence for Storage and Decomposition
Authors: Hahne Anja , Mueller Jutta L. , Clahsen Harald
Published: January 2006

This study reports the results of two behavioral and two event-related brain potential experiments examining the processing of inflected words in second-language (L2) learners with Russian as their native language. Two different subsystems of German inflection were studied, participial inflection and noun plurals. For participial forms, L2 learners were found to widely generalize the -t suffixation rule in a nonce-word elicitation task, and in the event-related brain potential experiment, they showed an anterior negativity followed by a P600-both results resembling previous findings from native speakers of German on the same materials. For plural formation, the L2 learners displayed different preference patterns for regular and irregular forms in an off-line plural judgment task. Regular and irregular plural forms also differed clearly with regard to their brain responses. Whereas overapplications of the -s plural rule produced a P600 component, overapplications of irregular patterns elicited an N400. In contrast to native speakers of German, however, the L2 learners did not show an anterior negativity for -s plural overapplications. Taken together, the results show clear dissociations between regular and irregular inflection for both morphological subsystems. We argue that the two processing routes posited by dual-mechanism models of inflection (lexical storage and morphological decomposition) are also employed by L2 learners.
Dissociating Task-set Selection from Task-set Inhibition in the Prefrontal Cortex
Authors: Mayr Ulrich , Diedrichsen Jörn , Ivry Richard , Keele Steven W.
Published: January 2006

Patients with focal lesions in the left (n = 7) and right (n = 4) prefrontal cortex were compared with controls (n = 16) in a task-switching experiment using four different, simple spatial tasks. Each of these tasks involved a left-right decision, either regarding an arrow, the word “left” or “right”, a circle position, or the direction of a moving line. We compared performance on trials that required rule switches versus rule repetitions (local switch costs) and we compared performance between blocks with bivalent stimuli (two dimensions present) and blocks with univalent stimuli (only one dimension present) to assess global switch costs. Patients with left prefrontal lesions, but not patients with right prefrontal lesions, exhibited increased costs on trials in which the relevant dimension switched (local switch costs), but also on no-switch trials with bivalent stimuli (global costs). We also assessed task-set inhibition in the form of the backward-inhibition effect [increased response times to recently abandoned tasks; Mayr, U., & Keele, S. Changing internal constraints on action: The role of backward inhibition. Journal of Experimental Psychology: General, 129, 4-26, 2000]. Although left frontal patients showed normal inhibition, right frontal patients showed no evidence for inhibition. These results suggest a neurocognitive dissociation between task-set selection and inhibition.
The Status of Allies in Pre-Islamic and Early Islamic Arabian Society
Authors: Landau-Tasseron Ella
Published: January 2006

In pre-Islamic and early Islamic times many tribes accepted outsiders into their midst by means of a certain type of alliance. In this article I investigate the integration and the status of such allies within the host tribes. As indicators of integration, I examine marriage and adoption cases involving allies, and the way in which allies used tribal nisbas. The status of allies is reflected in accounts of their conduct and the ways in which they were treated. I conclude that there were no strict rules governing the integration of allies; and that not all allies shared the same status even though they belonged to the same category.
Green’s Functions for a Two‐Phase Infinite Magneto‐Electro‐Elastic Plane
Authors: Jiang Aimin , Ding Haojiang , Wu Guoquan
Published: January 2006

Based on the governing equations of magneto‐electro‐elastic media, the general solutions in the case of distinct eigenvalues and is introduced and expressed in four harmonic functions. Then, the Green’s functions for point forces, point charge and point current acting in the interior of a two‐phase infinite magneto‐electro‐elastic plane in the case of distinct or multiple eigenvalues are given using the method of mirror image source.
On the Damage Evolution and the Mechanical Degradation of Glass‐Fibre Non‐Crimp Fabric Reinforced Epoxy Under Tensile Loading: Experimental and Finite Element Modelling
Authors: Gagel Andreas , M¨ller Christian , Schulte Karl
Published: January 2006

The stiffness and damage evolution in a quasi‐static tensile loaded non‐crimp fabric reinforced epoxy was measured. To determine the effective stiffness of the damaged material numerically a finite element analysis was performed. The finite element analysis bases solely on the measured ±45° and 90°‐ crack densities and on ply properties calculated by the Rule of Mixtures. The measured and calculated effective tensile stiffness were compared and a fair agreement could be found.
On the Horizontal Scale of Elevation Dependence of Australian Monthly Precipitation
Authors: Sharples Jason J. , Hutchinson Michael F. , Jellett Damian R.
Published: January 2006

Determination of the scale of the interaction between precipitation and topography is important for the accurate interpolation of rainfall in mountainous areas and also provides insight into the physical processes involved. In this paper, trivariate thin-plate smoothing splines are used to investigate the scale of interaction between monthly precipitation and topography by interpolating monthly rainfall over three subregions of the Australian continent, incorporating different climatic conditions and rainfall types. The interpolations are based upon elevations derived from digital elevation models (DEMs) of various resolutions. All of the DEMs are local averages of version 2.0 of the 9-s-resolution DEM of Australia. The results suggest that the optimal scale of the interaction between precipitation and topography, as it pertains to the elevation-dependent interpolation of monthly precipitation in Australia, is between 5 and 10 km. This is in agreement with results of similar studies that addressed daily precipitation over Switzerland.
Interannual Variability of Water Demand and Summer Climate in Albuquerque, New Mexico
Authors: Gutzler David S. , Nims Joshua S.
Published: January 2006

The effects of interannual climate variability on water demand in Albuquerque, New Mexico, are assessed. This city provides an ideal setting for examining the effects of climate on urban water demand, because at present the municipal water supply is derived entirely from groundwater, making supply insensitive to short-term climate variability. There is little correlation between interannual variability of climate and total water demand—a result that is consistent with several previous studies. However, summertime residential demand, which composes about one-quarter of total annual demand in Albuquerque, is significantly correlated with summer-season precipitation and average daily maximum temperature. Furthermore, regressions derived from year-to-year changes in these variables are shown to isolate the climatic modulation of residential water demand effectively. Over 60% of the variance of year-to-year changes in summer residential demand is accounted for by interannual temperature and precipitation changes when using a straightforward linear regression model, with precipitation being the primary correlate. Long-term trends in water demand follow population growth closely until 1994, after which time a major water conservation effort led to absolute decreases in demand in subsequent years. The effectiveness of the conservation efforts can be quantified by applying the regression model, thus removing the year-to-year variations associated with short-term climate fluctuations estimated from the preconservation period. The preconservation regression provides a good fit to interannual summer residential demand in subsequent years, demonstrating that the regression model has successfully isolated the climatic component of water demand. The quality of this fit during a period of sharply reduced demand suggests that the conservation program has effectively targeted the nonclimatically sensitive component of water demand and has sharpened the climatically sensitive component of demand to a level closer to the consumption that is “climatically needed.”
Bulk Scattering Properties for the Remote Sensing of Ice Clouds. Part I: Microphysical Data and Models
Authors: Baum Bryan A. , Heymsfield Andrew J. , Yang Ping , Bedka Sarah T.
Published: January 2006

This study reports on the use of in situ data obtained in midlatitude and tropical ice clouds from airborne sampling probes and balloon-borne replicators as the basis for the development of bulk scattering models for use in satellite remote sensing applications. Airborne sampling instrumentation includes the two-dimensional cloud (2D-C), two-dimensional precipitation (2D-P), high-volume precipitation spectrometer (HVPS), cloud particle imager (CPI), and NCAR video ice particle sampler (VIPS) probes. Herein the development of a comprehensive set of microphysical models based on in situ measurements of particle size distributions (PSDs) is discussed. Two parameters are developed and examined: ice water content (IWC) and median mass diameter Dm. Comparisons are provided between the IWC and Dm values derived from in situ measurements obtained during a series of field campaigns held in the midlatitude and tropical regions and those calculated from a set of modeled ice particles used for light-scattering calculations. The ice particle types considered in this study include droxtals, hexagonal plates, solid columns, hollow columns, aggregates, and 3D bullet rosettes. It is shown that no single habit accurately replicates the derived IWC and Dm values, but a mixture of habits can significantly improve the comparison of these bulk microphysical properties. In addition, the relationship between Dm and the effective particle size Deff, defined as 1.5 times the ratio of ice particle volume to projected area for a given PSD, is investigated. Based on these results, a subset of microphysical models is chosen as the basis for the development of ice cloud bulk scattering models in Part II of this study.
Bulk Scattering Properties for the Remote Sensing of Ice Clouds. Part II: Narrowband Models
Authors: Baum Bryan A. , Yang Ping , Heymsfield Andrew J. , Platnick Steven , King Michael D. , Hu Y-X. , Bedka Sarah T.
Published: January 2006

This study examines the development of bulk single-scattering properties of ice clouds, including single-scattering albedo, asymmetry factor, and phase function, for a set of 1117 particle size distributions obtained from analysis of the First International Satellite Cloud Climatology Project Regional Experiment (FIRE)-I, FIRE-II, Atmospheric Radiation Measurement Program intensive observation period, Tropical Rainfall Measuring Mission Kwajalein Experiment (KWAJEX), and the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) data. The primary focus is to develop band-averaged models appropriate for use by the Moderate Resolution Imaging Spectroradiometer (MODIS) imager on the Earth Observing System Terra and Aqua platforms, specifically for bands located at wavelengths of 0.65, 1.64, 2.13, and 3.75 μm. The results indicate that there are substantial differences in the bulk scattering properties of ice clouds formed in areas of deep convection and those that exist in areas of much lower updraft velocities. Band-averaged bulk scattering property results obtained from a particle-size-dependent mixture of ice crystal habits are compared with those obtained assuming only solid hexagonal columns. The single-scattering albedo is lower for hexagonal columns than for a habit mixture for the 1.64-, 2.13-, and 3.75-μm bands, with the differences increasing with wavelength. In contrast, the asymmetry factors obtained from the habit mixture and only the solid hexagonal column are most different at 0.65 μm, with the differences decreasing as wavelength increases. At 3.75 μm, the asymmetry factor results from the two habit assumptions are almost indistinguishable. The asymmetry factor, single-scattering albedo, and scattering phase functions are also compared with the MODIS version-1 (V1) models. Differences between the current and V1 models can be traced to the microphysical models and specifically to the number of both the smallest and the largest particles assumed in the size distributions.
Simple Empirical Models for Estimating the Increase in the Central Pressure of Tropical Cyclones after Landfall along the Coastline of the United States
Authors: Vickery Peter J.
Published: January 2006

Modeling the increase in the central pressure of tropical cyclones following landfall plays a critical role in the estimation of the hurricane wind hazard at locations removed from the coastline. This paper describes the development of simple empirical models for estimating the rate at which tropical cyclones decay after making landfall. For storms making landfall along the Gulf of Mexico Coast and the coast of the Florida Peninsula, it is shown that the rate of storm filling is proportional to the central pressure difference and translation speed at the time of landfall and is inversely proportional to the radius to maximum winds. Along the Atlantic Coast the effect of radius to maximum winds does not play as significant a role in the rate of storm decay as compared with that seen in Florida and along the Gulf Coast. The models developed here can readily be included in any hurricane simulation model designed for estimating wind speeds in the United States.
Evaluation of Snow Depth and Soil Temperatures Predicted by the Hydro–Thermodynamic Soil–Vegetation Scheme Coupled with the Fifth-Generation Pennsylvania State University–NCAR Mesoscale Model
Authors: Narapusetty Balachandrudu , Mölders Nicole
Published: January 2006

The Hydro–Thermodynamic Soil–Vegetation Scheme (HTSVS) coupled in a two-way mode with the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (NCAR) Mesoscale Meteorological Model (MM5) is evaluated for a typical snowmelt episode in the Baltic region by means of observations at 25 soil temperature, 355 snow-depth, and 344 precipitation sites that have, in total, 1000, 1775, and 1720 measurements, respectively. The performance with respect to predicted near-surface meteorological fields is evaluated using reanalysis data. Snow depth depends on snow metamorphism, sublimation, and snowfall. Because in the coupled model these processes are affected by the predicted surface radiation fluxes and cloud and precipitation processes, sensitivity studies are performed with two different cloud microphysical schemes and/or radiation schemes. Skill scores are calculated as a quality measure for the coupled model’s performance for a typical forecast range of 120 h for a typical spring (snowmelt) weather situation in the Baltic region. Discrepancies between predicted and observed snow-depth changes relate to the coupling. Enhanced water supply to the atmosphere, which results from water that was assumed to be open in MM5 but was actually ice covered in nature, finally leads to an overestimation of snowfall (input to HTSVS) and changes in snow depth (output). The resolution-dependent discrepancies between the terrain height in the model and real world also lead to snowfall where none occurred. For heavy snowfall the performance of the coupled model with respect to predicted snow-depth changes becomes nearly independent of the choice of the cloud microphysical and radiation schemes. As compared with observed changes in snow depth, the coupled model simulation using the Schultz scheme in conjunction with the radiation scheme from the Community Climate Model, version 2, (CCM2) predicts snow-depth changes of less than 2.5 mm considerably better than the other combinations that were tested. For thick snowpacks, the accuracy of the snow-depth decrease resulting from metamorphism strongly depends on the initial value of snow density. The coupled model acceptably captures the soil temperature diurnal cycles, the observed soil temperature increase with time, and the soil temperature behavior with depth. In general, discrepancies between simulated and observed soil temperatures decrease with soil depth. Simulations performed with the so-called CLOUD radiation scheme capture soil temperature minima and maxima better than do simulations performed with the CCM2 scheme.
A Large-Droplet Mode and Prognostic Number Concentration of Cloud Droplets in the Colorado State University Regional Atmospheric Modeling System (RAMS). Part II: Sensitivity to a Colorado Winter Snowfall Event
Authors: Saleeby Stephen M. , Cotton William R.
Published: January 2006

This paper is the second in a two-part series describing recent additions to the microphysics module of the Regional Atmospheric Modeling System (RAMS) at Colorado State University. These changes include the addition of a large-cloud-droplet mode (40–80 μm in diameter) into the liquid-droplet spectrum and the parameterization of cloud-droplet nucleation through activation of cloud condensation nuclei (CCN) and giant CCN (GCCN). The large-droplet mode was introduced to represent more precisely the natural dual mode of the cloud-droplet distribution. The parameterized droplet nucleation replaces the former estimation of cloud-droplet formation solely from supersaturation calculations. In Part I of this series, details of the improvements to the microphysics were presented, including the set of equations governing the development of cloud droplets in the Lagrangian parcel model that was employed to parameterize this complex process. Supercell simulations were examined with respect to the model sensitivity to the presence and concentration of large cloud droplets, CCN, and GCCN. Part II examines the sensitivity of the model microphysics to imposed aerosol variations in a wintertime snowfall event that occurred over Colorado on 28–29 February 2004. Model analyses and sensitivity are compared with the real-time forecast version 4.3 of RAMS as well as selected snowpack telemetry (SNOTEL) accumulated precipitation data and surface data from Storm Peak Laboratory in Steamboat Springs, Colorado.
Wintertime Cold-Air Pools in the Bavarian Danube Valley Basin: Data Analysis and Idealized Numerical Simulations
Authors: Zängl Günther
Published: January 2006

This paper investigates wintertime cold-air pools in a basinlike part of the Danube Valley, located in the German state of Bavaria. Specifically, the focus is on cold-pool events restricted to the basin area, that is, not extending to the more elevated parts of the Alpine foreland. An analysis of observational data indicates that the delay of warm-air advection in the basin area relative to the Alpine foreland plays a major role in these events. However, the relationship between warming in the Alpine foreland and a temperature deficit in the northeast–southwest-oriented basin appears to depend sensitively on the ambient wind direction. A statistically significant correlation is found only for westerly and southerly wind directions but not for easterly directions. To examine the dynamical reasons for this phenomenon, idealized numerical simulations have been conducted. They are initialized with a pronounced cold pool in the basin area and examine the response of the cold pool to the dynamical forcing imposed by a geostrophically balanced large-scale wind field of various directions and strengths. Sensitivity tests consider the effects of the surrounding mountain ranges and of turbulent vertical mixing. The model results indicate that the most important dynamical processes capable of dissolving cold-air pools in a large basin are (i) ageostrophic advection of the cold air toward lower ambient pressure and (ii) downstream advection by the ambient flow. The former might also be interpreted as an adjustment of the cold air to the external pressure gradient, which can be balanced by the development of a spatial gradient in cold-pool depth. In principle, both advection processes are most effective in the along-basin direction because the advected air does not have to surmount significant topographic obstacles. However, a combination of several effects induced by the surrounding mountain ranges—for example, upstream flow deceleration and wake formation—modifies the dependence of the cold-pool persistence on the ambient wind direction. In agreement with observational data, the simulations with full topography predict a higher tendency for cold-pool persistence in the Danube basin for westerly and southerly flow than for easterly flow. Turbulent vertical mixing is found to make a significant contribution to the erosion of cold pools, but its effect is smaller than the sensitivity to the ambient wind direction.
Numerical Experiments on the Seasonal Variations of the Oyashio near the East Coast of Japan
Authors: Tatebe Hiroaki , Yasuda Ichiro
Published: January 2006

Seasonal variations of the Oyashio near the east coast of Japan are examined using a simple layered model with a localized diapycnal transport due to the strong tidal mixing around the Kuril Islands. The modeled southernmost latitude is located at around 40°N in spring and 42°N in autumn. The southwestward Oyashio transport in the upper layers and depth-integrated transport become large (small) during winter–spring (summer–autumn). These results are in agreement with observations. The seasonal variation of the southernmost latitude is mainly caused by the baroclinic velocity anomalies off Tohoku and Hokkaido, Japan, which have been excited by the wind stress changes along the west coast of North America, the Kamchatka Peninsula, and the model northern boundary. This is different from the previous studies that emphasized the importance of direct barotropic response of the ocean to the basin-scale wind stress changes. For comparison, an additional experiment in which the diapycnal transport around the Kuril Islands is not included is performed. In this case, the annual-mean Oyashio does not extend south of the wind-driven gyre boundary and the variation of the southernmost latitude is small, even though the baroclinic velocity anomalies are similar to the ones in the case with the diapycnal transport. This is because the annual-mean Oyashio velocities are larger than the anomalies and cannot be distorted, whereas the annual-mean Oyashio in the case with diapycnal transport is weak in intrusion of the wind-driven gyre boundary and can be easily changed by the velocity anomalies. It is suggested that the reproduction of the seasonal variation of the Oyashio southernmost latitude depends on whether the annual-mean Oyashio intrusion could be reproduced adequately in the numerical model.