bluuebunny/crossref_metadata_2025 huggingface dataset:
Note on the holographic c‐function
Authors: Miemiec A.
Published: March 2004

We discuss the holographic c‐function and describe an algorithm for the practical computation of the changing central charge in arbitrary RG‐flows. The conclusions are drawn from studying a particular example, which is worked out in detail. The renormalisation procedure of hep‐th/0112150 necessary to obtain the central charge is reviewed.
Quantization of the optical phase space 𝒮2 = {ϕ mod 2π, I > 0} in terms of the group SO↑(1, 2)
Authors: Kastrup H.A.
Published: March 2004

For a considerably expanded Chap. 4 (Harm. osc.) and additional references see e‐print archives quant‐ph/0307069.
Genetic Basis of Congenital Nephrotic Syndrome
Authors: Finn Laura S.
Published: March 2004

A young girl presented at 1 month of age with nephrotic syndrome. By incorporating clinical and pathologic data, the diagnosis of congenital nephrotic syndrome, Finnish type, was made. The differential diagnosis of early onset nephrotic syndrome, as it pertains to this patient is discussed. This article highlights recently discovered glomerular filtration proteins and their relationship to the pathophysiology of inherited kidney disease.
Well-Differentiated Fetal Adenocarcinoma: Rare Tumor in the Pediatric Population
Authors: DiFurio Megan J. , Auerbach Aaron , Kaplan Keith J.
Published: March 2004

Well-differentiated fetal adenocarcinoma (WDFA) is a rare tumor of the lung, which has gone by many names over the years. The lesion was first described by Kradin et al., in 1982, who called it “pulmonary blastoma with argyrophil cells and lacking sarcomatous features (pulmonary endodermal tumor resembling fetal lung).” Since then, there have been at least 65 cases reported in the literature. Although there has been no consensus in the literature as to the best pathological term for this entity, the most recent World Health Organization classification of lung and pleural tumors uses the term well-differentiated fetal adenocarcinoma. Characteristically, this lesion consists of an epithelium, which recapitulates fetal lung at 3–5 months of gestation and demonstrates neuroendocrine differentiation. Although the classic age range is 30–40 years, there have been seven reports of WDFA in the pediatric age. We report an additional pediatric case of this tumor and review the pediatric cases in the existing literature.
A simple criterion for successful biological control on annual crops
Authors: Urano Satoru , Shima Katsuya , Hongo Koichi , Suzuki Yoshito
Published: March 2004

Population dynamics of pest insect‐natural enemy systems on annual crops is quite different from those seen in classic biological control programes. On an annual crop, for example, the persistence of populations of pest insects is forced to terminate when crops are harvested. Pest control on annual crops aims to suppress the maximum density of the pest below a certain level, and a low level equilibrium is not always the aim. It is important to determine the initial impact just after release of a natural enemy in order to determine the success of a biological control program. Therefore, effectiveness of natural enemies should be evaluated by prediction of such short‐term population dynamics. This paper presents a new and simple analytical model for successful biological control on annual crops. A criterion of successful biological control is given as the ratio of the pest and natural enemy populations just when the pest begins to decrease. This ratio is derived from the intrinsic rates of natural increase of both populations and the daily total predation by natural enemies. Using this model, criteria on appropriate number and time of release of natural enemies are obtained. The practical applications of this model are discussed with respect to evaluating the success or failure of natural enemy releases in future biological control programs.
Dispersal patterns of endemic alpine butterflies with contrasting population structures:Erebia epiphronandE. sudetica
Authors: Kuras Tomas , Benes Jiri , Fric Zdenek , Konvicka Martin
Published: March 2004

We studied population sizes and mobility ofErebia epiphronandErebia sudetica, two high mountain butterflies forming endemic subspecies in the Hrubý Jeseník Mountains, Czech Republic.E. epiphronformed two continuous populations containing ≈100,000 and ≈4,500 individuals on alpine grasslands. The butterflies moved freely within their habitats, but movements between the two populations were highly unlikely.E. sudeticaformed a system of colonies at timberline sites on valley headwalls and in forest clearings. Two such colonies studied in detail contained ≈4,500 and ≈450 adults and were interconnected by limited dispersal. The negative exponential function and the sigmoid function (this assumes flat decrease of movements over short distances) were superior to the inverse power function in fitting mobility data for both species. ForE. sudetica, the functions describing movements within a habitat differed significantly from total movements, suggesting different behaviours of dispersing individuals. The habitats ofE. epiphronare uniform and highly isolated, favouring free within‐habitat mobility but prohibiting leaving their boundaries. The habitats ofE. sudeticaare diverse and disturbance‐dependent; leaving such habitats is less risky, and a source‐sink model may explain the persistence of the species in the mountains.
Estimation of dispersal distance by mark‐recapture experiments using traps: correction of bias caused by the artificial removal by traps
Authors: Yamamura Kohji , Kishita Mitsunobu , Arakaki Norio , Kawamura Futoshi , Sadoyama Yasutsune
Published: March 2004

Although in mark‐recapture experiments traps are useful to estimate the dispersal distance of organisms, they cause a dilemma that may be called a kind of Heisenberg effect: a large number of traps should be placed to yield a precise estimate of mean dispersal distance, while these traps shorten the mean dispersal distance itself by intercepting organisms that should have dispersed for further distances. We propose a procedure to solve this dilemma by placing traps uniformly in a lattice pattern, and by assuming a random movement and a constant rate of settlement for organisms. We applied this procedure to estimate the dispersal distance of the sugarcane wirewormMelanotus okinawensisOhira (Coleoptera: Elateridae). The estimated mean dispersal distance was 143.8 m. Through the use of a conventional method of estimation, the mean dispersal distance was estimated to be 118.1 m. Thus, it was shown that the conventional estimate of dispersal distance was 18% smaller than the corrected estimate in our experiment.
Radiation and reticulation: extensive introgressive hybridization in the carabid beetles Ohomopterus inferred from mitochondrial gene genealogy
Authors: Sota T.
Published: March 2004

In the evolutionary process of an animal lineage, interactions in secondary contacts of differentiated populations and introgressive hybridization may play an important role. In the Japanese islands, the carabid subgenus Ohomopterus (genus Carabus) exhibits a marked differentiation in body size and genital morphology. Although geographical differentiation is apparent, two or three species usually coexist at many localities. Their reproductive isolation relies on body size differences, chemical cues for mate recognition, and a species‐specific genital lock‐and‐key system. However, these isolation mechanisms are not always effective enough to prevent interspecific hybridization. An initial assessment of the species‐level phylogeny with mitochondrial gene sequences revealed that the gene genealogy is highly inconsistent with the morphology‐based taxonomy. A comparison of mitochondrial and nuclear gene genealogies showed that these are strongly incongruent with each other, while the nuclear gene genealogy is more consistent with traditional taxonomy, indicating the repeated occurrence of introgression of mitochondria across species. Here, two different cases of mitochondrial introgression among Ohomopterus species are described in detail, one for parapatric species and the other for sympatric species. First, mitochondrial haplotypes and sequences were studied in Carabus insulicola and three taxa parapatric with C. insulicola, at least two of which hybridize with C. insulicola naturally. Among the four species studied, directional introgressions of mitochondria across boundary zones were detected. Second, in the Mt. Kongo area in central Honshu, which harbors five species, introgression of mitochondria among four out of the five species was detected, despite the apparent absence of on‐going natural hybridization. These inferred cases of mitochondrial introgression indicate that species interactions through hybridization could have played an important role at various stages in the evolution of Ohomopterus.
Modeling species richness controlled by community‐intrinsic and community‐extrinsic processes: coastal fish communities as an example
Authors: Stenseth N. C. , Lekve K. , Gjøsæter J.
Published: March 2004

This article focuses on the analysis of coastal fish communities along the Norwegian Skagerrak coast. Species numbers are estimated based on annual samples of the fish communities within 12 fjords from 1953 to 1994. On this basis, a community dynamics model (incorporating both community‐intrinsic and community‐extrinsic processes) was developed and analyzed. This model is then discussed on the basis of other community models available through the literature, both phenomenologically oriented and process‐oriented models.
Indeterminate growth is selected by a trade‐off between high fecundity and risk avoidance in stochastic environments
Authors: Katsukawa Y. , Katsukawa T. , Matsuda H.
Published: March 2004

We developed a stage‐structured model to describe optimal energy allocation among growth, reproduction, and survival. Our model includes stochastic fluctuations in survival rate at age 0 but constant survival rate at older ages. Many mammals and birds cease to grow after maturity (i.e., determinate growth), whereas organisms in a number of other taxa grow beyond maturation (i.e., indeterminate growth). We discuss the conditions under which each of the following strategies is optimal: (I) semelparity, (II) iteroparity with determinate growth, and (III) iteroparity with indeterminate growth. Our model demonstrates that iteroparity with indeterminate growth is selected for when a nonlinear relationship exists between weight and energy production; this strategy is also often selected for in stochastic environments, even with a linear relationship between weight and energy production. The optimal strategy in stochastic environments is to maximize the long‐term population growth rate, which does not correspond with maximization of total fecundity. The optimal life history is determined by a balance between spreading a risk and increasing the number of offspring. Our model suggests that optimal life history strategy depends on the magnitude of environmental fluctuations, the advantage of investing in growth, the cost of survival, and the nonlinearity between weight and energy production.
Evolution of apomixis as a strategy of colonization in the dioecious species Lindera glauca (Lauraceae)
Authors: Dupont Y. L.
Published: March 2004

I have investigated the reproductive biology of four dioecious species of Lindera in Japan: Lindera obtusiloba Bl., L. umbellata Thunb., L. erythrocarpa Makino, and L. glauca Bl. The sex ratios in populations of the first three species are close to equality, but in L. glauca only female individuals are found in Japan, although males are known from continental Asia. The persistence of this dioecious species in the absence of males is surprising, and prompts the question: What mechanisms operate to ameliorate problems of colonization in species of Lindera? I carried out bagging experiments in order to test for apomixis (asexual reproduction by seeds) and to establish the importance of pollination and fertilization, and potential pollen vectors. Only L. glauca reproduced by apomixis. Level of fruit set was high, and was not affected by pollination. In the other three species, seed set was entirely dependent on pollen transfer, which could be accomplished by small Coleoptera and Diptera. The evolution of apomixis in L. glauca appears to have been a strategy to overcome sterility and establish a population in the Japanese islands even in the absence of males. However, this change in breeding system has not occurred in congeneric, co‐occurring species, which do not seem to have experienced a lack of male plants.
Differentiation of chromaffin cells elicited by ELF MF modifies gene expression pattern
Authors: Olivares‐Bañuelos Tatiana , Navarro Luz , González Alicia , Drucker‐Colın Rene
Published: March 2004

Chromaffin cells exposed to extremely low frequency magnetic fields (ELF MF, 60 Hz, 0.7 mT) differentiate into sympathetic neuron‐like cells. This complex process must involve both qualitative and quantitative variations in gene expression. This study looks at whether ELF MF treatment provokes changes in the global transcription profile of chromaffin cells, using the RT‐Differential Display method. When the gene expression patterns of experimental groups (nerve growth factor (NGF) and ELF MF) were compared to those receiving no treatment, at least 53 transcripts showing differential expression were detected. Eight RT—PCR products, corresponding to six genes, were re‐amplified, sequenced and compared with the rat gene bank. Sequence analysis showed that these genes most likely encode: phosphoglucomutase‐1, neurofibromatosis‐2 interacting protein, microtubule associated protein‐2, thiamine pyrophosphokinase, and two unidentified hypothetical proteins (RNOR02022103 and ROR01044577), and that the presumed regulatory regions of these genes contained CTCT‐clusters, which are thought to be required for electromagnetic field‐dependent gene expression.
Efficacy of coeliac plexus and splanchnic nerve blockades in body and tail located pancreatic cancer pain
Authors: Özyalçın N. Süleyman , Talu Gül Köknel , Çamlıca Hakan , Erdine Serdar
Published: March 2004

Palliative treatment, pain therapy and quality of life (QOL) are very important in pancreatic cancer patients. We evaluated the pain relieving efficacy, side effects and effects on QOL of neurolytic coeliac plexus blockade (NCPB) and splanchnic nerves neurolytic blockade (SNB) in body and tail located pancreatic cancer.

The study protocol was approved by the local ethics committee. Patients were randomly divided into two groups. Coeliac group; GC, N=19 were treated with coeliac plexus blockade, whereas the patients in splanchnic group; GS, N=20 were treated with bilateral splanchnic nerve blockade. The VAS values, opioid consumption and QOL (Patient satisfaction scale=PSS, performance status scale=PS) were evaluated prior to the procedure and at 2 weeks intervals after the procedure with the survival rates.

The demographic features were found to be similar. The VAS differences (difference of every control's value with baseline value) in GS were significantly higher than the VAS differences in GC on every control meaning that VAS values in GS decreased more than the VAS values in GC. GS patients were found to decrease the opioid consumption significantly more than GC till the 6th control. GS patients had significant improvement in PS values at the first control. The mean survival rate was found to be significantly lower in GC. Two patients had severe pain during injection in GC and 5 patients had intractable diarrhoea in GC.

Comparing the ease, pain relieving efficacy, QOL‐effects of the methods, splanchnic nerve blocks may be an alternative to coeliac plexus blockade in patients with advanced body and tail located pancreatic cancer.
Sex differences in pain and analgesia: the role of gonadal hormones
Authors: Craft Rebecca M. , Mogil Jeffrey S. , Aloisi Anna Maria
Published: March 2004

There is now strong evidence for sex differences in pain and analgesia. These differences imply that gonadal steroid hormones such as estradiol and testosterone modulate sensitivity to pain and analgesia. The goal of this review is to present an overview of gonadal steroid modulation of pain and analgesia in animals and humans, and to describe mechanisms by which males' and females' biology may differentially predispose them to pain and to analgesic effects of drugs and stress. Evidence is presented to demonstrate that sex differences in pain and analgesia may be both quantitative and qualitative in nature. Current research suggests that sex‐specific management of clinical pain will be a reality in the not‐so‐distant future.
Sex‐based differences in gastrointestinal pain
Authors: Mayer Emeran A. , Berman Steve , Chang Lin , Naliboff Bruce D.
Published: March 2004

Recent interest has focused on sex‐related differences in irritable bowel syndrome (IBS) physiology and treatment responsiveness to novel pharmacologic therapies. Similar to a variety of other chronic pain conditions and certain affective disorders, IBS is more prevalent amongst women, both in population‐based studies as well as in clinic‐based surveys. Non‐painful gastrointestinal symptoms, constipation and somatic discomfort are more commonly reported by female IBS patients. While perceptual differences to rectosigmoid stimulation are only observed following repeated noxious stimulation of the gut, sex‐related differences in certain sympathetic nervous system (SNS) responses to rectosigmoid stimulation are consistently seen. Consistent with experimental findings in animals, current evidence is consistent with a pathophysiological model which emphasizes sex‐related differences in autonomic and antinociceptive responses to certain visceral stimuli.
The role of the pain‐evoked negative difference potential in dual‐task response conflict
Authors: Dowman Robert
Published: March 2004

The possible role of the generators of the sural nerve pain‐evoked negative difference potential (NDP), the anterior cingulate cortex and supplementary somatosensory area, in monitoring response conflict was investigated in 19 healthy adults. Each trial consisted of a visual arrow stimulus and a painful electrical stimulus applied to the sural nerve. The subjects determined whether their left or right sural nerve had been stimulated and whether the arrow was pointing to the left or to the right. The sural nerve pain detection task reaction times and response errors were greater in the incongruent condition, where the arrow pointed to the side opposite of that receiving the sural nerve pain, than in the congruent condition, where the arrow pointed to the same side as that receiving the sural nerve pain. Response conflict was greatest, therefore, in the incongruent condition. There were no differences in NDP amplitude across the congruent and incongruent conditions. These results argue against the hypothesis that the NDP generators are involved in monitoring response conflict.
Prevalence and characteristics of chronic pain in the general Norwegian population
Authors: Rustøen Tone , Wahl Astrid Klopstad , Hanestad Berit Rokne , Lerdal Anners , Paul Steven , Miaskowski Christine
Published: March 2004

Background. Population‐based studies suggest that prevalence of chronic pain is increasing. The purpose of this study was to determine the prevalence of chronic pain in a sample drawn from the general Norwegian population. In addition, the characteristics of chronic pain, as well as differences in demographic characteristics and health‐related variables between persons with and without chronic pain were evaluated.

Methods. A total of 4000 Norwegian citizens, were randomly drawn from the National Register, by Statistics Norway and were mailed a questionnaire.

Results. The response rate was 48.5%. The majority of the sample was female (51%), married (59%), and working for pay (69%) with a mean age of 45.2 years. The prevalence of chronic pain in the total sample was 24.4%, and 65% of the participants with chronic pain indicated that they had experienced chronic pain for over 5 years. The cause of the pain was not specified by 57% of the participants in chronic pain, and 31% reported no pain treatments. Women, older individuals, persons with less education, and those who were pensioned, reported chronic pain more frequently. The results of a logistic regression analysis indicate that the variables that provide unique contributions to predicting pain group memberships were: gender, education, being frequently ill, or having a chronic illness.

Conclusions. These findings suggest that chronic pain is a significant problem in the general Norwegian population, and that gender, education, being frequently ill, or having a chronic illness are important variables in predicting pain group membership.
Cognitive bias in systemic lupus erythematosus
Authors: Denton Fiona J. , Sharpe Louise , Schrieber Leslie
Published: March 2004

Evidence of cognitive bias in depression and anxiety has sparked an increasing interest in the potential for pain‐related bias in patients suffering from chronic pain and/or illness. Research to date has been somewhat inconsistent, and the vast majority has been conducted on just two patient populations: rheumatoid arthritis (RA) and chronic pain patients. The present study investigates cognitive bias in Systemic Lupus Erythematosus (SLE) patients, particularly in relation to disease activity and depression. Forty‐three SLE patients are compared to RA patients and healthy controls on their endorsement and recall of pain/illness words relative to depression and control words. Patients are first divided according to their disease activity, and secondly according to depression. SLE and RA patients self‐endorsed more negative illness words and fewer positive illness words than did healthy controls, regardless of disease activity or depression status. Groups did not differ in their recall patterns, although all groups demonstrated a recall bias for positive words and illness words. Post‐hoc analyses revealed a significant recall bias for disability‐related illness words compared to sensory pain words in ill, depressed patients compared to ill, non‐depressed patients and healthy controls. Consistent with the most recent research, it appears to be both the nature of the illness stimuli and the depression status of the patient that determines cognitive bias in chronically ill populations.
Single-target echo detections of jellyfish
Authors: Brierley Andrew S , Axelsen Bjørn Eric , Boyer David C , Lynam Christopher P , Didcock Carol A , Boyer Helen J , Sparks Conrad A.J , Purcell Jennifer E , Gibbons Mark J
Published: March 2004

Acoustic target-strength (TS) measurements are presented for tethered and free-swimming individual Chrysaora hysoscella (Scyphozoa) and Aequorea aequorea (Hydrozoa) medusae in Namibian waters. Tethered individual C. hysoscella (17–54 cm total umbrella diameter) and A. aequorea (19–28 cm total umbrella diameter) were ensonified at 38 kHz using a portable echosounder. Mean TS values for individual medusae at this frequency ranged from −67.3 to −52.8 dB for C. hysoscella and from −65.4 to −50.1 dB for A. aequorea. There was a positive relationship between medusa diameter and TS for both species. TS of individual medusae varied cyclically over time by about 15 dB, probably because of the periodic contraction of the medusae whilst swimming. C. hysoscella was parasitized by hyperid amphipods (maximum infestation >1800 parasites per medusa). A fluid-cylinder scattering model was used to determine the expected backscatter from the parasites, and it suggested that even at the highest observed level of infestation the jellyfish itself remained the major contributor to total backscatter at 38 kHz. Single-target echoes from targets identified by trawling as medusae were obtained from vessel-mounted echosounders at 18, 38, 120, and 200 kHz. Triangulation between echosounder beams to identify targets detected simultaneously at all four frequencies increased confidence that echoes were in fact from single targets. The 38-kHz TS values from free-swimming medusae corresponded with values obtained from tethered animals at the same frequency, providing strong evidence that the TS estimates were robust. TS values at all four frequencies (Chrysaora hysoscella mean umbrella diameter 41 cm, TS at 18 kHz = −60.0 dB, 38 kHz = −65.5 dB, 120 kHz = −68.0 dB, and 200 kHz = −70.5 dB. Aequorea aequorea mean inner-umbrella diameter 6.5 cm, TS at 18 kHz = −66.0 dB, 38 kHz = −65.5 dB, 120 kHz = −68.0 dB, and 200 kHz = −73 dB) were consistent with previously published data. Given these robust TS estimates, the possibility may now exist for multi-frequency identification and evaluation of these jellyfish species in some circumstances, and for the use of acoustic-survey techniques to estimate jellyfish abundance.
Functional characterization of podocan, a member of a new class in the small leucine‐rich repeat protein family
Authors: Shimizu-Hirota Ryoko , Sasamura Hiroyuki , Kuroda Mari , Kobayashi Emi , Saruta Takao
Published: March 2004

An important component of the extracellular matrix is the group of non‐collagenous proteins belonging to the small leucine‐rich repeat (SLR) protein family. A new SLR protein, podocan, with structural characteristics different from the known classes of the SLR protein family has been identified recently from the kidney. In this study, we examined the functional characteristics of this SLR protein expressed in cultured cells. Podocan was clearly observed intracellularly and was also detectable in the supernatant. Treatment of the expressed protein with various glycoenzymes suggested that podocan is a glycoprotein containing N‐linked oligosaccharides but not a classical proteoglycan. Moreover, podocan was found to bind type 1 collagen. Cells transfected with podocan showed reductions in cell growth and migration, concomitant with increased p21 expression. Podocan mRNA was detected by reverse transcription polymerase chain reaction not only in the kidney, but also in other tissues including the heart and vascular smooth muscle cells, suggesting that podocan may have a potential role in growth regulation in cardiovascular tissues.
Interaction of amiloride and one of its derivatives with Vpu from HIV‐1: a molecular dynamics simulation
Authors: Lemaitre V , Ali R , Kim C.G , Watts A , Fischer W.B
Published: March 2004

Vpu is an 81‐residue membrane protein, with a single transmembrane segment that is encoded by HIV‐1 and is involved in the enhancement of virion release via formation of an ion channel. Cyclohexamethylene amiloride (Hma) has been shown to inhibit ion channel activity. In the present 12‐ns simulation study a putative binding site of Hma blockers in a pentameric model bundle built of parallel aligned helices of the first 32 residues of Vpu was found near Ser‐23. Hma orientates along the channel axis with its alkyl ring pointing inside the pore, which leads to a blockage of the pore.
Towards structure determination of neurotoxin II bound to nicotinic acetylcholine receptor: a solid‐state NMR approach
Authors: Krabben Ludwig , van Rossum Barth-Jan , Castellani Federica , Bocharov Eduard , Schulga Alexey A , Arseniev Alexander S , Weise Christoph , Hucho Ferdinand , Oschkinat Hartmut
Published: March 2004

Solid‐state magic‐angle spinning nuclear magnetic resonance (NMR) has sufficient resolving power for full assignment of resonances and structure determination of immobilised biological samples as was recently shown for a small microcrystalline protein. In this work, we show that highly resolved spectra may be obtained from a system composed of a receptor–toxin complex. The NMR sample used for our studies consists of a membrane preparation of the nicotinic acetylcholine receptor from the electric organ of Torpedo californica which was incubated with uniformly 13C‐,15N‐labelled neurotoxin II. Despite the large size of the ligand–receptor complex (>290 kDa) and the high lipid content of the sample, we were able to detect and identify residues from the ligand. The comparison with solution NMR data of the free toxin indicates that its overall structure is very similar when bound to the receptor, but significant changes were observed for one isoleucine.
L‐type voltage‐gated calcium channels: understanding function through structure
Authors: Wang Ming-Chuan , Dolphin Annette , Kitmitto Ashraf
Published: March 2004

L‐type voltage‐gated calcium channels (VGCCs) are multisubunit membrane proteins that regulate calcium influx into excitable cells. Within the last two years there have been four separate reports describing the structure of the skeletal muscle VGCC determined by electron microscopy and single particle analysis methods. There are some discrepancies between the structures, as well as reports for both monomeric and dimeric forms of the channel. This article considers each of the VGCC structures in terms of similarities and differences with an emphasis upon translation of data into a biological context.
Structure of cation channels, revealed by single particle electron microscopy
Authors: Sokolova Olga
Published: March 2004

A large barrier in the way to obtaining high‐resolution structures of eukaryotic ion channels remains the expression and purification of sufficient amounts of channel protein to carry out crystallization trials. In the absence of crystals, the main available source of structural information has been electron microscopy (EM), which is well suited to the visualization of isolated macromolecular complexes and their conformational changes. The recently published EM structures outline native conformations of eukaryotic cation channels that until now have eluded crystallization. According to these results, homo‐tetrameric K+ channels have a distinct two‐layer architecture with connectors conjoining the two layers, while the pseudo‐tetrameric Ca2+ or Na+ channels are more globular and have flexible surface loops, which makes the identification of subunits complicated. Subunits can be identified using atomic structure docking into the EM maps, labeling, or deletion studies.
Cation specificity of osmosensing by the betaine carrier BetP of Corynebacterium glutamicum
Authors: Schiller Dirk , Krämer Reinhard , Morbach Susanne
Published: March 2004

The Na+/betaine carrier BetP from Corynebacterium glutamicum was purified and reconstituted in Escherichia coli phospholipid liposomes and its osmosensory properties were studied with respect to the cation specificity of osmotic activation. To dissect the influence of the co‐substrate Na+ on the energetics of uptake from its possible role as a putative trigger of osmolality‐dependent BetP activation, the internal Na+ concentration was varied without changing ΔpNa+. Studying betaine uptake at increasing luminal Na+ or K+ revealed that BetP activity was triggered by Na+ only to a negligible extent compared to activation by K+. We conclude that activation of BetP in proteoliposomes depends solely on K+, both in mechanistic and in physiological terms.
Active thrusting in the inner forearc of an erosive convergent margin, Pacific coast, Costa Rica
Authors: Fisher Donald M. , Gardner Thomas W. , Sak Peter B. , Sanchez Joanna D. , Murphy Katherine , Vannucchi Paola
Published: March 2004

Structural and geomorphic analyses of the Fila Costeña thrust belt in southwest Costa Rica indicate active thrusting within the inner forearc. The Fila Costeña exposes three major thrust faults that imbricate the late Tertiary forearc basin sequence of the Térraba basin. The frontal thrust of the Fila Costeña marks the boundary between an uplifting inner forearc and a subsiding outer forearc, with only local uplift astride the indenting Cocos Ridge. On the basis of surface constraints a cross section across the thrust belt suggests that all three thrusts flatten into parallelism with a low‐angle décollement horizon near the contact between the basement and the cover sequence of the Térraba basin. This décollement lies at a depth of ∼4 km. The minimum shortening recorded by restoration of fault‐related folds is 17 km, or 45%. Observations of late Tertiary marine sediments, tilted and faulted late Quaternary fluvial terraces, and raised Holocene marine terraces indicate that Fila Costeña uplift was likely initiated in the Quaternary and is ongoing. Given that the coastal mountains are separated from the Talamanca Range by a valley, the décollement that delaminates the forearc basin from the underthrusting forearc must continue as a flat beneath the valley but must link with the plate boundary along a crustal‐scale ramp system, a structural geometry that has resulted in uplift of the Talamanca Range, the highest peaks in Central America. The dichotomy between uplift in the inner forearc and subsidence in the outer forearc is explained in terms of the response of an arcward thickening wedge to rough, subducting crust.
More new carbon in the mineral soil of a poplar plantation under Free Air Carbon Enrichment (POPFACE): Cause of increased priming effect?
Authors: Hoosbeek Marcel R. , Lukac Martin , van Dam Douwe , Godbold Douglas L. , Velthorst Eef J. , Biondi Francesco A. , Peressotti Alessandro , Cotrufo M. Francesca , de Angelis Paolo , Scarascia‐Mugnozza Giuseppe
Published: March 2004

In order to establish suitability of forest ecosystems for long‐term storage of C, it is necessary to characterize the effects of predicted increased atmospheric CO2 levels on the pools and fluxes of C within these systems. Since most C held in terrestrial ecosystems is in the soil, we assessed the influence of Free Air Carbon Enrichment (FACE) treatment on the total soil C content (Ctotal) and incorporation of litter derived C (Cnew) into soil organic matter (SOM) in a fast growing poplar plantation. Cnew was estimated by the C3/C4 stable isotope method. Ctotal contents increased under control and FACE respectively by 12 and 3%, i.e., 484 and 107 gC/m2, while 704 and 926 gC/m2 of new carbon was sequestered under control and FACE during the experiment. We conclude that FACE suppressed the increase of Ctotal and simultaneously increased Cnew. We hypothesize that these opposite effects may be caused by a priming effect of the newly incorporated litter, where priming effect is defined as the stimulation of SOM decomposition caused by the addition of labile substrates.
Is there observational support for an El Niño‐like pattern of future global warming?
Authors: Boer G. J. , Yu B. , Kim S.‐J. , Flato G. M.
Published: March 2004

Three streams of evidence, namely simulations with coupled models, feedback analysis in the tropical Pacific, and observation‐based paleoclimate reconstructions, all support the expectation of a future mean El Niño‐like temperature response to the positive radiative forcing resulting from a continued increase in atmospheric greenhouse gas concentrations.
Pressure and temperature‐dependent quantum yields for the photodissociation of acetone between 279 and 327.5 nm
Authors: Blitz M. A. , Heard D. E. , Pilling M. J. , Arnold S. R. , Chipperfield M. P.
Published: March 2004

The photodissociation of acetone has been studied over the wavelength (λ) range 279–327.5 nm as a function of temperature (T) and pressure (p) using a spectroscopic method to monitor the acetyl (CH3CO) radical fragment. Above 310 nm the quantum yield (QY) is substantially smaller than previous measurements, and decreases with T. The QYs for production of CH3CO + CH3 and CH3 + CH3 + CO have been parameterised as a function of λ, p and T and used to calculate the altitude dependence of the photolysis frequency. In the upper troposphere (UT) the acetone photolysis lifetime is a factor of 2.5–10 longer, dependent upon latitude and season, than if the previously recommended QYs are used.
Multi‐scale compressional wave velocity structure of the San Gregorio Fault zone
Authors: Gettemy G. L. , Tobin H. J. , Hole J. A. , Sayed A. Y.
Published: March 2004

Understanding fault architecture at multiple scales is crucial to delineate in situ fault zone physical properties and rupture dynamics through modeling and geophysical imaging/monitoring. An exposure of the active large‐offset, strike‐slip San Gregorio Fault at Moss Beach, CA provides a unique field site to relate the well‐mapped fault zone architecture with compressional wave velocity (Vp) structure measured at centimeter to meter scales. Laboratory ultrasonic velocities of fault zone samples, adjusted for fluid‐related frequency and structural dispersion, indicate that (i) a seismic velocity reduction of ∼30% characterizes the central smectite‐rich clay gouge relative to the rocks 100 m away in the relatively undeformed host rocks, and (ii) the across‐fault velocity profile trends for the seismic to ultrasonic bandwidth correlate almost exactly to the previously mapped macroscale fault zone structure. These results highlight the value of conducting multiscaled investigations when measuring fault zone properties defined by physical elements at multiple scale lengths.
Convective lofting links Indian Ocean air pollution to paradoxical South Atlantic ozone maxima
Authors: Chatfield R. B. , Guan H. , Thompson A. M. , Witte J. C.
Published: March 2004

We describe a broad resolution of the “Atlantic Parado” concerning the seasonal and geographic distribution of tropical tropospheric ozone. We highlight periods of significant maximum tropospheric O3 for Jan.–April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO) maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, possible stratospheric input, and finally high‐level transport to the west, with possible mixing over Africa. For the Jan.–March highest column‐O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 20–50 days, more diffuse buildups of Indian‐to‐Atlantic pollution make important contributions.
Remote sensing of new production fuelled by nitrogen fixation
Authors: Coles Victoria J. , Wilson Cara , Hood Raleigh R.
Published: March 2004

Climatological satellite observations in the tropical North Atlantic generally show a wintertime surface chlorophyll‐a (Chl‐a) maximum except over a broad region in the western North Atlantic that has a summer Chl‐a maximum. This region also shows decoupling between Chl‐a and vertical nutrient flux, based on the positive relationship between sea surface height anomaly (SSH), sea surface temperature, and Chl‐a. An analogous summer Chl‐a maximum is simulated in a model including a dynamic representation of Trichodesmium and N2‐fixation, but not in runs without. These results suggest that the growth is fuelled by N2‐fixation. Using the observed summertime increase in Chl‐a and the model efficiency for N2‐fixation transfer to phytoplankton biomass, we calculate a nitrogen fixation rate of 220 μmol N m−2day−1 in this region. This constitutes the first satellite observation of the effect of nitrogen fixation on Chl‐a, and may ultimately provide a means of deriving new global N2‐fixation estimates.
Are there internal Kelvin waves in Lake Tanganyika?
Authors: Naithani Jaya , Deleersnijder Eric
Published: March 2004

It is generally believed that the Earth's rotation has negligible impact on the water circulation in basins which are very narrow or located near the Equator. However, herein evidence is presented of the influence of the Earth's rotation on the hydrodynamics of Lake Tanganyika, which is both very narrow (width/length ≈ 0.08) and located near the Equator. Numerical simulations exhibit small upwellings at the western shores as a result of the thermocline oscillations induced by the southeasterly winds of the dry season. These structures tend to propagate cyclonically around the lake similar to internal Kelvin waves. Numerical experiments in which f is varied concludes that internal Kelvin waves are present in Lake Tanganyika. It is also evidenced from this study that the internal Kelvin waves cannot be anticipated based on classic scaling arguments.
Structure of the magnetotail current: Kinetic simulation and comparison with satellite observations
Authors: Ricci Paolo , Lapenta Giovanni , Brackbill J. U.
Published: March 2004

The results of a three‐dimensional kinetic simulation of a Harris current sheet are used to show and reproduce the ISEE‐1/2, Geotail, and Cluster observations of the magnetotail current sheet structure. Current sheet flapping, current density bifurcation, and reconnection are explained as the results of the evolution of a Harris current sheet, where lower‐hybrid drift, kink, and tearing instabilities are involved.
Convergence vs. retreat in Southern Tyrrhenian Sea: Insights from kinematics
Authors: Pondrelli S. , Piromallo C. , Serpelloni E.
Published: March 2004

The Tyrrhenian Sea is an extensional basin opened by trench retreat and back‐arc extension during subduction of the Calabrian slab in the last 10–12 My. Subduction is still active beneath the SEmost part of the Tyrrhenian Sea, as testified by seismicity down to 500 km depth. By analyzing seismicity and geodetic data, together with recent tomographic images, we define the present‐day situation. An evident ∼N‐S compressional regime prevails in the Tyrrhenian region west of the Aeolian archipelago, while east of them a NNW‐SSE extension is documented by focal mechanisms and GPS data, with a much smaller strain rate with respect to the past. The transition between these two domains is accommodated by a N‐S discontinuity zone which runs from Aeolian Islands to Mt. Etna with an extensional to strike‐slip deformation.
Strong sensitivity of the global mean OH concentration and the tropospheric oxidizing efficiency to the source of NOx from lightning
Authors: Labrador Lorenzo J. , von Kuhlmann Rolf , Lawrence Mark G.
Published: March 2004

Production of nitrogen oxides (NOx = NO + NO2) by lightning (LtNOx) is the most uncertain among the global NOx sources, with recent estimates ranging from about 1–20 Tg(N)/yr. Previous studies of LtNOx have focused mainly on its role in the tropospheric NOy (reactive nitrogen) and O3 budgets. We show that the global mean OH concentration is also very sensitive to LtNOx. Furthermore, despite the fact that the largest changes in NOx due to lightning are in the upper troposphere, where reactions with OH are generally slower, we find that the sensitivity of the mean tropospheric lifetime of methane (CH4) and methylchloroform (CH3CCl3) to assumptions about LtNOx are as large as the sensitivity of the tropospheric O3 burden. Thus, an improved understanding of LtNOx will be important for our ability to accurately simulate the tropospheric oxidizing efficiency and its changes over time.
Reconstruction of the past total solar irradiance on short timescales
Authors: Jain Kiran , Hasan S. S.
Published: March 2004

The aim of this investigation is to present a new analysis of short‐term variations in total solar irradiance by developing regression models and to extend these to epochs when irradiance measurements were not available. In our models the sunspot area is used to quantify sunspot darkening while facular brightening is calculated using facular area, 10.7 cm radio flux and Mg II core‐to‐wing ratio. Models developed with various proxies are compared with a view to identify the role of key parameters in solar variability. We also study the relationship between different facular proxies and show that the facular area and 10.7 cm radio flux do not vary linearly with the Mg II core‐to‐wing ratio. We emphasize that the facular term in current empirical models (using facular area or radio flux proxies) on short time scale needs to have a nonlinear component in order to obtain a better correlation with observed irradiance. Our analysis demonstrates that the correlation for daily variations in solar irradiance improves by 10% using a quadratic term in the model based on radio flux as a facular proxy, which is a significant improvement on earlier models. On the other hand, the correlation remains unchanged in the model using Mg II core‐to‐wing ratio. Thus we point out that various proxies for facular brightenings contribute differently to solar irradiance. We estimate the solar irradiance variations at epochs before irradiance observation began, in particular to the start of the radio flux measurements, and find that there is no drastic increase in radiative output during the most active solar cycle 19 while for cycle 20 we observe a much lower irradiance during maximum.
Dependence of plasmaspheric morphology on the electric field description during the recovery phase of the 17 April 2002 magnetic storm
Authors: Liemohn Michael W. , Ridley Aaron J. , Gallagher Dennis L. , Ober Daniel M. , Kozyra Janet U.
Published: March 2004

A comparison of how well three different electric field models can predict the storm time plasmapause shape is conducted. The magnetic storm of 17 April 2002 is selected for this event, and plasmapause locations are extracted from images from the EUV instrument on the Imager for Magnetopause‐to‐Aurora Geomagnetic Effects (IMAGE) satellite throughout the main phase and recovery phase of the event. The three electric field descriptions are as follows: the modified McIlwain E5D analytical formula, the Weimer statistical compilation from low‐Earth orbit satellite data, and a self‐consistent Poisson equation solution for the subauroral potential pattern. It is found that all of the models have certain strengths and weaknesses in predicting the plasmapause location during this storm. The modified McIlwain model did well on the nightside but not on the dayside because the electric fields near noon are too small (analogous to too large of a conductance in the subauroral dayside ionosphere). The Weimer model did well overall, but the resulting plasmapause is usually smaller than the observed one because the electric fields are a bit too strong in the inner magnetosphere (perhaps because of an ionosphere‐magnetosphere mapping problem). The self‐consistent model is also quite good in general, but the plasmapause in the postmidnight sector was always inward of the observed one. This is because of too low a conductance at the location of the field‐aligned currents that close the partial ring current. It is concluded that the latter two models provide a sufficient description of the storm time development of the plasmaspheric morphology during this storm, with the self‐consistent model being the best choice. Another conclusion is that plasmapause locations extracted from EUV images should be compared with peak density gradients from model results rather than with any one isocontour of the cold plasma density itself.
Folding of a finite length power law layer
Authors: Schmid Daniel W. , Podladchikov Yuri Y. , Marques Fernando O.
Published: March 2004

Folding of an isolated finite length power law layer embedded in a Newtonian viscous matrix is investigated and compared to conventional folding experiments where the layer is of infinite length or in direct contact with lateral boundaries. The approach employed is a combination of the complex potential method for the basic state and the thin plate approximation for the linear stability analysis and is verified by finite element models. The resulting theory reveals that the aspect ratio of a layer has a first‐order influence on the development of folds. The aspect ratio competes with the effective viscosity contrast for dominant influence on the folding process. If the aspect ratio is substantially larger than the effective viscosity contrast, the conventional theories are applicable. In other situations, where the aspect ratio is smaller than the effective viscosity contrast, substantial corrections must be taken into account, which lead to a new folding mode that is mainly characterized by decreasing growth rates with increasing effective viscosity contrast (relative to the far‐field shortening rate). This new folding mode helps explain the absence of large wavelength to thickness ratio folds in nature, which may be due to the limitations of aspect ratios rather than large effective viscosity contrasts.