bluuebunny/crossref_metadata_2025 huggingface dataset:
Tastants evoke cAMP signal in taste buds that is independent of calcium signaling
Authors: Trubey Kristina R. , Culpepper Schartess , Maruyama Yutaka , Kinnamon Sue C. , Chaudhari Nirupa
Published: March 2006

We previously showed that rat taste buds express several adenylyl cyclases (ACs) of which only AC8 is known to be stimulated by Ca2+. Here we demonstrate by direct measurements of cAMP levels that AC activity in taste buds is stimulated by treatments that elevate intracellular Ca2+. Specifically, 5 μM thapsigargin or 3 μM A-23187 (calcium ionophore), both of which increase intracellular Ca2+ concentration ([Ca2+]i), lead to a significant elevation of cAMP levels. This calcium stimulation of AC activity requires extracellular Ca2+, suggesting that it is dependent on Ca2+ entry rather than release from stores. With immunofluorescence microscopy, we show that the calcium-stimulated AC8 is principally expressed in taste cells that also express phospholipase Cβ2 (i.e., cells that elevate [Ca2+]i in response to sweet, bitter, or umami stimuli). Taste transduction for sucrose is known to result in an elevation of both cAMP and calcium in taste buds. Thus we tested whether the cAMP increase in response to sucrose is a downstream consequence of calcium elevation. Even under conditions of depletion of stored and extracellular calcium, the cAMP response to sucrose stimulation persists in taste cells. The cAMP signal in response to monosodium glutamate stimulation is similarly unperturbed by calcium depletion. Our results suggest that tastant-evoked cAMP signals are not simply a secondary consequence of calcium modulation. Instead, cAMP and released Ca2+ may represent independent second messenger signals downstream of taste receptors.
Roles of CaM kinase II and phospholamban in SNP-induced relaxation of murine gastric fundus smooth muscles
Authors: Kim Minkyung , Han In Soo , Koh Sang Don , Perrino Brian A.
Published: March 2006

The mechanisms by which nitric oxide (NO) relaxes smooth muscles are unclear. The NO donor sodium nitroprusside (SNP) has been reported to increase the Ca2+release frequency (Ca2+sparks) through ryanodine receptors (RyRs) and activate spontaneous transient outward currents (STOCs), resulting in smooth muscle relaxation. Our findings that caffeine relaxes and hyperpolarizes murine gastric fundus smooth muscles and increases phospholamban (PLB) phosphorylation by Ca2+/calmodulin (CaM)-dependent protein kinase II (CaM kinase II) suggest that PLB phosphorylation by CaM kinase II participates in smooth muscle relaxation by increasing sarcoplasmic reticulum (SR) Ca2+uptake and the frequencies of SR Ca2+release events and STOCs. Thus, in the present study, we investigated the roles of CaM kinase II and PLB in SNP-induced relaxation of murine gastric fundus smooth muscles. SNP hyperpolarized and relaxed gastric fundus circular smooth muscles and activated CaM kinase II. SNP-induced CaM kinase II activation was prevented by KN-93. Ryanodine, tetracaine, 2-aminoethoxydiphenylborate, and cyclopiazonic acid inhibited SNP-induced fundus smooth muscle relaxation and CaM kinase II activation. The Ca2+-activated K+channel blockers iberiotoxin and apamin inhibited SNP-induced hyperpolarization and relaxation. The soluble guanylate cyclase inhibitor 1 H-[1,2,4]oxadiazolo-[4,3-α]quinoxalin-1-one inhibited SNP-induced relaxation and CaM kinase II activation. The membrane-permeable cGMP analog 8-bromo-cGMP relaxed gastric fundus smooth muscles and activated CaM kinase II. SNP increased phosphorylation of PLB at Ser16and Thr17. Thr17phosphorylation of PLB was inhibited by cyclopiazonic acid and KN-93. Ser16and Thr17phosphorylation of PLB was sensitive to 1 H-[1,2,4]oxadiazolo-[4,3-α]quinoxalin-1-one. These results demonstrate a novel pathway linking the NO-soluble guanylyl cyclase-cGMP pathway, SR Ca2+release, PLB, and CaM kinase II to relaxation in gastric fundus smooth muscles.
Stretch-induced phosphorylation of focal adhesion kinase in endothelial cells: role of mitochondrial oxidants
Authors: Ali Mir H. , Mungai Paul T. , Schumacker Paul T.
Published: March 2006

Mechanical stretch activates a number of signaling pathways in endothelial cells, and it elicits a variety of functional responses including increases in the phosphorylation of focal adhesion kinase (FAK), a nonreceptor tyrosine kinase involved in integrin-mediated signal transduction. Stretch also triggers an increase in the generation of reactive oxygen species (ROS), which may function as second messengers in the signal transduction cascades that activate cellular responses to strain. Mitochondria represent an important source of ROS in the cell, and these organelles may release ROS in response to strain by virtue of their attachment to cytoskeletal proteins. We therefore tested whether cyclic stretch increases FAK phosphorylation at Tyr397 through a mitochondrial ROS signaling pathway in bovine pulmonary artery endothelial cells (BPAEC). Oxidant signaling, measured using 2′7′-dichlorofluorescin (DCFH), increased 152 ± 16% during 1.5 h of cyclic strain relative to unstrained controls. The mitochondrial inhibitors diphenylene iodonium (5 μM) or rotenone (2 μM) attenuated this increase, whereas l-nitroarginine (100 μM), allopurinol (100 μM), or apocynin (30 μM) had no effect. The antioxidants ebselen (5 μM) and dithiodidiethyldithiocarbamate (1 mM) inhibited the strain-induced increase in oxidant signaling, but Hb (5 μM) had no effect. These results indicate that strain induces oxidant release from mitochondria. Treatment with cytochalasin D (5 μM) abrogated strain-induced DCFH oxidation in BPAEC, indicating that actin filaments were required for stretch-induced mitochondrial ROS generation. Cyclic strain increased FAK phosphorylation at Tyr397, but this was abolished by mitochondrial inhibitors as well as by antioxidants. Strain-induced FAK phosphorylation was abrogated by inhibition of protein kinase C (PKC) with Ro-31-8220 or Gö-6976. These findings indicate that mitochondrial oxidants generated in response to endothelial strain trigger FAK phosphorylation through a signaling pathway that involves PKC.
Duodenal cytochrome b: a novel ferrireductase in airway epithelial cells
Authors: Turi Jennifer L. , Wang Xinchao , McKie Andrew T. , Nozik-Grayck Eva , Mamo Lisa B. , Crissman Kay , Piantadosi Claude A. , Ghio Andrew J.
Published: March 2006

Catalytically active iron in the lung causes oxidative stress and promotes microbial growth that can be limited by intracellular sequestration of iron within ferritin. Because cellular iron uptake requires membrane ferrireductase activity that in the gut can be provided by duodenal cytochrome b (Dcytb), we sought Dcytb in the lung to test the hypothesis that it contributes to epithelial iron regulation by reducing Fe3+ for cellular iron transport. Dcytb expression was found in respiratory epithelium in vitro and in vivo and was responsive to iron concentration. Iron transport was measured in human bronchial epithelial (HBE) cells using inductively coupled plasma atomic emission spectroscopy and was demonstrated to be partially inhibited in the presence of Dcytb-blocking antibody, suggesting that Dcytb reduces Fe3+ for cellular iron transport. A definite source of reducing equivalents for Dcytb was sought but not identified. We found no evidence that ascorbate was involved but did demonstrate that O2−· production decreased when Dcytb function was blocked. The presence of Dcytb in airway epithelial cells and its regulation by iron therefore may contribute to pulmonary cytoprotection.
Epithelial-Restricted Gene Profile of Primary Cultures from Human Prostate Tumors: A Molecular Approach to Predict Clinical Behavior of Prostate Cancer
Authors: Nanni Simona , Priolo Carmen , Grasselli Annalisa , D'Eletto Manuela , Merola Roberta , Moretti Fabiola , Gallucci Michele , De Carli Piero , Sentinelli Steno , Cianciulli Anna Maria , Mottolese Marcella , Carlini Paolo , Arcelli Diego , Helmer-Citterich Mauro , Gaetano Carlo , Loda Massimo , Pontecorvi Alfredo , Bacchetti Silvia , Sacchi Ada , Farsetti Antonella
Published: March 2006

The histopathologic and molecular heterogeneity of prostate cancer and the limited availability of human tumor tissue make unraveling the mechanisms of prostate carcinogenesis a challenging task. Our goal was to develop an ex vivo model that could be reliably used to define a prognostic signature based on gene expression profiling of cell cultures that maintained the tumor phenotype. To this end, we derived epithelial cultures from tissue explanted from 59 patients undergoing radical prostatectomy or cistoprostatectomy because of prostate benign hyperplasia/prostate cancer or bladder carcinoma. Patient selection criteria were absence of hormonal neoadjuvant treatment before surgery and diagnosis of clinically localized disease. Using this unique experimental material, we analyzed expression of 22,500 transcripts on the Affymetrix Human U133A GeneChip platform (Affymetrix, Inc., High Wycombe, United Kingdom). Cultures from normal/hyperplastic tissues with a prevalent luminal phenotype and from normal prostate epithelial tissue with basal phenotype (PrEC) served as controls. We have established a large number of prostate primary cultures highly enriched in the secretory phenotype. From them, we derived an epithelial-restricted transcriptional signature that (a) differentiated normal from tumor cells and (b) clearly separated cancer-derived lines into two distinct groups, which correlated with indolent or aggressive clinical behavior of the disease. Our findings provide (a) a method to expand human primary prostate carcinoma cells with a luminal phenotype, (b) a powerful experimental model to study primary prostate cancer biology, and (c) a novel means to characterize these tumors from a molecular genetic standpoint for prognostic and/or predictive purposes. (Mol Cancer Res 2006;4(2):79–92)
Nuclear Factor-κB Dimer Exchange Promotes a p21waf1/cip1 Superinduction Response in Human T Leukemic Cells
Authors: Chang Pei-Yun , Miyamoto Shigeki
Published: March 2006

The nuclear factor-κB (NF-κB)/Rel transcription factors are recognized as critical apoptosis regulators. We reported previously that NF-κB contributes to chemoresistance of CEM human T leukemic cells in part through its ability to induce p21waf1/cip1. Here, we provide evidence that sequential NF-κB-activating signals induce heightened NF-κB DNA binding and p21waf1/cip1 induction in CEM and additional T leukemic cell lines. This response arises from exceedingly low basal expression of the p105/p50 NF-κB subunit encoded by the NFKB1 gene in these cell lines. An initial NF-κB activation event enhances the recruitment of p65 and ELF1 to the NFKB1 promoter, leading to p65- and ELF1-dependent synthesis of p105/p50, which promotes an exchange of NF-κB complexes to p50-containing complexes with an increased DNA-binding activity to certain NF-κB target elements. Subsequent stimulation of these cells with an anticancer agent, etoposide, results in augmented NF-κB-dependent p21waf1/cip1 induction and increased chemoresistance of the leukemia cells. Thus, we propose that low basal NFKB1 expression coupled with sequential NF-κB activation events can promote increased chemoresistance in certain T leukemic cells. (Mol Cancer Res 2006;4(2):101–12)
Overcoming Physiologic Barriers to Cancer Treatment by Molecularly Targeting the Tumor Microenvironment
Authors: Cairns Rob , Papandreou Ioanna , Denko Nicholas
Published: March 2006

It is widely recognized that the vasculature of the tumor is inadequate to meet the demands of the growing mass. The malformed vasculature is at least in part responsible for regions of the tumor that are hypoxic, acidotic, and exposed to increased interstitial fluid pressure. These unique aspects of the tumor microenvironment have been shown to act as barriers to conventional chemotherapy or radiation-based therapies. It now seems that while the vasculature initiates these tumor-specific conditions, the cells within the tumor respond to these stresses and add to the unique solid tumor physiology. Gene expression changes have been reported in the tumor for vascular endothelial growth factor, carbonic anhydrase IX, and pyruvate dehydrogenase kinase 1. The activity of these gene products then influences the tumor physiology through alterations in vascular permeability and interstitial fluid pressure, extracellular acidosis, and mitochondrial oxygen consumption and hypoxia, respectively. Novel molecular strategies designed to interfere with the activities of these gene products are being devised as ways to overcome the physiologic barriers in the tumor to standard anticancer therapies. (Mol Cancer Res 2006;4(2):61–70)
Prevalence of Typus Melancholicus in Healthy Germans
Authors: Ueki Hirofumi , Holzapfel Christian , Sakado Kaoru , Washino Kaei , Inoue Masato , Ogawa Naoshi , Ietsugu Tetsuji , Takai Akihiro
Published: March 2006

Background: There have been few studies concerning the prevalence of Typus melancholicus (TM) in healthy volunteers based on age or sex. To our knowledge, no such studies have been performed in healthy Germans, but several in healthy Japanese people. Therefore, it is necessary to also determine the prevalence of TM in healthy Germans, in order to know whether the prevalence of TM is cross-culturally constant. Subjects and Methods: We examined the prevalence of TM in 121 healthy German volunteers (62 men and 59 women with a mean age ± SD of 43.9 ± 16.8 years and 47.4 ± 15.9 years, respectively). Kasahara’s Inventory for the Melancholic Type Personality (KIMTP) and von Zerssen’s F-List (F-List) were used to identify TM. The subjects were divided by age into three groups: those aged 40 years or less (group A), those aged 41–60 years (group B), and those aged 61 years or more (group C). Mean total KIMTP and F-List scores were calculated. In addition, we also calculated mean scores of the two KIMTP TM factors [‘harmony in personal relationships’ (factor 1) and ‘social norms’ (factor 2)]. Differences in scores between men and women were analyzed by Student’s t test. Differences in scores between the three age groups were evaluated by one-way analysis of variance and Scheffé’s test. Results: The KIMTP and F-List scores increased with age in both men and women. In the women, the KIMTP and F-List scores were significantly higher in groups B and C than in group A. In the women, the group C KIMTP factor 1 score was significantly higher than the group A KIMTP factor 1 score. The KIMTP and F-List scores tended to be higher for the women than for the men. Within groups B and C, the KIMTP and F-List scores and the KIMTP factor 1 score were significantly higher for the women than for the men. Conclusion: Overall, the sex and age distributions of scores for both questionnaires were similar to those obtained in previous studies in Japanese people. It is of note that our German subjects and previous Japanese subjects were not demographically controlled and, clearly, cultural backgrounds differed. Thus, KIMTP and the F-List may discriminate the TM personality with some degree of universality despite cultural differences and might be useful in cross-cultural comparisons of TM.
Persistent Auditory Hallucinations
Authors: González J.C. , Aguilar E.J. , Berenguer V. , Leal C. , Sanjuan J.
Published: March 2006

Background: There is still a significant proportion of psychotic patients who suffer from persistent auditory hallucinations (PAH) in spite of treatment. The objective of our study was to analyze those clinical dimensions that characterize persistent hallucinators in comparison with episodic hallucinators. Sampling and Methods: Ninety-one outpatients with AH were assessed through semistructured interviews. The interviews included the Psychotic Symptom Rating Scales for AH and the Krawiecka scale. They elicited descriptions about the persistence of AH, existence of pleasurable hallucinations and other types of hallucinations. Results: Forty-five patients fulfilled criteria for reported PAH. Persistent hallucinators showed greater scores in frequency and duration of hallucinations, Krawiecka total score and incoherence of speech. Moreover, pleasurable experiences were more frequent in this group of patients. Logistic regression analysis rendered a model with the following variables: duration of voices, degree of control and pleasurable hallucinations. Conclusion: Specific dimensions of AH can predict the possibility of treatment resistance.
Body Dysmorphic Disorder, Psychosis and Insight: A Report of Four Cases
Authors: Lucchelli Juan Pablo , Bondolfi Guido , Bertschy Gilles
Published: March 2006

Body dysmorphic disorder is described in the DSM-IV as a single clinical entity, but an additional diagnosis of delusional disorder, somatic type, is allowed when the preoccupation concerning an imaginary defect in appearance is held with delusional intensity. The existence of two clinical forms is implicitly recognized, depending on the presence or absence of psychotic symptoms. Several studies have suggested that these two forms make up a single illness, characterized by different degrees of insight. This supposition is supported by the fact that the symptomatology and the clinical response to the SSRIs are thought to be similar for the two forms. Moreover, certain authors have suggested that categorical nosography (as used by the DSM-IV) should not be the point of reference and that a ‘dimensional’ point of view is preferable, meaning that the presence of psychotic symptoms would constitute merely a simple phenomenon or state of the same illness.
Medical Termination of Pregnancy in Acute Intermittent Porphyria
Authors: Sahu Meenakshi T. , Rajaram Shalini , Saxena Ashok Kumar , Goel Neerja , Ghumman Surveen
Published: March 2006

Acute intermittent porphyria is a rare autosomal dominant disease characterized by acute attacks of neuropsychiatric and neurovisceral dysfunction. In pregnancy, exacerbation of attacks in the form of seizures and acute abdomen occur due to hormonal changes. We report the case of a young woman presenting at 8 weeks of gestation requesting pregnancy termination. The patient suffered several episodes of acute abdomen and seizures in a prior pregnancy before the diagnosis was clinched. This case is reported because of its rarity and the limited obstetric experience of this disorder. Proper management depends on avoidance of precipitating factors. Anaesthetic drug safety in porphyria is reviewed and the choice of regional anaesthesia discussed
Angiotensin-Converting Enzyme II in the Heart and the Kidney
Authors: Danilczyk Ursula , Penninger Josef M.
Published: March 2006

The renin-angiotensin system (RAS) has been recognized for many years as critical pathway for blood pressure control and kidney functions. Although most of the well-known cardiovascular and renal effects of RAS are attributed to angiotensin-converting enzyme (ACE), much less is known about the function of ACE2. Experiments using genetically modified mice and inhibitor studies have shown that ACE2 counterbalances the functions of ACE and that the balance between these two proteases determines local and systemic levels of RAS peptides such as angiotensin II and angiotensin1–7.Ace2mutant mice exhibit progressive impairment of heart contractility at advanced ages, a phenotype that can be reverted by loss of ACE, suggesting that these enzymes directly control heart function. Moreover, ACE2 is also found to be upregulated in failing hearts. In the kidney, ACE2 protein levels are significantly decreased in hypertensive rats, suggesting a negative regulatory role of ACE2 in blood pressure control. Moreover, ACE2 expression is downregulated in the kidneys of diabetic and pregnant rats and ACE2 mutant mice develop late onset glomerulonephritis resembling diabetic nephropathy. Importantly, ACE2 not only controls angiotensin II levels but functions as a protease on additional molecular targets that could contribute to the observed in vivo phenotypes of ACE2 mutant mice. Thus, ACE2 seems to be a molecule that has protective roles in heart and kidney. The development of drugs that could activate ACE2 function would allow extending our treatment options in diabetic nephropathy, heart failure, or hypertension.
Electrocardiogram in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy Patients Without Any Clinical Evidence of Coronary Artery Disease
Authors: Cumurciuc Rodica , Henry Patrick , Gobron Claire , Vicaut Eric , Bousser Marie-Germaine , Chabriat Hugues , Vahedi Katayoun
Published: March 2006

Background and Purpose—

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited systemic arteriopathy caused by highly stereotyped mutations in
NOTCH3
. The clinical expression of CADASIL is confined to the central nervous system with characteristic recurrent subcortical infarcts and vascular dementia. However, cases have been reported with associated circulatory small vessel abnormalities in the retina or the myocardium and with myocardial infarction. Classical cardiovascular risk factors may influence such circulatory abnormalities. Thus, we conducted a case control study to determine the frequency of electrical abnormalities on a 12-lead resting ECG in CADASIL patients without classical atherosclerotic risk factors.

Methods—

Twenty-three CADASIL patients (mean age±SD; 55.1±11 years) free of any classical cardiovascular risk factors except for hypercholesterolemia were recruited from 1 neurology department and compared with 23 sex- and age-matched healthy controls (mean age±SD; 54.7±9.5 years). A resting supine 12-lead ECG was recorded at inclusion and analyzed later by 2 reviewers. Signs of myocardial infarction or ischemia, conduction, and rhythm disturbances were looked for.

Results—

We found no ECG sign evoking myocardial infarction or myocardial ischemia. CADASIL patients had, compared with healthy controls, a significantly higher heart rate and a significantly lower Sokolow index, but these values remained in the normal ranges.

Conclusions—

In this case-control study, we found no ECG evidence for myocardial infarction or ischemia, conduction disturbances, or arrhythmias in CADASIL patients compared with healthy controls.
The Use of Embolic Signal Detection in Multicenter Trials to Evaluate Antiplatelet Efficacy
Authors: Dittrich Ralf , Ritter Martin A. , Kaps Manfred , Siebler Mario , Lees Kennedy , Larrue Vincent , Nabavi Darius G. , Ringelstein E. Bernd , Markus Hugh S. , Droste Dirk W.
Published: March 2006

Background and Purpose—

The CARESS (Clopidogrel and Aspirin for Reduction of Emboli in Symptomatic carotid Stenosis) trial proved the effectiveness of the combination of clopidogrel and aspirin compared with aspirin alone in reducing presence and number of microembolic signals (MES) in patients with recently symptomatic carotid stenosis. The present study aimed at installing primary and secondary quality control measures in CARESS because MES evaluation relies on subjective judgment by human experts.

Methods—

As primary quality control, centers participating in CARESS evaluated a reference digital audio tape (DAT) before the study containing both MES and artifacts. Interobserver agreement of classifying signals as MES was expressed as proportions of specific agreement of positive ratings (ps±values). For all DATs included in CARESS (n=300), online number of MES and off-line number of MES read by the central reader were compared using correlation coefficients. As secondary control, a sample of 16 of 300 DATs was cross-validated by another independent reader (post-trial validator).

Results—

For the reference tape, the cumulative ps±value was 0.894 based on 12 of 14 observers. Two observers with very different results improved after a training procedure. Agreement between post-trial validator and central reader was ps+=0.805, indicating very good agreement. Correlation between online evaluation and off-line evaluation of DATs was very good overall (cumulative ρ=0.84;
P
<0.001).

Conclusion—

Multicenter studies using MES as outcome parameter are feasible. However, primary and secondary quality control procedures are important.
Negotiating to Control Weapons of Mass Destruction in North Korea
Authors: Clemens Walter
Published: March 2006

Negotiations to control and perhaps eliminate North Korea's weapons of mass destruction (WMD) appeared to achieve positive results in the 1990s. But these positive trends reversed direction in 2001–2004 under President George W. Bush. Why? This essay weighs six possible explanations. 1. progress in the 1990s as a mirage; 2. cultural differences; 3. distrust of international agreements; 4. perceptions regarding the utility of WMD; 5. internal divisions within each government and society; and 6. ulterior motives.The evidence suggests that the sixth explanation carries the most weight. Top leaders in the Democratic People's Republic of Korea (DPRK) as well as in the United States had priorities other than arms control. Each side used arms control negotiations as an instrument to promote its political and economic agenda in other realms. Pyongyang demanded large and certain rewards to give up its main bargaining chips. North Korea's negotiating behavior suggested some willingness to freeze or eliminate WMD programs if the price were right. But Kim Jong Il's regime clearly saw its nuclear and missile capabilities as major assets not to be traded away except for very substantial security and economic rewards. For its part, the Bush White House probably worried that any accord with Pyongyang would impede Washington's larger political, military, and economic ambitions, including deployment of a national missile defense (NMD). There was also a subjective element: President Bush probably loathed Kim Jong Il and did not relish the prospect of making any compromises with evil incarnate. For enlightened self-interest to prevail, the parties could benefit from greater empathy and a quest for mutual rather than one-sided gain.
From Individual State Preferences to Collective Decisions: An Analytic Account of the 1995 NPT Review and Extension Conference
Authors: Essis Essoh
Published: March 2006

This article provides a framework for the analysis of the Non-Proliferation Treaty's five-year review conferences and of similar multilateral collective security policy-making fora from a truly global perspective. Factor and discriminant analytic models have made it possible to broaden the scope of inquiry beyond the interests, capabilities and preferences of the few rich and powerful states. Additionally, the use of participant observation, historical analysis and legal hermeneutics techniques provides a much needed qualitative perspective that complements and refines the interpretation of quantitative findings.
Dynamical Processes of Equatorial Atmospheric Angular Momentum
Authors: Feldstein Steven B.
Published: March 2006

The dynamical processes that drive intraseasonal equatorial atmospheric angular momentum (EAAM) fluctuations are examined with the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis data. The primary methodology involves the regression of relevant variables including the equatorial bulge, mountain, and friction torques, surface pressure, streamfunction, and outgoing longwave radiation, against the time derivative of the two components and the amplitude of the EAAM vector.

The results indicate that the observed 10-day westward rotation of the EAAM vector corresponds to the propagation of a zonal wavenumber-1, antisymmetric, Rossby wave normal mode. Additional findings suggest that fluctuations in the amplitude of the EAAM vector are driven by poleward-propagating Rossby waves excited by the latent heating within equatorial mixed Rossby–gravity waves and also by wave–wave interaction among planetary waves. Both of these processes can induce surface pressure anomalies that amplify the EAAM vector via the equatorial bulge torque. The Antarctic and Greenland mountain torques were found to drive large fluctuations in the amplitude of the EAAM vector. Both the friction torque and wave–zonal-mean flow interaction were shown to dampen the EAAM amplitude fluctuations.

A comparison of the EAAM dynamics in the atmosphere with that in an aquaplanet GCM suggests that the mountain torque also drives fluctuations in the phase speed of the atmospheric wave field associated with the EAAM vector, and it confines the wave–wave interaction to planetary scales.
A Theory of Gravity Wave Absorption by a Boundary Layer
Authors: Smith Ronald B. , Jiang Qingfang , Doyle James D.
Published: March 2006

A one-layer model of the atmospheric boundary layer (BL) is proposed to explain the nature of lee-wave attenuation and gravity wave absorption seen in numerical simulations. Two complex coefficients are defined: the compliance coefficient and the wave reflection coefficient. A real-valued ratio of reflected to incident wave energy is also useful. The key result is that, due to horizontal friction, the wind response in the BL is shifted upstream compared to the phase of disturbances in the free atmosphere. The associated flow divergence modulates the thickness of the BL so that it partially absorbs incident gravity waves. A simple expression is derived relating the reflection coefficient to the attenuation and wavelength shift of trapped lee waves. Results agree qualitatively with the numerical simulations, including the effects of increased surface roughness and heat flux.
Low-Order Stochastic Mode Reduction for a Prototype Atmospheric GCM
Authors: Franzke Christian , Majda Andrew J.
Published: March 2006

This study applies a systematic strategy for stochastic modeling of atmospheric low-frequency variability to a three-layer quasigeostrophic model. This model climate has reasonable approximations of the North Atlantic Oscillation (NAO) and Pacific–North America (PNA) patterns. The systematic strategy consists first of the identification of slowly evolving climate modes and faster evolving nonclimate modes by use of an empirical orthogonal function (EOF) decomposition in the total energy metric. The low-order stochastic climate model predicts the evolution of these climate modes a priori without any regression fitting of the resolved modes. The systematic stochastic mode reduction strategy determines all correction terms and noises with minimal regression fitting of the variances and correlation times of the unresolved modes. These correction terms and noises account for the neglected interactions between the resolved climate modes and the unresolved nonclimate modes. Low-order stochastic models with 10 or less resolved modes capture the statistics of the original model very well, including the variances and temporal correlations with high pattern correlations of the transient eddy fluxes. A budget analysis establishes that the low-order stochastic models are highly nonlinear with significant contributions from both additive and multiplicative noise. This is in contrast to previous stochastic modeling studies. These studies a priori assume a linear model with additive noise and regression fit the resolved modes. The multiplicative noise comes from the advection of the resolved modes by the unresolved modes. The most straightforward low-order stochastic climate models experience climate drift that stems from the bare truncation dynamics. Even though the geographic correlation of the transient eddy fluxes is high, they are underestimated by a factor of about 2 in the a priori procedure and thus cannot completely overcome the large climate drift in the bare truncation. Also, variants of the reduced stochastic modeling procedure that experience no climate drift with good predictions of both the variances and time correlations are discussed. These reduced models without climate drift are developed by slowing down the dynamics of the bare truncation compared with the interactions with the unresolved modes and yield a minimal two-parameter regression fitting strategy for the climate modes. This study points to the need for better optimal basis functions that optimally capture the essential slow dynamics of the system to obtain further improvements for the reduced stochastic modeling procedure.
Effective Refractive Indices of Water and Sulfate Drops Containing Absorbing Inclusions
Authors: Erlick Carynelisa
Published: March 2006

In this study the range of visible refractive indices and single-scattering albedos that can be obtained using various mean field formulations for mixtures of two components, where one component absorbs in the visible, is explored. For calculations of global radiative forcing and climate response, such formulations provide a convenient way to take into account internal mixing of aerosol components without the computational burden of a more exact theory, provided that the limits of their applicability are kept in mind. Within those limits, the results show that for water and sulfate drops containing dust and soot inclusions, the degree of interaction between the electric fields of neighboring inclusions is not important. However, the shape and size of the inclusions can cause a variation in the effective imaginary refractive index of up to a factor of 3.4 and a variation in the single-scattering albedo of up to 0.18 in absolute value.
Empirically Evaluating Divergence Rates of Atmospheric Trajectories
Authors: Eshel Gidon
Published: March 2006

Observed Northern Hemisphere divergence rates of phase-space trajectories initially emanating from neighboring points are estimated, using a simple, seasonal, weakly GCM-dependent linear method applied to Ertel potential vorticity on the 315-K isentrope. Using the same data and essentially the same method, atmospheric persistence, the rate of trajectory departure from an initial state, is also estimated. With the results applying only to the truncated state considered (comprising only a single variable observed at a single level), it is found that the time scale for divergence of two, initially reasonably similar, trajectories is about 4–6 days, between the time scales of cyclogenesis and blocking. It is also found that the time scale for divergence of a given trajectory from an earlier point along it is about 3–5 days.
Conditions That Inhibit the Spontaneous Radiation of Spiral Inertia–Gravity Waves from an Intense Mesoscale Cyclone
Authors: Schecter David A. , Montgomery Michael T.
Published: March 2006

The spontaneous radiation of spiral inertia–gravity (IG) waves from monotonic cyclones is reexamined. Such radiation can occur most significantly in a parameter regime that includes strong supercell mesocyclones and hurricanes. First, linear theory is reviewed. In linear theory, a generic deformation of the cyclone excites discrete vortex Rossby (VR) waves. Each VR wave emits a frequency-matched spiral IG wave into the environment. The emission has positive feedback on the VR wave, causing both to grow. However, the VR wave also deposits wave activity into its critical layer at the radius r*. If the radial gradient of potential vorticity at r* exceeds a threshold, critical layer absorption suppresses the radiative instability.

On the other hand, numerical simulations of a shallow-water cyclone show that nonlinear changes to the critical layer can revive a damped VR wave and its radiation field after a brief period of decay. For such revival, it suffices that Ωb/|γ| ≳ 1. This inequality contains two characteristic frequencies. The denominator |γ| is the absolute value of the (negative) growth rate of the damped wave. The numerator Ωb is the mixing rate of the critical layer, which is proportional to the square root of the initial wave amplitude.

After damping is reversed, the radiative VR wave exhibits undulatory growth. Analysis shows that growth proceeds because radiation steadily removes negative wave activity from the cyclone. Secondary amplitude oscillations are due to back-and-forth exchanges of positive wave activity between the VR wave and its critical layer.
Variability of the Southern Hemisphere Winter Split Flow—A Case of Two-Way Reinforcement between Mean Flow and Eddy Anomalies
Authors: Yang Xiaosong , Chang Edmund K. M.
Published: March 2006

A new split-jet index is defined in this study, and composites based on this index show that the split-flow regime is characterized by a cold–warm–cold tripolar temperature anomaly in the South Pacific that extends equatorward from the Southern Hemisphere (SH) high latitudes, while nonsplit flow occurs when the phase of the tripolar temperature anomaly is reversed. Analyses of the heat budget reveal that the temperature anomalies associated with the split/nonsplit flow are mainly forced by mean flow advection instead of local diabatic heating or convergence of eddy heat fluxes. Localized Eliassen–Palm (E–P) flux diagnostics suggest that the zonal wind anomalies are maintained by the eddy vorticity flux anomalies.

These diagnostic results are confirmed by numerical experiments conducted using a stationary wave model forced by observed eddy forcings and diabatic heating anomalies. The model results show that the effects of the vorticity flux dominates over those of the heat flux, which tend to dampen the flow anomalies, and that tropical diabatic heating anomalies are not important in maintaining the split-/nonsplit-flow anomalies.

The organization of high-frequency eddies by the low-frequency split/nonsplit jet is also studied. Two sets of experiments using a linear storm-track model initialized with random initial perturbations superposed upon the split- and nonsplit-jet basic state, respectively, have been conducted. Model results show that the storm-track anomalies that are organized by the split/nonsplit jet are consistent with observed storm-track anomalies, thus demonstrating that the low-frequency split/nonsplit jet acts to organize the high-frequency eddies.

The results of this paper directly establish that there is a two-way reinforcement between eddies and mean flow anomalies in the low-frequency variability of the SH winter split jet.
On the Application of the Dynamic Smagorinsky Model to Large-Eddy Simulations of the Cloud-Topped Atmospheric Boundary Layer
Authors: Kirkpatrick M. P. , Ackerman A. S. , Stevens D. E. , Mansour N. N.
Published: March 2006

In this paper the dynamic Smagorinsky model originally developed for engineering flows is adapted for simulations of the cloud-topped atmospheric boundary layer in which an anelastic form of the governing equations is used. The adapted model accounts for local buoyancy sources, vertical density stratification, and poor resolution close to the surface and calculates additional model coefficients for the subgrid-scale fluxes of potential temperature and total water mixing ratio. Results obtained with the dynamic model are compared with those obtained using two nondynamic models for simulations of a nocturnal marine stratocumulus cloud deck observed during the first research flight of the second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field experiment. The dynamic Smagorinsky model is found to give better agreement with the observations for all parameters and statistics. The dynamic model also gives improved spatial convergence and resolution independence over the nondynamic models. The good results obtained with the dynamic model appear to be due primarily to the fact that it calculates minimal subgrid-scale fluxes at the inversion. Based on other results in the literature, it is suggested that entrainment in the DYCOMS-II case is due predominantly to isolated mixing events associated with overturning internal waves. While the behavior of the dynamic model is consistent with this entrainment mechanism, a similar tendency to switch off subgrid-scale fluxes at an interface is also observed in a case in which gradient transport by small-scale eddies has been found to be important. This indicates that there may be problems associated with the application of the dynamic model close to flow interfaces. One issue here involves the plane-averaging procedure used to stabilize the model, which is not justified when the averaging plane intersects a deforming interface. More fundamental, however, is that the behavior may be due to insufficient resolution in this region of the flow. The implications of this are discussed with reference to both dynamic and nondynamic subgrid-scale models, and a new approach to turbulence modeling for large-eddy simulations is proposed.
Development of a Detailed Microphysics Cirrus Model Tracking Aerosol Particles’ Histories for Interpretation of the Recent INCA Campaign
Authors: Monier Marie , Wobrock Wolfram , Gayet Jean-François , Flossmann Andrea
Published: March 2006

Cirrus clouds play an important role in the earth’s energy balance. To quantify their impact, information is needed on their microstructure and more precisely on the number and size of the ice crystals. With the anthropogenic activity, more and more aerosol particles and water vapor are released even at the altitude where cirrus clouds are formed. Cirrus clouds formed in a polluted air mass may have different microphysical properties and, therefore, a different impact on the climate system via the changed radiative properties compared to background cirrus clouds. To study this aspect, the European project called the Interhemispheric Differences in Cirrus Properties due to Anthropogenic Emissions (INCA) measured the microphysical properties of cirrus clouds together with the physical and chemicals properties of aerosol particles in clean air (at Punta Arenas, Chile) and polluted air (at Prestwick, Scotland). The goal of the present work was to develop a detailed microphysics model for cirrus clouds for the interpretation and the generalization of the INCA observations. This model considers moist aerosol particles through the Externally Mixed (EXMIX) model, so that the chemical composition of solution droplets can be followed. Ice crystal formation is described through homogeneous or heterogeneous nucleation. The crystals then grow by deposition. With this model, the interactions between the microphysical processes, simulated ice crystal concentrations, and dimensional distributions of the INCA observations were studied, and explanations were provided for the observed differences between background and polluted cirrus clouds.
Cloud Phase Structure: Experimental Data Analysis and Parameterization
Authors: Mazin I. P.
Published: March 2006

In this article, the data collected over 6 yr of daily observations at a network of aircraft sounding (31 stations) in the former Soviet Union, and the data collected by Canadian researchers in field campaigns in the 1990s, are reanalyzed and compared with each other. To describe the cloud phase structure (CPS), the notion of the cloud phase index (CPI)3 is used; that is, the local mass fraction of the ice particles in the total (water + ice) water content. It is concluded that the average distribution of the (CPI)3 values in clouds depends mainly on the temperature, the cloud types, and the scale of averaging. If these characteristics remain unchanged the geographic and seasonal variations of the phase structure are small. It is shown that for averaging scales of the order of 100 m, the frequency of occurrence of liquid clouds [(CPI)3 = 0] varies from approximately 60% at 0°C to 5% at −35°C, and that of the ice clouds from about 5% to 60%. The frequency of occurrence of the mixed clouds only weakly depends on temperature, varying within 30%–40%. The dependence of the cumulative (CPI)3 distribution on temperature in the interval 0.1 < (CPI)3 < 0.7 is close to linear. For stratiform clouds (without going into further details) the coefficients of the linear parameterization are found as a function of temperature. Knowing the (CPI)3 distribution allows one to also estimate the humidity in clouds. The most urgent challenges for the experimental studies of the cloud phase structure are formulated.
A Dialectical Approach to Formulating and Testing Social Science Theories: Assumptional Analysis
Authors: Kilmann Ralph H.
Published: March 2006

It is argued that the necessary step in the formulation of “good” theories and their subsequent testing and refinement is uncovering the relevant underlying assumptions that different scientists make concerning the nature of human behavior, social environments, and the interactions between these. Since assumptions are, by definition, implicit, unconscious, or even obscure, an explicit process is needed to examine this hidden domain. This paper presents such a process and illustrates how this dialectical approach can be utilized to facilitate advances in social science research.
Back-Home Environment and Within-Group Relationships as Determinants of Personal Change
Authors: Smith Peter B.
Published: March 2006

The persistence of change after 1-week sensitivity training groups was studied, using data from 163 British and American trainees. An own-control design was used, in which subjects evaluated change occurring prior to training and five months later. Two criteria of change were employed: subjects' evaluation of their own change, and evaluations of changes in their six most salient relationships. Subjects were also asked to characterize those who most influenced them both within the' group and in back-home settings. The persistence of change was found to be best predicted neither by the quality of relationships within the group, nor by back-home relationships, but by the degree of matching between the two environments. Own-benefit scores were greatest with high matching, whereas relationship-benefit scores were higher where the two environments contrasted. It is concluded that theories of personal change must take greater note of the relation between the T-group setting and the back-home environment than has thus far been the case.
Research-Based Projects as a Learning Strategy in Business Schools
Authors: Joynt Pat
Published: March 2006

This article presents a summary of a new learning strategy for practicing managers who attend courses in business schools. Experimental experiential learning combines the research process (experimentation) with the practical managers' everyday life (experiences in organization behavior). The theoretical foundations are reviewed in the first section, followed by a short presentation of the experimental model used in a specific management course. The result has been the formulation of more complex theories of administration, namely contingency theories. Finally, the experimental experiential strategy is compared with the more universal textbook-exam strategies, and the author suggests that this type of learning strategy may help to close the gap between the researcher and the practicing manager.
Cohesion as a Basic Bond in Groups
Authors: Piper William E. , Marrache Myriam , Lacroix Renee , Richardsen Astrid M. , Jones Barry D.
Published: March 2006

Cohesion continues to remain a popular concept among group therapists and leaders of experientially based learning groups despite persistent confusion about its meaning. The present study provided an empirical basis for clarification of the concept of cohesion. Forty-five participants from nine experientially based learning groups provided self-report and behavioral data concerning a number of aspects of cohesion. Factor analyses of the self-report data generated three sets of factors that dealt with the participant's perception of the other participants, the leader, and the group as a whole. One of the factors concerned the participant's commitment to the group. It was significantly related to remaining in the group and physical distance to others but not to perceptions of learning. It was regarded as a good representation of cohesion as defined as a basic bond or uniting force in a group. The advantages of restricting oneself to a circumscribed definition of cohesion were emphasized as well as maintaining distinctions between cohesion and other concepts.