bluuebunny/crossref_metadata_2025 huggingface dataset:
Silastic® Scaphoid Implants in Osteoarthritis of the Radioscaphoid Joint
Authors: BJÖRNSSON H. A. , GESTSSON J. , EKELUND L. , HAFFAJEE D.
Published: September 2007

The long term results of Silastic® Scaphoid implants are presented in two groups of patients, with osteoarthritis of the radioscaphoid joint without known history of trauma or established pseudarthrosis of the scaphoid bone. The patients in the former group all became satisfied with the operative result whereas in the latter group only half of the patients were satisfied with the result.
An Old Cornish Hand
Authors: ROBINS ROBERT
Published: September 2007

A wooden upper limb prosthesis, made c. 1601, is illustrated with its documentation. It has remained in the possession of the descendants of its original wearer.
Foreign Body Granuloma a Cause of Trigger Thumb
Authors: FREUND E. I. , WEIGL K.
Published: September 2007

Snapping or triggering of fingers is a common complaint, the most frequent cause being tenosynovitis of the flexor tendon sheath. Injury of the flexor tendon as a precursor of triggering is infrequent. Foreign body granuloma of the tendon sheath as an antecedent factor has not been yet recorded. We report a case of stenosing tenosynovitis of the flexor tendon of the thumb caused by local reaction to a foreign body.
Instituting the science of mind: intellectual economies and disciplinary exchange at Harvard's Center for Cognitive Studies
Authors: COHEN-COLE JAMIE
Published: September 2007

Focusing on Harvard's Center for Cognitive Studies as a case, this article uses economies of research tool exchange to develop a new way of characterizing cross-disciplinary research. Throughout its life from 1960 to 1972, the Center for Cognitive Studies hosted scholars from several disciplines. However, there were two different research cultures at the Center. With its directors and patrons committed to a philosophy that equated creative science with eclectic search for and invention of new tools, the Center's initial interdisciplinary research culture emphasized the exchange of ideas and methods. Several years later, once its work was well under way, the Center's culture became multidisciplinary. Rather than emphasizing the sharing, invention, location, discussion and stabilization of new research techniques, the Center's multidisciplinary economy involved researchers working in parallel.
Standardizing wounds: Alexis Carrel and the scientific management of life in the First World War
Authors: SELCER PERRIN
Published: September 2007

This essay analyses the development of the Carrel-Dakin treatment for infected wounds during the First World War to explore the relationship between industrialized warfare and experimental medicine, the politics of standardization, and the relationship between the theories and practices of physiology and scientific management. It first describes the intellectual and institutional context from which Alexis Carrel's wound research emerged: experimental medicine and the Rockefeller Institute for Medical Research. Next the story moves to the experimental laboratory hospital on the Western Front and the quantification of wounds. Then it considers the propaganda and training campaign in support of the method at the War Demonstration Hospital located on the institute's New York City campus. The de-skilling inherent in the standardization of surgical practice was a response to the incompetence of inexperienced military surgeons, but also an attempt to restructure the medical profession into a hierarchical organization capable of being administered by elite scientist–physicians. Underlying the narrative is the paradox of simultaneous segregation of the biological and the social through laboratory practices and their conflation through the organic analogy.
Inhibition by soya isoflavones of human polymorphonuclear leukocyte function: possible relevance for the beneficial effects of soya intake
Authors: Rotondo Serenella , Krauze-Brzósko Katarzyna , Manarini Stefano , Martelli Nicola , Pecce Romina , Evangelista Virgilio , Benedetta Donati Maria , Cerletti Chiara
Published: September 2007

Lower CVD incidence is reported in Asian populations consuming soya-containing food. As polymorphonuclear leukocytes (PMN) are involved in the risk of CVD, we investigated the modulatory effect of soya isoflavones on several PMN functions and their molecular mechanismsin vitro. PMN, isolated from blood from healthy subjects, were tested upon activation with 1 μm- n-formyl-methyl-leucyl-phenylalanine (fMLP) for superoxide anion production (ferric cytochrome c reduction) and released elastase (chromogenic test). PMN homotypic aggregates stimulated by fMLP or P-selectin in dynamic conditions were detected by optical microscopy. PMN, mixed with thrombin-activated, washed platelets, formed cell aggregates, measured by flow cytometry. Phosphorylation of Pyk2, a focal adhesion kinase, was studied by immunoprecipitation and immunoblotting with specific antibodies. Genistein, daidzein and equol inhibited superoxide anion production (IC500·25 (sem0·1), 21·0 (sem4·2) and 13·0 (sem2·8) μm, respectively); the release of elastase was prevented by genistein (IC5063 (sem17) μm). PMN homotypic aggregates, stimulated by fMLP, were significantly reduced (24 (sem12) and 51 (sem14) % of control) by 100 μmgenistein and equol. P-selectin-induced aggregates were reduced to 19 (sem6), 44 (sem10) and 28 (sem9) % of control by 100 μmgenistein, daidzein and equol, respectively. Genistein, daidzein and equol also significantly reduced mixed platelet-PMN aggregates (IC504·0 (sem0·9), 57 (sem6) and 66 (sem23) μm, respectively). In PMN challenged by fMLP or P-selectin, activation of Pyk2 was prevented by isoflavones. The cardioprotective effect of soya-containing food might be linked to reduction of PMN activation and PMN-platelet interaction, novel targets for the biological effects of soya isoflavones.
Related Lending and Economic Performance: Evidence from Mexico
Authors: Maurer Noel , Haber Stephen
Published: September 2007

Related lending, a widespread practice in LDCs, is widely held to encourage bankers to loot their banks at the expense of minority shareholders and depositors. We argue that neither looting nor credit misallocation arenecessary outcomesof related lending. On the contrary, related lending often exists as a response to high information and contract-enforcement costs. Whether it encourages looting depends on other institutions, particularly those that create incentives to monitor directors. We examine Mexico's banking system, 1888–1913, in which there was widespread related lending. We find little evidence of credit misallocation, despite a financial crisis and government-organized rescue.
Memory and executive impairment in schizophrenia: comparison with frontal and temporal brain damage
Authors: Ornstein T. J. , Sahakian B. J. , McKenna P. J.
Published: September 2007

Background

Although poor neuropsychological test performance is well documented in schizophrenia, how closely it resembles that seen in patients with brain damage in terms of cognitive failures in daily life and stability over time has been little studied.

Method

Thirty patients with chronic schizophrenia, 24 patients with frontal or temporal brain damage and 30 healthy controls were given a battery of memory and executive tests. Carers of the two patient groups also completed questionnaires rating memory and executive failures in daily life. Testing was repeated 6 weeks later.

Results

The schizophrenia and the brain-damaged patients were significantly impaired on most, but not all tests. The degree of carer-rated memory or executive failure was similar in the two groups, but the schizophrenia patients were rated as having significantly more executive failures than memory failures, whereas the brain-damaged patients showed the reverse pattern. Both groups of patients showed similar consistency of performance across sessions.

Conclusions

Neuropsychological impairment in schizophrenia resembles that seen in patients with brain damage, not only in terms of overall severity, but also in terms of stability and the degree to which poor test performance translates into cognitive failures in daily life.
Topologically-directed navigation
Authors: Rawlinson David , Jarvis Ray
Published: September 2007

Recent advances in simultaneous localization and mapping permit robots to autonomously explore enclosed environments and, subsequently, navigate to selected positions within them. But, for many tasks, it is more useful to immediately navigate to goals in unexplored environments, without a map. This is possible if a human director can describe the ideal route to the robot using grounded symbols that both parties can perceive directly.

In this paper, a mobile robot is autonomously navigated to many locations in a cluttered laboratory environment by a variety of routes. A series of topological navigation instructions are provided in advance by the director, in a form that can be expressed verbally and translates easily to software representation. The instructions are based on the perception of spatial affordances available to the robot, namely nearby junctions and edges in a pruned Generalized Voronoi Diagram. The operator can generate the instructions by viewing or imagining the environment without any measurements. Only three to five instructions are needed to navigate anywhere in our laboratory. The instructions contain only topology. No spatial measurements or environmental data such as landmarks are provided to the robot.
Frühkindliche Schlaganfälle - Studie zur klinischen Validität des ET 6-6
Authors: Daseking Monika , Lemcke Julia , Macha Thorsten , Petermann Franz
Published: September 2007

Zusammenfassung: Hintergrund: Untersucht werden soll die Einsatzmöglichkeit des ET 6-6 (Entwicklungstest 6 Monate bis 6 Jahre) zur Einschätzung von Entwicklungsdefiziten bei frühkindlichem Schlaganfall. Material und Methoden: 32 Kinder mit frühkindlichem Schlaganfall wurden im Alter zwischen 36 bis 72 Monaten mit dem ET 6-6 untersucht. Die Ergebnisse werden mit den Leistungen einer altersparallelisierten Kontrollgruppe aus der Normierungsstichprobe verglichen. Anschließend erfolgt ein deskriptiver Leistungsvergleich nach Lokalisation der zerebralen Schädigung. Ergebnisse: Im Gesamtgruppenvergleich zeigt die Untersuchungsgruppe in fast allen Entwicklungsdimensionen signifikant niedrigere Leistungen als die Kontrollgruppe. Die gefundenen Leistungsdiskrepanzen werden durch den Einbezug der Lokalisation des Schlaganfalles spezifiziert; nach Schlaganfällen im Bereich der A. cerebri media linksseitig zeigen sich die deutlichsten Entwicklungsrisiken. Diskussion: Der Einsatz des ET 6-6 zeigt sich als Überblicksverfahren geeignet, um gravierende Entwicklungsdefizite oder Entwicklungsrisiken in verschiedenen Dimensionen bei frühkindlichem Schlaganfall aufzuzeigen.
Früherkennung von Sprachentwicklungsstörungen - ein Methodenvergleich
Authors: Sachse Steffi , Anke Beatrice , von Suchodoletz Waldemar
Published: September 2007

Zusammenfassung: Fragestellung: Zur Früherkennung von Sprachentwicklungsstörungen wurden in den letzten Jahren sowohl Sprachtests als auch Elternfragebögen entwickelt. In der vorliegenden Studie wurde bei zweijährigen Kindern die Vergleichbarkeit der Verfahren überprüft. Methodik: Untersucht wurden 31 Kinder mit und ohne Sprachentwicklungsverzögerungen (Alter 24 -28 Monate). Die Sprachfähigkeit wurde mit einem Elternfragebogen (ELFRA-2) und zwei Sprachtests (SETK-2, RDLS-III) erfasst. Ergebnisse: Der Sprachentwicklungsstand der Kinder wurde mit allen überprüften Verfahren recht übereinstimmend beurteilt. Zwischen Untertests, die vergleichbare Sprachdimensionen erfassen, wurden Korrelationen zwischen rSp = 0,7 und 0,9 erhoben. Die meisten Kinder, die nach dem Elternrating als sprachretardiert eingestuft wurden, waren dies auch nach den Sprachtestergebnissen. Die Sprachretardierung dieser Kinder war allerdings bei der U7 nur selten aufgefallen. Schlussfolgerungen: Mit dem Elternfragebogen ELFRA-2 lassen sich «Late Talkers» mit ähnlicher Zuverlässigkeit wie mit einem Sprachtest erfassen. Der ELFRA-2 sollte deshalb bei ambulanten Untersuchungen primär eingesetzt werden. Bei auffälligen Befunden ist eine weiterführende Sprachdiagnostik mit dem SETK-2 angezeigt. Im Gegensatz zum Elternrating liefert der SETK-2 auch Informationen über das Sprachverständnis und erlaubt eine differenziertere Einstufung des Sprachentwicklungsstandes. Die RDLS-III sollten herangezogen werden, wenn ein Kind wenig Interesse an Bildern zeigt und die Mitarbeit beim SETK-2 verweigert.
Deletion 22q11.2 und schizophrene Störungen im Kindes- und Jugendalter
Authors: Briegel Wolfgang
Published: September 2007

Zusammenfassung: Die Deletion 22q11.2 (Del.22q11.2) ist die häufigste bekannte Mikrodeletion beim Menschen und einer der wichtigsten Risikofaktoren für die Entstehung schizophrener Störungen. Fallberichte zu schizophrenen Störungen bei Kindern und Jugendlichen mit Del.22q11.2 wurden bisher jedoch kaum veröffentlicht. Nach einem Überblick über den aktuellen Wissensstand zu psychischen Störungen bei Del.22q11.2 werden Diagnostik und Behandlung eines bei Ersterkrankung 12;10-jährigen Jungen mit paranoider Schizophrenie dargestellt. Erst ca. 3 Jahre nach Erkrankungsbeginn konnte bei dem genannten Patienten nach verschiedentlichem Wechsel des Neuroleptikums das prämorbide Funktionsniveau wieder erreicht werden. Infolge Hypokalzämie kam es unter Clozapin-Gabe einmalig zu einem Krampfanfall. Der Fallbericht spricht für die Notwendigkeit regelmäßiger Kalziumspiegel-Kontrollen bei Menschen mit Del.22q11.2 und gleichzeitiger Neuroleptika-Gabe. Kinder und Jugendliche mit Del.22q11.2 sollten idealerweise bei psychischen Störungen in kinder- und jugendpsychiatrischen Spezialambulanzen behandelt werden, wegen der häufigen somatischen Probleme ist eine gute interdisziplinäre Zusammenarbeit unbedingt erforderlich.
Von Halsted zu Morrison: die Evolution in der Wiederherstellung der weiblichen Brust
Authors: Farhadi
Published: September 2007

Die Wiedererlangung eines intakten weiblichen Körperbildes nach Mastektomie gehört heute zum Gesamtkonzept in der Brustkrebsbehandlung. Eine Kontroverse, welche sich in den letzten Jahren zunehmend herauskristallisiert hat, ist die Festlegung des Zeitpunktes des Verfahrens: Primärrekonstruktion (im selben Eingriff wie Mastektomie) oder Sekundärrekonstruktion. Akzeptierte Indikationen zur Primärrekonstruktion sind DCIS und Frühkarzinome, welche keine adjuvante Therapie benötigen. Es häufen sich die Hinweise, dass die Indikation zur Primärrekonstruktion auch beim fortgeschrittenen Karzinom gestellt werden kann. Dies ist auf verbesserte Operations- und Radiotherapietechniken zurückzuführen. Der Patientenwunsch ist demnach der wichtigste Faktor in der Entscheidungsfindung zur Rekonstruktion und zur Festlegung des Zeitpunktes. Dementsprechend bedarf es spezialisierter Fachpersonen, welche die betroffene Patientin in der Entscheidungshilfe kompetent unterstützt.
Instability and surge development in debris flows
Authors: Zanuttigh Barbara , Lamberti Alberto
Published: September 2007

Debris flows are often described as a succession of surges, which are characterized by enhanced peak depth and velocity and therefore by a tremendous increase of their destructive power. For given characteristics of the base flow, if the channel is sufficiently long to allow an appreciable wave development, the linear stability analysis in shallow streams is shown to provide a reasonable prediction of the critical flow condition and of the instability growth rate. The one‐dimensional (1‐D) theory, however, does not allow the determination of the wave period of the fastest growing perturbations. Debris waves most frequently develop following a mechanism similar to water roll waves: Instabilities grow up becoming clearly distinguishable waves, and then waves overtake one another with increasing wave period and amplitude. The typical hydrograph of a multiple‐peak event is shown to be composed of a first surge, which is usually characterized by the highest depth, the longest duration, the greatest erosive power, and the most symmetrical shape, and of secondary waves that burst on the flow tail in the recession phase. The characteristics of the first surge can be explained by two different mechanisms. All waves that rise up near the flood crest run faster than this first surge and coalesce into it, causing its high depth and great volume. Moreover, segregation during the flow induces the concentration of boulders at the fronts, contributing to its depth enhancement, erosive power, and symmetrical shape. When a debris surge impacts a structure, the force pattern can be interpreted as the superposition of the reflection of the bouldery front and the formation of a vertical muddy jet due to the impact of the front wedge. Wave reflection can be described by a 1‐D mass and momentum balance across the front, whereas the pressure impulse, due to the incompressibility of the interstitial fluid, can be analyzed through inviscid formulations validated for the representation of tsunami forces.
A matter of divergence: Tracking recent warming at hemispheric scales using tree ring data
Authors: Wilson R. , D'Arrigo R. , Buckley B. , Büntgen U. , Esper J. , Frank D. , Luckman B. , Payette S. , Vose R. , Youngblut D.
Published: September 2007

No current tree ring (TR) based reconstruction of extratropical Northern Hemisphere (ENH) temperatures that extends into the 1990s captures the full range of late 20th century warming observed in the instrumental record. Over recent decades, a divergence between cooler reconstructed and warmer instrumental large‐scale temperatures is observed. We hypothesize that this problem is partly related to the fact that some of the constituent chronologies used for previous reconstructions show divergence against local temperatures in the recent period. In this study, we compiled TR data and published local/regional reconstructions that show no divergence against local temperatures. These data have not been included in other large‐scale temperature reconstructions. Utilizing this data set, we developed a new, completely independent reconstruction of ENH annual temperatures (1750–2000). This record is not meant to replace existing reconstructions but allows some degree of independent validation of these earlier studies as well as demonstrating that TR data can better model recent warming at large scales when careful selection of constituent chronologies is made at the local scale. Although the new series tracks the increase in ENH annual temperatures over the last few decades better than any existing reconstruction, it still slightly under predicts values in the post‐1988 period. We finally discuss possible reasons why it is so difficult to model post‐mid‐1980s warming, provide some possible alternative approaches with regards to the instrumental target and detail several recommendations that should be followed in future large‐scale reconstruction attempts that may result in more robust temperature estimates.
Carbon flux bias estimation employing Maximum Likelihood Ensemble Filter (MLEF)
Authors: Zupanski Dusanka , Denning A. Scott , Uliasz Marek , Zupanski Milija , Schuh Andrew E. , Rayner Peter J. , Peters Wouter , Corbin Katherine D.
Published: September 2007

We evaluate the capability of an ensemble based data assimilation approach, referred to as Maximum Likelihood Ensemble Filter (MLEF), to estimate biases in the CO2 photosynthesis and respiration fluxes. We employ an off‐line Lagrangian Particle Dispersion Model (LPDM), which is driven by the carbon fluxes, obtained from the Simple Biosphere ‐ Regional Atmospheric Modeling System (SiB‐RAMS). The SiB‐RAMS carbon fluxes are assumed to have errors in the form of multiplicative biases. Our goal is to estimate and reduce these biases and also to assign reliable posterior uncertainties to the estimated biases. Experiments of this study are performed using simulated CO2 observations, which resemble real CO2 concentrations from the Ring of Towers in northern Wisconsin. We evaluate the MLEF results with respect to the “truth” and the Kalman Filter (KF) solution. The KF solution is considered theoretically optimal for the problem of this study, which is a linear data assimilation problem involving Gaussian errors. We also evaluate the impact of forecast error covariance localization based on a new “distance” defined in the space of information measures. Experimental results are encouraging, indicating that the MLEF can successfully estimate carbon flux biases and their uncertainties. As expected, the estimated biases are closer to the “true” biases in the experiments with more ensemble members and more observations. The data assimilation algorithm has a stable performance and converges smoothly to the KF solution when the ensemble size approaches the size of the model state vector (i.e., the control variable of the data assimilation problem).
Gneiss domes, metamorphic core complexes, and wrench zones: Thermal and structural evolution of the Niğde Massif, central Anatolia
Authors: Whitney Donna L. , Teyssier Christian , Heizler Matthew T.
Published: September 2007

The Niğde Massif, a migmatite‐cored structural dome in south central Turkey, was metamorphosed, deformed, intruded, and exhumed in an oblique tectonic regime involving a switch from transpression (prograde metamorphism) to transtension (exhumation). An 80 Ma history of transpression and transtension is recorded in metamorphic rocks of the massif, and the last ∼50 Ma are recorded in both basement and overlying basin deposits. Niğde metamorphic rocks record a high‐temperature, top‐to‐north, syntranspression ductile fabric that was overprinted by lower‐grade, top‐to‐south, syntranstension ductile shear zones. The 40Ar/39Ar data for hornblende, muscovite, and biotite document rapid Late Cretaceous cooling, with the oldest Ar hornblende ages (88–79 Ma) overlapping U‐Pb ages in monazite and zircon (92–78 Ma). Muscovite Ar ages are dominantly 81–79 Ma, suggesting a short time between crystallization of high‐temperature metamorphic rocks and their cooling. Biotite Ar ages are 79–74 Ma, with the exception of disturbed samples from the eastern margin of the massif and from Eocene granitic stocks in the dome core. The eastern margin, adjacent to the sinistral Central Anatolian Fault Zone, records another cycle of burial and exhumation that overprinted earlier fabrics and disturbed isotopic systems. These two cycles of burial‐exhumation took place repeatedly along the same zone; this may be characteristic of highly oblique tectonic regimes. In the Niğde Massif, burial and exhumation became more localized and of lower amplitude over time, suggesting stabilization of the crust.
Theory for acoustic propagation in marine sediment containing gas bubbles which may pulsate in a non‐stationary nonlinear manner
Authors: Leighton T. G.
Published: September 2007

Whilst there is a considerable body of work in the literature on the theory of acoustic propagation in marine sediments, the incorporation of gas bubbles into such theories is done with the inclusion of assumptions which severely limit the applicability of those models to practical gas‐laden marine sediments. This paper provides a theory which does not assume that the bubble dynamics are linear, steady‐state and monochromatic. Such assumptions would be incompatible with many of the practical acoustic fields with which sediments are insonified today. These fields are necessarily high amplitude to provide adequate signal‐to‐noise ratios, given the high attenuation in gassy marine sediments; and often they utilise short pulses to obtain range resolution. This paper provides a theory appropriate for predicting the acoustically‐driven non‐stationary nonlinear dynamics of spherical gas bubbles embedded in a lossy elastic solid, and discusses how this could be incorporated into a nonlinear, time‐dependent propagation model.
Stochastic analysis of exit fluid temperature records from the active TAG hydrothermal mound (Mid‐Atlantic Ridge, 26°N): 2. Hidden Markov models of flow episodes
Authors: Sohn R. A.
Published: September 2007

I develop a stochastic signal model for episodic modes of variability in hydrothermal flow records using probabilistic functions of Markov processes (i.e., hidden Markov models, HMMs) and fit the model to exit fluid temperature time series data from diffuse flow sites on the active TAG hydrothermal mound. The flow states are modeled using Gamma densities to provide flexibility for application to a range of signal types. Between three and five flow states are needed to fit the diffuse flow temperature records from TAG, which correspond to models with between 10 and 28 degrees of freedom. The number of flow states required to fit a given record is related to the signal variance, with more variable records requiring a larger state space. HMMs thus provide an efficient signal model for episodic variability in hydrothermal flow records, suggesting that Markov processes may provide a means to generate stochastic subsurface flow models for deep‐sea hydrothermal fields if the spatial flow correlations can be incorporated into a statistical framework. I also use the Viterbi algorithm to “decode” the time series data into best fitting state sequences, which can be used to classify the records into discrete flow episodes. This may provide an objective means to identify discrete events in a flow record if misclassification issues arising from nonepisodic variability (e.g., tidal forcing) can be addressed.
Radiocarbon‐based circulation age of the world oceans
Authors: Matsumoto Katsumi
Published: September 2007

The distributions of deep ocean Δ14C data are often used to illustrate the rate of deep ocean circulation. The associated conventional 14C ages show a difference of 1000 years between the North Atlantic and the Southern Ocean and a difference of another 1000 years between the Southern Ocean and the North Pacific. These differences may be interpreted directly and mistakenly as the timescale of circulation. The characterization of the deep ocean circulation being millennial is common. Using objectively gridded, natural Δ14C “data” of Key et al. (2004), I recast Δ14C in terms of circulation by accounting for (1) long‐surface ocean reservoir 14C ages and (2) two sources of deep water formed in the North Atlantic and around Antarctica. The new distribution of “circulation 14C ages” is more consistent with the deep ocean being characterized by a centennial timescale than a millennial timescale. Also, the role of the southern sourced deep water is now made more obvious. By accounting for the two important controls on oceanic 14C that are not well known outside the field of chemical oceanography, the new map will be useful as an illustration of global deep ocean circulation to the wider scientific community and as a pedagogical tool to new students in Earth sciences and oceanography.
Progress in paleosalinity: Overview and presentation of a new approach
Authors: Rohling Eelco J.
Published: September 2007

This paper concerns the use of stable oxygen isotope ratios (δ18O) and stable hydrogen isotope ratios (δ2H or δD) to derive paleosalinity. First, I evaluate the potential and limitations of existing methods based on δ18O and δD separately. Next, I propose a new theoretical framework for the combined use of δ18O and δD to constrain the impact of the hydrological cycle on the surface waters and to thus characterize changes in surface water salinity. This new method is accompanied by an error propagation exercise to demonstrate its limitations and areas of potential improvement. A feasible strategy is outlined for achieving reconstructions of paleosalinity change with an uncertainty of 1 practical salinity unit or less with the newly proposed method (especially in regions with high deuterium excess values).
Ergodic transport through aquifers of non‐Gaussian log conductivity distribution and occurrence of anomalous behavior
Authors: Fiori Aldo , Janković Igor , Dagan Gedeon , Cvetković Vladimir
Published: September 2007

Three‐dimensional advective transport of passive solutes through isotropic porous formations of stationary non‐Gaussian log conductivity distributions is investigated by using an approximate semianalytical model, which is compared with accurate numerical simulations. The study is a continuation of our previous works in which formation heterogeneity is modeled using spherical nonoverlapping inclusions and an approximate analytical model was developed. Flow is solved for average uniform velocity, and transport of an ergodic plume is quantified by mass flux (traveltime distribution) at a control plane. The analytical model uses a self‐consistent argument, and it is based on the solution for an isolated inclusion submerged in homogeneous background matrix of effective conductivity. As demonstrated in the past, this analytical model accurately predicted the entire distributions of traveltimes in formations of Gaussian log conductivity distributions, as validated by numerical simulations. The present study (1) extends the results to formations of non‐Gaussian log conductivity structures (the subordination model), (2) extends the approximate analytical model to cubical blocks that tessellate the entire domain, (3) identifies a condition in conductivity distribution, at the tail of low values, that renders transport anomalous with macrodispersivity growing without bounds, and (4) provides links of our work to continuous time random walk (CTRW) methodology, as applied to subsurface transport. It is found that a class of CTRW solutions proposed in the past cannot be based on solution of flow in formations with conductivity distribution of finite integral scale.
The diverse CB1and CB2receptor pharmacology of three plant cannabinoids: Δ9‐tetrahydrocannabinol, cannabidiol and Δ9‐tetrahydrocannabivarin
Authors: Pertwee R G
Published: September 2007

Cannabis sativais the source of a unique set of compounds known collectively as plant cannabinoids or phytocannabinoids. This review focuses on the manner with which three of these compounds, (−)‐trans‐Δ9‐tetrahydrocannabinol (Δ9‐THC), (−)‐cannabidiol (CBD) and (−)‐trans‐Δ9‐tetrahydrocannabivarin (Δ9‐THCV), interact with cannabinoid CB1and CB2receptors. Δ9‐THC, the main psychotropic constituent of cannabis, is a CB1and CB2receptor partial agonist and in line with classical pharmacology, the responses it elicits appear to be strongly influenced both by the expression level and signalling efficiency of cannabinoid receptors and by ongoing endogenous cannabinoid release. CBD displays unexpectedly high potency as an antagonist of CB1/CB2receptor agonists in CB1‐ and CB2‐expressing cells or tissues, the manner with which it interacts with CB2receptors providing a possible explanation for its ability to inhibit evoked immune cell migration. Δ9‐THCV behaves as a potent CB2receptor partial agonistin vitro. In contrast, it antagonizes cannabinoid receptor agonists in CB1‐expressing tissues. This it does with relatively high potency and in a manner that is both tissue and ligand dependent. Δ9‐THCV also interacts with CB1receptors when administeredin vivo, behaving either as a CB1antagonist or, at higher doses, as a CB1receptor agonist. Brief mention is also made in this review, first of the production by Δ9‐THC of pharmacodynamic tolerance, second of current knowledge about the extent to which Δ9‐THC, CBD and Δ9‐THCV interact with pharmacological targets other than CB1or CB2receptors, and third of actual and potential therapeutic applications for each of these cannabinoids.

British Journal of Pharmacology(2008)153, 199–215; doi:10.1038/sj.bjp.0707442; published online 10 September 2007
Neuropeptide Y Y2 receptor in health and disease
Authors: Parker S L , Balasubramaniam A
Published: September 2007

We briefly survey the current knowledge and concepts regarding structure and function of the neuropeptide Y Y2 receptor and its agonists, especially as related to pharmacology of the receptor and its roles in pathological processes. Specific structural features are considered that could be responsible for the known compartmentalization and participation of the receptor in cell and tissue organization. This is further discussed in relation to changes of levels of the Y2 receptor in pathological conditions (especially in epilepsy and drug abuse), to endocytosis and recycling, and to participation in wound healing, retinopathy and angiogenesis. Properties of the receptor and of Y2 agonists are considered and reviewed in connection to the negative regulation of transmitter release, feeding, mood and social behavior. The possible involvement of the Y2 receptor in diabetes, carcinogenesis and bone formation is also reviewed.

British Journal of Pharmacology (2008) 153, 420–431; doi:10.1038/sj.bjp.0707445; published online 10 September 2007
Failure of antioxidants to protect against angiotensin II‐induced aortic rupture in aged apolipoprotein(E)‐deficient mice
Authors: Jiang F , Jones G T , Dusting G J
Published: September 2007

Background and purpose:

Oxidative stress may be involved in the development of abdominal aortic aneurysms (AAAs). Previous studies indicate that antioxidants protect against AAA formation during chronic angiotensin (Ang) II infusion in apolipoprotein E‐deficient (ApoE0) mice. We here examine if these protective effects also occurred in aged ApoE0mice.

Experimental approach:

Male ApoE0mice (50–60 weeks) were randomly divided into 4 groups: saline, Ang II (1000 ng kg−1 min−1for 4 weeks), Ang II plus antioxidants (0.1% vitamin E in food plus 0.1% vitamin C in drinking water), and Ang II plus losartan (30 mg kg−1 day−1).

Key results:

Exogenous Ang II increased systolic blood pressure by 40 mmHg and resulted in the formation of pseudoaneurysms (rupture and extramural haematoma) in the abdominal aorta in 50% of animals. True aneurysmal dilatation was rarely observed. Antioxidants decreased systemic oxidative stress (plasma malondialdehyde), but had only minor effects on aortic rupture, relative to the complete prevention by losartan. Immunohistochemistry revealed strong matrix metalloproteinase‐9 (MMP‐9) expression in atherosclerotic plaques and at the sites of rupture. Antioxidants did not affect tumour necrosis factor‐α‐stimulated MMP‐9 release from U937 cells. In addition, antioxidants had little effects on Ang II‐induced renal dysfunction.

Conclusions and implications:

In contrast to previous findings in younger mice, antioxidants had only minor effects on Ang II‐induced aortic rupture in aged mice. Our results demonstrate that the pathological features of the aneurysmal remodelling induced by Ang II in old ApoE0mice are distinct from those of human AAA.

British Journal of Pharmacology(2007)152, 880–890; doi:10.1038/sj.bjp.0707449; published online 10 September 2007
Two-dimensional granular slumps down slopes
Authors: Hogg Andrew J.
Published: September 2007

The slumping and subsequent arrest of initially motionless granular materials from behind a rapidly removed lockgate in a sloping two-dimensional channel is considered theoretically and experimentally. The theory is based upon a shallow layer description of the flow and arrest of the grains in which resistance to the downslope motion is modelled as a Coulomb drag with a constant coefficient of friction. The flows leave a thin layer of deposited material along the chute and the depth of the deposit at the rear of the lock is predicted from the theoretical model using asymptotic techniques. This analysis explains the dependence on the initial aspect ratio of the release that has been seen in previous numerical and experimental studies of granular slumps over horizontal surfaces. The theoretical predictions of this depth are also compared with laboratory observations of the slumping of four dry granular materials. It is shown that there is quantitative agreement between the experimental measurements and the theoretical predictions, which include no fitting parameters. The theoretical predictions for the length along the chute that the materials slump, however, are not in agreement with the theoretical model and potential reasons for this mismatch are discussed.
Multistage adsorption of diffusing macromolecules and viruses
Authors: Chou Tom , D’Orsogna Maria R.
Published: September 2007

We derive the equations that describe adsorption of diffusing particles onto a surface followed by additional surface kinetic steps before being transported across the interface. Multistage surface kinetics occurs during membrane protein insertion, cell signaling, and the infection of cells by virus particles. For example, viral entry into healthy cells is possible only after a series of receptor and coreceptor binding events occurs at the cellular surface. We couple the diffusion of particles in the bulk phase with the multistage surface kinetics and derive an effective, integrodifferential boundary condition that contains a memory kernel embodying the delay induced by the surface reactions. This boundary condition takes the form of a singular perturbation problem in the limit where particle-surface interactions are short ranged. Moreover, depending on the surface kinetics, the delay kernel induces a nonmonotonic, transient replenishment of the bulk particle concentration near the interface. The approach generalizes that of Ward and Tordai [J. Chem. Phys. 14, 453 (1946)] and Diamant and Andelman [Colloids Surf. A 183–185, 259 (2001)] to include surface kinetics, giving rise to qualitatively new behaviors. Our analysis also suggests a simple scheme by which stochastic surface reactions may be coupled to deterministic bulk diffusion.
Photoelectron studies on vibronic coupling in pyrazine
Authors: de Groot Mattijs , Buma Wybren Jan
Published: September 2007

Ionization pathways from the S1 and T1 states of pyrazine are investigated using one- and two-photon ionization of the excited state by both resonance enhanced multiphoton ionization photoelectron spectroscopy and zero electron kinetic energy pulsed field ionization techniques. For the triplet manifold, we show that two-photon ionization of T1 is enhanced by a vibronically induced resonance for which we determine the inducing mode and the nature of the intermediate state, as well as the 3s3(n−1) Rydberg state. For the singlet manifold, we identify the mode responsible for the vibronically induced intensity of a 3p Rydberg state that was previously found to greatly perturb the 1+2′ photoelectron spectrum of S1 by a resonance at the two-photon level.
Hall magnetohydrodynamics simulations of end-shorting induced rotation in field-reversed configurations
Authors: Macnab A. I. D. , Milroy R. D. , Kim C. C. , Sovinec C. R.
Published: September 2007

End-shorting of the open field lines that surround a field-reversed configuration (FRC) is believed to contribute to its observed rotation. In this study, nonlinear extended magnetohydrodynamics (MHD) simulations were performed that detail the end-shorting process and the resulting spin-up of the FRC. The tangential component of the electric field ET is set to zero at the axial boundaries in an extended MHD model that includes the Hall and ∇Pe terms. This shorting of the electric field leads to the generation of toroidal fields on the open field lines, which apply a torque leading to a rotation of the ions on the open field lines. The FRC then gains angular momentum through a viscous transfer from the open field line region. In addition, it is shown that spin-up is still induced when insulating boundaries are assumed.
Effects of hydrophobic and dipole-dipole interactions on the conformational transitions of a model polypeptide
Authors: Mu Yan , Gao Yi Qin
Published: September 2007

We studied the effects of hydrophobicity and dipole-dipole interactions between the nearest-neighbor amide planes on the secondary structures of a model polypeptide by calculating the free energy differences between different peptide structures. The free energy calculations were performed with low computational costs using the accelerated Monte Carlo simulation (umbrella sampling) method, with a bias-potential method used earlier in our accelerated molecular dynamics simulations. It was found that the hydrophobic interaction enhances the stability of α helices at both low and high temperatures but stabilizes β structures only at high temperatures at which α helices are not stable. The nearest-neighbor dipole-dipole interaction stabilizes β structures under all conditions, especially in the low temperature region where α helices are the stable structures. Our results indicate clearly that the dipole-dipole interaction between the nearest neighboring amide planes plays an important role in determining the peptide structures. Current research provides a more unified and quantitative picture for understanding the effects of different forms of interactions on polypeptide structures. In addition, the present model can be extended to describe DNA/RNA, polymer, copolymer, and other chain systems.
Clustering of Lennard-Jones particles in water: Temperature and pressure effects
Authors: Ferrara Gastón , McCarthy Andrés N. , Raúl Grigera J.
Published: September 2007

While the hydrophobic effect is, for many systems, one of the most relevant interactions, it may be said that in the case of biological systems this effect becomes of determinant importance. Although the matter has been analyzed extensively, certain aspects are yet to be elucidated. Hence, the study on the behavior of the hydrophobic effect with temperature, and particularly with pressure deserves further investigation; model systems may help us in the task. We have analyzed the behavior of Lennard-Jones particles in water by means of molecular dynamics simulation under different conditions of size, concentration, temperature, and pressure. Following the formation of particle aggregates we can observe an increase of the hydrophobic effect with temperature and a strong weakening of the effect at high pressures. The results agree with the experimental evidence and show the ability of molecular dynamics simulation to account for the behavior of nonpolar substances under different conditions, provided that the intermolecular interactions used are adequate.
Binomial tau-leap spatial stochastic simulation algorithm for applications in chemical kinetics
Authors: Marquez-Lago Tatiana T. , Burrage Kevin
Published: September 2007

In cell biology, cell signaling pathway problems are often tackled with deterministic temporal models, well mixed stochastic simulators, and/or hybrid methods. But, in fact, three dimensional stochastic spatial modeling of reactions happening inside the cell is needed in order to fully understand these cell signaling pathways. This is because noise effects, low molecular concentrations, and spatial heterogeneity can all affect the cellular dynamics. However, there are ways in which important effects can be accounted without going to the extent of using highly resolved spatial simulators (such as single-particle software), hence reducing the overall computation time significantly. We present a new coarse grained modified version of the next subvolume method that allows the user to consider both diffusion and reaction events in relatively long simulation time spans as compared with the original method and other commonly used fully stochastic computational methods. Benchmarking of the simulation algorithm was performed through comparison with the next subvolume method and well mixed models (MATLAB), as well as stochastic particle reaction and transport simulations (CHEMCELL, Sandia National Laboratories). Additionally, we construct a model based on a set of chemical reactions in the epidermal growth factor receptor pathway. For this particular application and a bistable chemical system example, we analyze and outline the advantages of our presented binomial τ-leap spatial stochastic simulation algorithm, in terms of efficiency and accuracy, in scenarios of both molecular homogeneity and heterogeneity.
Electroluminescence studies of (Ga,Mn)As-based p-i-n structures
Authors: Ge Z. , Lim W. L. , Chakarvorty R. , Shen S. , Liu X. , Furdyna J. K. , Dobrowolska M.
Published: September 2007

Electroluminescence (EL) and I−V characteristics were studied in a series of p-i-n heterostructures based on the ferromagnetic semiconductor (Ga,Mn)As. The configurations of the samples are p+-(Ga,Mn)As∕i-GaAs∕n+-GaAs, with or without an additional GaAs layer (doped with Be, or doped with Si) inserted into the central i layer of the p-i-n structure. For comparison, we also grew a control sample with structure GaAs:Be∕GaAs∕GaAs:Be∕GaAs∕n+-GaAs, free of intentional Mn doping. The I−V characteristics measured on all samples show good rectifying properties. The observed EL spectra indicate, however, that different recombination processes are involved in different samples. In particular, recombination involving Mn-related centers is of two types: one associated with intentional Mn doping; and the other coming from unintentionally introduced background Mn. It is important to note that the contribution to the EL signal involving the unintentionally introduced Mn is nontrivial, as can be seen in the EL spectrum observed on the control sample.
Magnetocaloric effect in reactively-milled LaFe11.57Si1.43Hy intermetallic compounds
Authors: Mandal K. , Pal D. , Gutfleisch O. , Kerschl P. , Müller K.-H.
Published: September 2007

Hydrides of LaFe11.57Si1.43 intermetallic compound have been prepared by high-energy ball milling in the presence of hydrogen gas, a process known as reactive milling. The Curie temperature of the samples was tuned within the temperature range of 199 K to 346 K by changing the hydrogen content from 0 to 2.3 at. % without compromising much of the magnitude of the magnetocaloric effect. Arrott plots and large hysteresis in the magnetization vs magnetic field curves confirm that the first-order itinerant-electron metamagnetic transition is the reason for large entropy change in the parent as well as in the hydride samples. The present study indicates that reactive milling can be an effective method for incorporating interstitial hydrogen within these compounds in order to raise their TC to room temperature.
Ballistic graphene nanoribbon metal-oxide-semiconductor field-effect transistors: A full real-space quantum transport simulation
Authors: Liang Gengchiau , Neophytou Neophytos , Lundstrom Mark S. , Nikonov Dmitri E.
Published: September 2007

A real-space quantum transport simulator for graphene nanoribbon (GNR) metal-oxide-semiconductor field-effect transistors (MOSFETs) has been developed and used to examine the ballistic performance of GNR MOSFETs. This study focuses on the impact of quantum effects on these devices and on the effect of different type of contacts. We found that two-dimensional (2D) semi-infinite graphene contacts produce metal-induced-gap states (MIGS) in the GNR channel. These states enhance quantum tunneling, particularly in short channel devices, they cause Fermi level pinning and degrade the device performance in both the ON-state and OFF-state. Devices with infinitely long contacts having the same width as the channel do not indicate MIGS. Even without MIGS quantum tunneling effects such as band-to-band tunneling still play an important role in the device characteristics and dominate the OFF-state current. This is accurately captured in our nonequilibrium Greens’ function quantum simulations. We show that both narrow (1.4 nm width) and wider (1.8 nm width) GNRs with 12.5 nm channel length have the potential to outperform ultrascaled Si devices in terms of drive current capabilities and electrostatic control. Although their subthreshold swings under forward bias are better than in Si transistors, tunneling currents are important and prevent the achievement of the theoretical limit of 60 mV/dec.