bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Results after Esophageal Resection for Cancer
Authors: Konopke  , Kersting  , Ockert  , Gastmeier  , Saeger
Published: January 2006

Zielsetzung: Das Ziel der Untersuchung war die Erfassung der Frühergebnisse nach Ösophagusresektion wegen Karzinom einschliesslich der Beurteilung des Zusammenhangs von präoperativen Risikofaktoren und postoperativer Letalität (Risikoscore nach Barthels et al. 1998). Methode: Von Oktober 1993 bis Dezember 2002 wurde bei 181 Patienten mit Ösophaguskarzinom eine Operation unter kurativem Ansatz durchgeführt. In einer prospektiven Analyse wurden Patientendaten, Charakteristika der Ösophaguskarzinome, Anteil und Art der Ösophagusresektion, Radikalität, Komplikationen und Letalität erfasst. Ergebnisse: Insgesamt konnte in 143 Fällen (79.0%) eine Resektion der Ösophaguskarzinome durchgeführt werden. Die Komplikationsrate betrug 52.5%, wobei kardio-pulmonale Komplikationen (25.9%) im Vordergrund standen. Die chirurgischen Komplikationen wurden von der Anastomoseninsuffizienz (12.6%) und der Rekurrensparese (9.1%) bestimmt. Beide Komplikationen wurden signifikant gehäuft nach Oesophagusresektion mit zervikaler Anastomosierung der Interponate beobachtet (p = 0.03 bzw. p < 0.01). Die Klinikletalität betrug 8.4%, die 30 Tage-Letalität 4.9%. Bei der Beurteilung der präoperativen Risikofaktoren wurde sowohl retro- als auch prospektiv eine niedrigere Letalität bei Patienten mit geringem Risiko (2.4% bzw. 2.3%) im Gegensatz zu denen mit mittlerem Risikoprofil (7.4% bzw. 6.4%) ermittelt. Der Patient mit hohem Risiko verstarb nach der Resektion. Diskussion und Schlussfolgerungen: Die Ergebnisse dieser Analyse zeigen, dass die Resektion von Ösophaguskarzinomen mit akzeptabler Morbidität und Mortalität möglich ist. Beachtet werden sollte, dass die Zunahme der präoperativen Risikofaktoren mit einer Erhöhung der postoperativen 30 Tage Letalität einhergeht.
Long-term Expression of Fibrogenic Cytokines in Radiation-Induced Damage to the Internal Anal Sphincter
Authors: Gervaz  , Hennig  , Buechler  , Soravia  , Brigstock  , Morel  , Egger  , Friess
Published: January 2006

Background: There is accumulating evidence, both quantitative and qualitative, that pelvic irradiation affects anorectal function. However, the molecular mechanisms responsible for radiation-induced damage to the anal sphincter remain unclear. Aim: To determine the expression of transforming growth factor-beta1 (TGF-beta1) and its downstream effector connective tissue growth factor (CTGF) in the anal sphincter of a patient irradiated for prostate cancer. Patient: A 82 year-old patient developed a rectal adenocarcinoma and underwent an abdomino-perineal resection (APR), four years after receiving pelvic irradiation for prostate carcinoma. Methods: Tissue sections of the anal sphincter were processed for histology. Immunostaining for TGF-beta1 and CTGF were performed. Results: CTGF and TGF-beta1 immunoreactivity was detected in the irradiated anal sphincter, and was absent in controls. Immunoreactivity for both cytokines predominated in the internal sphincter. CTGF and TGF-beta1 were preferentially detected in endothelial cells, myofibroblasts and fibroblasts; in addition, there was strong immunoreactivity for TGF-beta1, but not for CTGF in smooth muscle cells of the anal canal. Conclusion: Four years after pelvic irradiation, radiation-induced damage appeared to affect predominantly the smooth muscle layer of the anal canal. The molecular mechanisms responsible for radiation-induced fibrosis to these tissues involve prolonged activation of TGF-beta1 and its downstream effector CTGF.
Kidney Transplantation - New Developments
Authors: Dahm  , Weber
Published: January 2006

The standard of care for patients with end-stage renal disease is kidney transplantation, which not only confers a survival benefit compared to hemodialysis, but is also cost-effective. The indications, contraindications as well as the preoperative assessment of recipients are discussed. The recurrence rate of the underlying renal disease has to be taken into account, especially in living donation. Growing organ shortage has lead transplant surgeons to accept older, less healthy, and even non-heart-beating donors, with generally good results. Living-donation is safe for the donor, outcome is excellent and plays an increasing role today. It has surpassed the number of cadaveric kidney transplantations in some countries. Many centres now apply laparoscopic donor nephrectomy with low morbidity. Matching for ABO blood group and HLA is routinely performed, as well as pre-transplant crossmatching. The surgical procedure has been standardized and the complication rate is low. Immunosuppressive protocols have evolved over time, and while the optimal regimen has not been defined, the availability of numerous agents allows the regimen to be individualized. New agents are being introduced into clinical practice. With increasing long-term graft survival and thus life-long immunosuppression, cardiovascular disease, de-novo malignancies and infectious complications are major causes of morbidity and mortality of transplant recipients. Effective prophylactic measures are often available, and surveillance protocols are warranted in these patients. Overall, the outcome of renal transplantation is excellent and has improved over time. Future prospects include induction of allograft tolerance, tissue engineering and xenotransplantation.
Clinical Lung Transplantation - Current Status
Authors: de Perrot
Published: January 2006

Since 1983, lung transplantation has enjoyed increasing success and has become the mainstay of therapy for most end-stage lung diseases. While the first decade of clinical lung transplantation focused on technical details of the transplant procedure, the second decade was characterized by improvements in techniques of lung preservation and in the postoperative management. This review will focus on the recent improvements made in lung preservation and postoperative management.
Heart Transplantation in Lausanne from 1987 to 2003
Authors: Goy  , Seydoux  , Tinguely  , Hurni  , Ruchat  , Stumpe  , Fischer  , Gersbach  , Corno  , Mueller  , Chioléro  , Revelly  , von Segesser
Published: January 2006

Depuis l'introduction de la ciclosporine, le taux de survie après transplantation cardiaque a significativement augmenté. Nous présentons les résultats du programme de transplantation cardiaque du Centre Hospitalier Universitaire Vaudois, depuis 1987. Nous avons traité 150 patients pour insuffisance cardiaque terminale, en effectuant 152 transplantations cardiaques. Le taux de survie est comparable à celui de la littérature, soit 81%, 70% et 63% à un, cinq et 10 ans respectivement. Nous rapportons l'incidence des complications durant le suivi des patients, ainsi que les modifications de leur prise en charge au long cours.
Adult-to-Adult Living-Donor Liver Transplantation
Authors: Majno  , Mentha  , Berney  , Bühler  , Giostra  , Gelez  , Morard  , Bednarkiewicz  , Huber  , Morel
Published: January 2006

Living donor liver transplantation is a relatively new procedure in which the right side of the liver is harvested in a healthy donor and transplanted into a recipient. After the first case in 1994, over 3000 cases have been done worldwide. This review summarizes the reasons why the procedure is needed, describes its main technical aspects, highlights the boundaries in which it can be done safely, summarizes the current experience worldwide and describes the main points of the program in our unit. We argue that living-donor transplantation is a viable alternative to a long time on the waiting list for several patients, and it can be performed safely and successfully provided that all precautions are undertaken to minimize the risks in the donor and to increase the chances of a good outcome in the recipients. If these prerequisites are met, and within the framework of a structured multidisciplinary program, we believe that living-donor liver transplantation should be funded by health insurances as a recognized therapeutic option.
Medical Problems Occurring During the Long-term Follow-up after Liver Transplantation
Authors: Demirag  , Bühler  , Majno  , Berney  , Chilcott  , Giostra  , Morel  , Mentha
Published: January 2006

Liver transplantation is a standardized therapy for end-stage liver disease. With current immunosuppressive protocols and patient care, ten-year patient survival rate has reached 60%. Several medical complications may develop during this period, including renal dysfunction, hypertension, diabetes mellitus, hyperlipidemia, and metabolic bone disease. The aim of this article is to analyze long-term results of several clinical trials reporting common medical dysfunctions after liver transplantation and to discuss their management.
Five Years ATLS(R)-Courses in Switzerland
Authors: Scharplatz  , Sutter
Published: January 2006

Fünf Jahre ATLS (Advanced Trauma Life Support) in der Schweiz werden analysiert, die Schwierigkeiten bei der Einführung werden aufgezeichnet und die gezogenen Lehren im Verlauf der fünf Jahre werden geschildert. Einerseits galt es die Vorgaben von ATLS International zu berücksichtigen, anderseits die Strukturen als Untergruppe der Schweizerischen Gesellschaft für Chirurgie genau zu definieren und als interdisziplinäre Gruppierung die Querverbindungen zu den anderen Fachgruppen zu respektieren. ATLS Switzerland benötigt zudem spezielle Organisationsstrukturen mit besonderer Rücksichtnahme auf die geographisch-politischen Verhältnisse der Schweiz sowie auch auf die sprachlichen Gegebenheiten. Das Interesse an ATLS war sehr gross und lange Wartelisten erforderten eine rasche Steigerung des Kursangebotes. Dies war nur durch eine Dezentralisierung der Kurse auf fünf Kursorte möglich mit relativ selbständig arbeitenden effizienten regionalen Kurszentren. Die Kursstatistik wird analysiert, es wird eine gleichmässige Verteilung auf alle Regionen der Schweiz beobachtet, die Assistenten sind bezüglich Häufigkeit an der Spitze und unter den Teilnehmern zeigen die Chirurgen eine hauchdünne Mehrheit vor den Anästhesisten. Das Ziel ATLS in sämtlichen Notfallstationen der Schweiz einzuführen ist erreicht und auch bei der Armee werden ATLS-Kurse erteilt, insbesondere zur Vorbereitung auf Auslandeinsätze.
Osteosynthesis of Combined Injuries of the Capitellum humeri and the Radial Head
Authors: Ott  , Rikli  , Babst
Published: January 2006

Einleitung: Kombinierte Verletzungen des Capitulum humeri und des Radiusköpfchens sind selten. Meist sind neben den osteocartilaginären Schäden am Gelenk auch Verletzungen der Kollateralbänder assoziiert. Behandlungsempfehlungen für diese seltenen schwerwiegenden Ellenbogenverletzungen fehlen. Studientyp: In einer retrospektiven Analyse werden fünf Fälle untersucht, bei denen die osteocartilaginären Verletzungen des Capitulum humeri durch den gleichen Zugang, der zur Versorgung des Radiusköpfchens verwendet wurde, versorgt wurden. Die Osteosynthese erfolgte mit Mini-Titanimplantaten z.T. kombiniert mit resorbierbaren Pins. Patienten und Methode: Zwischen 1996-1999 wurden fünf Patienten (vier Männer, eine Frau) mit einer Kombinationsverletzung von Radiuskopf und Capitulum humeri operativ stabilisiert. Das Durchschnittsalter beträgt 34 Jahre (31-40 Jahre). Alle Frakturen wurden über einen direkten radialen Zugang mittels 1.5mm oder 2.0mm Zugschrauben, zum Teil mit resorbierbaren Pins stabilisiert. Anschliessend wurden die Patienten radiologisch und klinisch gemäss dem Mayo-elbow-performance Score beurteilt. Resultate: Alle Patienten konnten persönlich durch einen nicht in die Initialtherapie involvierten Untersucher nach durchschnittlich 12.8 Monaten (8-24 Monate) nachuntersucht werden. 4/5 Patienten konnten bezüglich ihrer subjektiven Einschätzung befragt werden. Radiologische Zeichen einer Nekrose des Capitulum humeri oder Arthrosezeichen fanden sich nicht. Bei drei Patienten fanden sich periartikuläre Verkalkungen. Der range of motion beträgt durchschnittlich 124 Grad (Extension 5-30 Grad, Flexion 110-145 Grad) in drei von fünf Fällen waren Sekundäreingriffe zu Mobilitätsverbesserung nötig. Der Mayo-elbow-performance Score beträgt im Mittel 85 Punkte (range 70-100 Punkte). Schlussfolgerung: Die direkte Verschraubung mit Miniimplantaten zum Teil in Kombination mit resorbierbaren Pins ermöglicht eine stabile anatomische Rekonstruktion des Capitulum humeri durch den gleichen Zugang wie er für die Stabilisierung des Radiusköpfchens notwendig ist. Die transartikuläre Fixation der kleinen Schalenfragmente des Capitulum humeri erlaubt eine sichere interfragmentäre Kompression und damit eine frühfunktionelle Rehabilitation. Sekundäreingriffe zur Verbesserung der Gelenkbeweglichkeit waren in drei von fünf Fällen nötig.
Minimally Invasive Repair of Pectus Excavatum (MIRPE) - The Basel Experience
Authors: Haecker  , Bielek  , von Schweinitz
Published: January 2006

Purpose: Minimally invasive repair of pectus excavatum (MIRPE) was first reported in 1998 by D. Nuss. This technique has gained wide acceptance during the last 4-5 years. In the meantime, some modifications of the technique have been introduced by different authors. Our retrospective study reports our own experience over the last 36 months and modifications introduced due to a number of complications. Methods: From 3/2000 to 3/2003, 22 patients underwent MIRPE. Patients median age was 15.5 years (10.7 to 20.3 years). Standardised preoperative evaluation included 3D computerised tomography (CT) scan, pulmonary function tests, cardiac evaluation with electrocardiogram and echocardiography, and photo documentation. Indications for operation included at least two of the following: Haller CT index > 3.2, restrictive lung disease, cardiac compression, progression of the deformity and severe psychological alterations. Results: In 22 patients (2 girls, 20 boys) undergoing MIRPE procedure, a single bar was used in 21 patients and two bars in one boy. Lateral stabilisers were fixed with non resorbable sutures on both sides. Overall, postoperative complications occurred in six patients (27.3%). In two patients (9.1%) a redo-procedure was necessary due to bar displacement. An additional median skin incision was performed in two patients to elevate the sternum. Pneumothorax or hematothorax in two patients resulted in routine use of a chest tube on both sides. Long-term favourable results were noted in all patients. Conclusions: The MIRPE procedure is an effective method with elegant cosmetic results. Modifications of the original method help to decrease the complication rate and to accelerate acquirement of expertise.
The Value of Ultrasonography in Patients Admitted for Acute Appendicitis
Authors: Sidler  , Heim  , Negri  , Stricker
Published: January 2006

Die Rate blander Appendices nach Appendektomie wird immer wieder kritisiert. Deshalb werden heutzutage häufig zusätzliche diagnostische Abklärungen (Sonographie/CT) vorgenommen. Welchen Stellenwert hat dabei die abdominale Ultraschalluntersuchung? Methode: Retrospektive Erfassung aller von 1.1.95 bis 31.12.98 appendektomierten Patienten im Hinblick auf Ultraschalleinsatz und Rate der histologisch verifizierten Appendizitis. Prospektive Erfassung aller von 1.1.99 bis 31.12.00 mit Verdacht auf akute Appendizitis zugewiesenen Patienten mit Festlegung der Vortest- und der Nachtestprobabilität (nach Sonographie) durch den Operateur. Resultate: Retrospektive Untersuchung: 122/132 Patienten zeigten eine akute Appendizitis (92%). Sonographieeinsatz bei 64% der Patienten. Nur eine falsch positive Sonographie. Prospektive Untersuchung: 76/99 Patienten wurden appendektomiert. 70/76 Patienten zeigten eine akute Appendizitis (92%). Sonographieeinsatz 87%. Bei histologisch blander Appendix (6) wurde bei zwei Patienten keine Probabilitätssteigerung, bei drei Patienten eine solche von nur 20% und bei einem Patienten eine Probabilitätssenkung von 20% vermerkt. Schlussfolgerung: In klinisch unklaren Situationen empfiehlt sich eine Ultraschalluntersuchung mit Festlegung einer Vor- und Nachtestprobabilität. In unseren Händen hat der Ultraschaller praktisch immer recht, die Diagnose einer akuten Appendizitis ist aber weiterhin eine Kombinationsdiagnose (Klinik und Sonographie).
Colonic Perforation after Preoperative Endoscopic Tattooing with India Ink
Authors: Gianom  , Hollinger  , Wirth
Published: January 2006

Die laparoskopische Kolonchirurgie benötigt oft als unterstützende Massnahme eine präoperative Markierung der Läsion, da dem Chirurgen die intraoperative orientierende Palpation fehlt. Die endoskopische Markierung mit Tusche ist aufgrund der Einfachheit und der langanhaltenden Markierung die Methode der Wahl. Nur wenige Komplikationen sind bei dieser Technik beschrieben. In unserem Fall traten im Anschluss an die Markierung einer idiopathischen ulzerösen Kolonveränderung progrediente Bauchschmerzen auf. Bei der Operation fand sich eine retroperitoneale gedeckte Perforation. Die entzündlichen Veränderungen waren derart, dass ein laparoskopisches Vorgehen unmöglich war und eine offene Hemikolektomie rechts notwendig war. Bei Fieber, Abdominalschmerzen und Zeichen der lokalen Peritonitis im Anschluss an eine endoskopische Tuschmarkierung muss an eine unerwünschte Reaktion auf die Tusche gedacht werden.
Peritoneal Mesothelioma after Environmental Asbestos Exposure
Authors: Rosenthal  , Langer  , Dalquen  , Marti  , Oertli
Published: January 2006

Mesothelioma are primary malignant neoplasms of the serous membranes. They usually involve the pleura and rarely the pericardium, the peritoneum and the tunica vaginalis testis. About 90% are associated with exposure to asbestos. The exposure is generally occupational, an environmental inhalation of asbestos and asbestiform fibers in areas in Turkey has been observed and presents a major health problem. This report of a patient from Anatolia with peritoneal mesothelioma after environmental exposure outlines the importance of considering this pathology in the differential diagnosis of a Turkish patient presenting with ascites.
Isolated Agenesis of the Gallbladder
Authors: Peloponissios  , Gillet  , Halkic
Published: January 2006

L'agénésie isolée de la vésicule biliaire (AVB) est une anomalie rare. Vingt-trois pour cents des porteurs de cette malformation présentent des douleurs de l'hypochondre droit accompagnées de nausées et d'intolérance aux graisses dont l'étiologie reste souvent inexpliquée. Que la méthode d'investigation initiale soit un ultrason ou une cholangiographie intraveineuse, le diagnostic retenu à tort est dans la grande majorité des cas celui d'une vésicule exclue ou scléro-atrophique. Il résulte de cette erreur une indication chirurgicale inutile avec un risque accru de lésion des voies biliaires. Le but de ce travail et de déterminer s'il est possible, malgré les pièges de l'imagerie radiologique, d'obtenir un diagnostic préopératoire et de préciser la marche à suivre en cas de découverte pré ou peropératoire d'une AVB. A partir de deux cas isolés que nous présentons dans ce travail, nous avons effectué une revue de la littérature. C'est en fait la méconnaissance de cette pathologie et sa non-évocation dans le diagnostic différentiel qui conduit à une prise en charge chirurgicale inutile et dangereuse. L'absence de structures anatomiques normales et l'impossibilité de réaliser une traction sur l'infundibulum afin de mener la dissection du triangle de Calot représente un risque accru de lésion des voies biliaires. L'évocation de ce diagnostique par le radiologue ou le chirurgien est essentielle lors de l'interprétation de l'imagerie radiologic. En cas de doute on réalisera une cholangiographie-IRM. Une transmission héréditaire de l'AVB a été observée. Les membres d'une même famille doivent être investigués.
Wind‐driven circulation for the eastern North Atlantic Subtropical Gyre from Argo data
Authors: Fraile‐Nuez Eugenio , Hernández‐Guerra Alonso
Published: January 2006

A trans‐oceanic section at 24.5°N in the North Atlantic has been sampled at a decadal frequency. This work demonstrates that the wind‐driven component of the Meridional Overturning Circulation (MOC) may be monitored using autonomous profiling floats deployed in the eastern North Atlantic Subtropical Gyre. More than 500 CTD vertical profiles from the surface to 2000 m depth, spanning one year (from April 2002 to March 2003), are used to compute the geostrophic transport stream function at 24.5°N. The baroclinic transport obtained from the autonomous profiling floats is not statistically different than that from three hydrographic cruises carried out in 1957, 1981 and 1992. A good agreement is found between the geostrophic transport stream function and the transport derived from the wind field through the Sverdrup relation.
Amplified Arctic climate change: What does surface albedo feedback have to do with it?
Authors: Winton Michael
Published: January 2006

A group of twelve IPCC fourth assessment report (AR4) climate models have Arctic (60N–90N) warmings that are, on average, 1.9 times greater than their global warmings at the time of CO2 doubling in 1%/year CO2 increase experiments. Forcings and feedbacks that impact the warming response are estimated for both Arctic and global regions based on standard model diagnostics. Fitting a zero‐dimensional energy balance model to each region, an expression is derived that gives the Arctic amplification as a function of these forcings and feedbacks. Contributing to Arctic amplification are the Arctic‐global differences in surface albedo feedback (SAF), longwave feedback and the net top‐of‐atmosphere flux forcing (the sum of the surface flux and the atmospheric heat transport convergence). The doubled CO2 forcing and non‐SAF shortwave feedback oppose Arctic amplification. SAF is shown to be a contributing, but not a dominating, factor in the simulated Arctic amplification and its intermodel variation.
A dynamical link between the Arctic and the global climate system
Authors: Dethloff K. , Rinke A. , Benkel A. , Køltzow M. , Sokolova E. , Kumar Saha S. , Handorf D. , Dorn W. , Rockel B. , von Storch H. , Haugen J. E. , Røed L. P. , Roeckner E. , Christensen J. H. , Stendel M.
Published: January 2006

By means of simulations with a global coupled AOGCM it is shown that changes in the polar energy sink region can exert a strong influence on the mid‐ and high‐latitude climate by modulating the strength of the mid‐latitude westerlies and storm tracks. It is found, that a more realistic sea‐ice and snow albedo treatment changes the ice‐albedo feedback and the radiative exchange between the atmosphere and the ocean‐sea‐ice system. The planetary wave energy fluxes in the middle troposphere of mid‐latitudes between 30 and 50°N are redistributed, which induces perturbations in the zonal and meridional planetary wave trains from the tropics over the mid‐latitudes into the Arctic. It is shown, that the improved parameterization of Arctic sea‐ice and snow albedo can trigger changes in the Arctic and North Atlantic Oscillation pattern with strong implications for the European climate.
How well do state‐of‐the‐art techniques measuring the vertical profile of tropospheric aerosol extinction compare?
Authors: Schmid B. , Ferrare R. , Flynn C. , Elleman R. , Covert D. , Strawa A. , Welton E. , Turner D. , Jonsson H. , Redemann J. , Eilers J. , Ricci K. , Hallar A. G. , Clayton M. , Michalsky J. , Smirnov A. , Holben B. , Barnard J.
Published: January 2006

The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (AIOP, May 2003) yielded one of the best measurement sets obtained to date to assess our ability to measure the vertical profile of ambient aerosol extinction σep(λ) in the lower troposphere. During one month, a heavily instrumented aircraft with well‐characterized aerosol sampling ability carrying well‐proven and new aerosol instrumentation devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from six different instruments: airborne Sun photometer (AATS‐14), airborne nephelometer/absorption photometer, airborne cavity ring‐down system, ground‐based Raman lidar, and two ground‐based elastic backscatter lidars. We find the in situ measured σep(λ) to be lower than the AATS‐14 derived values. Bias differences are 0.002–0.004 Km−1 equivalent to 13–17% in the visible, or 45% in the near‐infrared. On the other hand, we find that with respect to AATS‐14, the lidar σep(λ) are higher: Bias differences are 0.004 Km−1 (13%) and 0.007 Km−1 (24%) for the two elastic backscatter lidars (MPLNET and MPLARM, λ = 523 nm) and 0.029 Km−1 (54%) for the Raman lidar (λ = 355 nm). An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP, and we expect better agreement from the recently restored system. Looking at the collective results from six field campaigns conducted since 1996, airborne in situ measurements of σep(λ) tend to be biased slightly low (17% at visible wavelengths) when compared to airborne Sun photometer σep(λ). On the other hand, σep(λ) values derived from lidars tend to have no or positive biases. From the bias differences we conclude that the typical systematic error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state‐of‐the‐art instrumentation is 15–20% at visible wavelengths and potentially larger in the UV and near‐infrared.
Importance of spatial structures in advancing hydrological sciences
Authors: Schulz K. , Seppelt R. , Zehe E. , Vogel H. J. , Attinger S.
Published: January 2006

Spatial patterns of land surface and subsurface characteristics often exert significant control over hydrological processes at many scales. Recognition of the dominant controls at the watershed scale, which is a prerequisite to successful prediction of system responses, will require significant progress in many different research areas. The development and improvement of techniques for mapping structures and spatiotemporal patterns using geophysical and remote sensing techniques would greatly benefit watershed science but still requires a significant synthesis effort. Effective descriptions of hydrological systems will also significantly benefit from new scaling and averaging techniques, from new mathematical description for spatial pattern/structures and their dynamics, and also from an understanding and quantification of structure and pattern‐building processes in different compartments (soils, rocks, and land surface) and at different scales. The advances that are needed to tackle these complex challenges could be greatly facilitated through the development of an interdisciplinary research framework that explores instrumentation, theory, and simulation components and that is implemented in a coordinated manner.
A multiobjective discrete stochastic optimization approach to shared aquifer management: Methodology and application
Authors: Siegfried Tobias , Kinzelbach Wolfgang
Published: January 2006

Negative effects from groundwater mining are observed globally. They threaten future supply locally. Especially in semiarid to arid regions, where aquifers are the sole freshwater resource, this is problematic and can lead to an excessive rise of provision costs. Proper resource management in such environments is crucial. In many instances, however, aquifers are common property resources. In such cases and depending on resource characteristics and the nature of competing uses, their management is inherently multiobjective, and benefits from cooperative management are likely to be substantial. This paper presents a methodology for the determination of optimal, cooperative allocation policies in multiobjective aquifer management problems. Our model couples a finite difference aquifer model with an economic model that accounts for water provision costs. Discounted temporal installation and pumping and conveyance costs determine the vector‐valued objective function. Each of the objectives characterizes the individual present costs over a given time horizon that the corresponding decision makers wish to minimize. Constraint handling is implemented by the option of moving wells. A multiobjective evolutionary algorithm is coupled to the management model so as to approximate cooperative tradeoff policies on the Pareto surface. These solutions can be ranked against existing, noncooperative status quo strategies. Consequently, the simulation‐optimization model is applied to the northwest Sahara aquifer system which is used noncooperatively as a resource by Algeria, Tunisia, and Libya. We find that significant capital gains can be achieved by the establishment of intelligent pump scheduling. Since each country could benefit, a strong incentive toward the implementation of such cooperative strategies exists.
Isothermal desorption measurements of self-diffusion in supercooled o-terphenyl
Authors: Mapes Marie K. , Swallen Stephen F. , Kearns Kenneth L. , Ediger M. D.
Published: January 2006

Isothermal desorption of o-terphenyl thin-film bilayers was used to measure self-diffusion coefficients of supercooled o-terphenyl near the glass transition temperature (Tg=243K). Diffusion coefficients from 10−15.5to10−12cm2s−1 were obtained between 246 and 265K. Protio and deuterio o-terphenyl were sequentially vapor deposited, then annealed to simultaneously diffuse and desorb the sample in a vacuum chamber. During the desorption of the bilayer, the concentration of each isotope was detected by a mass spectrometer, which revealed the extent of interfacial broadening. In these experiments, isotopic interdiffusion is indistinguishable from self-diffusion and the measured interfacial broadening is consistent with Fickian diffusion. The samples prepared under several different deposition conditions yielded the same self-diffusion coefficients, indicating that the experiments were conducted in the equilibrium supercooled liquid state.
Third-order multireference perturbation theory: The n-electron valence state perturbation-theory approach
Authors: Angeli Celestino , Bories Benoît , Cavallini Alex , Cimiraglia Renzo
Published: January 2006

A formulation of the n-electron valence state perturbation theory (NEVPT) at the third order of perturbation is presented. The present implementation concerns the so-called strongly contracted variant of NEVPT, where only a subspace of the first-order interacting space is taken into account. The resulting strongly contracted NEVPT3 approach is discussed in three test cases: (a) the energy difference between the B13 and A11 states of the methylene molecule, (b) the potential-energy curve of the N2 molecule ground state, and (c) the chromium dimer (Cr2) ground-state potential-energy profile. Particular attention is devoted to the last case where large basis sets comprising also h orbitals are adopted and where remarkable differences between the second- and third-order results show up.
Confined helium atom low-lying S states analyzed through correlated Hylleraas wave functions and the Kohn-Sham model
Authors: Aquino N. , Garza Jorge , Flores-Riveros A. , Rivas-Silva J. F. , Sen K. D.
Published: January 2006

Calculation including the electron correlation effects is reported for the ground 1S1 and lowest triplet 1S3 state energies of the confined helium atom placed at the center of an impenetrable spherical box. While the adopted wave-functional treatment involves optimization of three nonlinear parameters and 10, 20, and 40 linear coefficients contained in wave functions expressed in a generalized Hylleraas basis set that explicitly incorporates the interelectronic distance r12, via a Slater-type exponent and through polynomial terms entering the expansion, the Kohn-Sham model employed here uses the Perdew and Wang exchange-correlation functional in its spin-polarized version within the local-density approximation (LDA) with and without the self-interaction correction. All these calculations predict a systematic increase in the singlet-triplet energy splitting toward the high confinement regime, i.e., when the box radius is reduced. By using the variational results as benchmark, it is found that the LDA underestimates the singlet-triplet energy splitting, whereas the self-interaction correction overestimates such a quantity.
Gradient symplectic algorithms for solving the radial Schrödinger equation
Authors: Chin Siu A. , Anisimov Petr
Published: January 2006

The radial Schrödinger equation for a spherically symmetric potential can be regarded as a one-dimensional classical harmonic oscillator with a time-dependent spring constant. For solving classical dynamics problems, symplectic integrators are well known for their excellent conservation properties. The class of gradient symplectic algorithms is particularly suited for solving harmonic-oscillator dynamics. By use of Suzuki’s rule [Proc. Jpn. Acad., Ser. B: Phys. Biol. Sci. 69, 161 (1993)] for decomposing time-ordered operators, these algorithms can be easily applied to the Schrödinger equation. We demonstrate the power of this class of gradient algorithms by solving the spectrum of highly singular radial potentials using Killingbeck’s method [J. Phys. A 18, 245 (1985)] of backward Newton-Ralphson iterations.
Adsorption and diffusion of carbon dioxide and nitrogen through single-walled carbon nanotube membranes
Authors: Skoulidas Anastasios I. , Sholl David S. , Johnson J. Karl
Published: January 2006

We have used atomically detailed simulations to examine the adsorption and transport diffusion of CO2 and N2 in single-walled carbon nanotubes at room temperature as a function of nanotube diameter. Linear and spherical models for CO2 are compared, showing that representing this species as spherical has only a slight impact in the computed diffusion coefficients. Our results support previous predictions that transport diffusivities of molecules inside carbon nanotubes are extremely rapid when compared with other porous materials. By examining carbon nanotubes as large as the (40,40) nanotube, we are able to compare the transport rates predicted by our calculations with recent experimental measurements. The predicted transport rates are in reasonable agreement with experimental observations.
Characterization of solvated electrons in hydrogen cyanide clusters: (HCN)n− (n=3, 4)
Authors: Wu Di , Li Ying , Li Zhuo , Chen Wei , Li Zhi-Ru , Sun Chia-Chung
Published: January 2006

Theoretical studies of the solvated electrons (HCN)n− (n=3, 4) reveal a variety of electron trapping possibilities in the (HCN)n (n=3, 4) clusters. Two isomers for (HCN)3− and four isomers for (HCN)4− are obtained at the MP2∕aug−cc−pVDZ+dBF (diffusive bond functions) level of theory. In view of vertical electron detachment energies (VDEs) at the CCSD(T) level, the excess electron always “prefers” locating in the center of the system, i.e., the isomer with higher coordination number shows larger VDE value. However, the most stable isomers of the solvated electron state (HCN)3− and (HCN)4− are found to be the linear C∞ν and D∞h structures, respectively, but not the fullyl symmetric structures which have the largest VDE values.
Quadratic string method for determining the minimum-energy path based on multiobjective optimization
Authors: Burger Steven K. , Yang Weitao
Published: January 2006

Based on a multiobjective optimization framework, we develop a new quadratic string method for finding the minimum-energy path. In the method, each point on the minimum-energy path is minimized by integration in the descent direction perpendicular to path. Each local integration is done on a quadratic surface approximated by a damped Broyden-Fletcher-Goldfarb-Shanno updated Hessian, allowing the algorithm to take many steps between energy and gradient calls. The integration is performed with an adaptive step-size solver, which is restricted in length to the trust radius of the approximate Hessian. The full algorithm is shown to be capable of practical superlinear convergence, in contrast to the linear convergence of other methods. The method also eliminates the need for predetermining such parameters as step size and spring constants, and is applicable to reactions with multiple barriers. The effectiveness of this method is demonstrated for the Müller-Brown potential, a seven-atom Lennard-Jones cluster, and the enolation of acetaldehyde to vinyl alcohol.
Electrical and dielectric behaviors of Ti3SiC2∕hydroxyapatite composites
Authors: Shi Sui-Lin , Pan Wei , Han Ruo-Bing , Wan Chun-Lei
Published: January 2006

Ti 3 SiC 2 ∕ Hydroxyapatite composites were prepared by spark plasma sintering. The effective dc conductivity and dielectric behavior of the composites were studied. The percolation theory was applied to demonstrate the dielectric behavior of the composites. The experimental results showed that the dielectric constant increased greatly with the Ti3SiC2 concentration, and can reach as high as 700 when the Ti3SiC2 concentration was close to the percolation threshold.
Near-field spectroscopy of low-loss waveguide integrated microcavities
Authors: Cluzel B. , Picard E. , Charvolin T. , Hadji E. , Lalouät L. , de Fornel F. , Sauvan C. , Lalanne P.
Published: January 2006

A scanning near-field spectroscopy method is used to observe loss reduction and Q-factor enhancement due to transverse-mode profile matching within photonic-crystal microcavities. Near-field measurements performed directly on cavity modes are compared with three-dimensional calculations and quantitative agreement is observed.
Selection of biocatalysts for chemical synthesis
Authors: van Sint Fiet Stephan , van Beilen Jan B. , Witholt Bernard
Published: January 2006

To determine whether microbial chemosensors can be used to find new or better biocatalysts, we constructed
Escherichia coli
hosts that recognize the product of a biocatalytic conversion through the transcriptional activator NahR and respond by expression of a
lacZ
or
tetA
reporter gene. Equipped with a benzaldehyde dehydrogenase (XylC from
Pseudomonas putida
), the
lacZ
-based host responded to the oxidation of benzaldehyde and 2-hydroxybenzaldehyde to the corresponding benzoic acids by forming blue colonies, whereas XylC
−
cells did not. Similarly, the
tetA
-based host was able to grow under selective conditions only when equipped with XylC, enabling selection of biocatalytically active cells in inactive populations at frequencies as low as 10
−6
.
Abscisic acid-dependent multisite phosphorylation regulates the activity of a transcription activator AREB1
Authors: Furihata Takashi , Maruyama Kyonoshin , Fujita Yasunari , Umezawa Taishi , Yoshida Riichiro , Shinozaki Kazuo , Yamaguchi-Shinozaki Kazuko
Published: January 2006

bZIP-type transcription factors AREBs/ABFs bind an abscisic acid (ABA)-responsive cis-acting element named ABRE and transactivate downstream gene expression in
Arabidopsis
. Because
AREB1
overexpression could not induce downstream gene expression, activation of AREB1 requires ABA-dependent posttranscriptional modification. We confirmed that ABA activated 42-kDa kinase activity, which, in turn, phosphorylated Ser/Thr residues of R-X-X-S/T sites in the conserved regions of AREB1. Amino acid substitutions of R-X-X-S/T sites to Ala suppressed transactivation activity, and multiple substitution of these sites resulted in almost complete suppression of transactivation activity in transient assays. In contrast, substitution of the Ser/Thr residues to Asp resulted in high transactivation activity without exogenous ABA application. A phosphorylated, transcriptionally active form was achieved by substitution of Ser/Thr in all conserved R-X-X-S/T sites to Asp. Transgenic plants overexpressing the phosphorylated active form of AREB1 expressed many ABA-inducible genes, such as
RD29B
, without ABA treatment. These results indicate that the ABA-dependent multisite phosphorylation of AREB1 regulates its own activation in plants.
In vivo
imaging of juxtaglomerular neuron turnover in the mouse olfactory bulb
Authors: Mizrahi Adi , Lu Jing , Irving Ryan , Feng Guoping , Katz Lawrence C.
Published: January 2006

As a consequence of adult neurogenesis, the olfactory bulb (OB) receives a continuous influx of newborn neurons well into adulthood. However, their rates of generation and turnover, the factors controlling their survival, and how newborn neurons intercalate into adult circuits are largely unknown. To visualize the dynamics of adult neurogenesis, we produced a line of transgenic mice expressing GFP in ≈70% of juxtaglomerular neurons (JGNs), a population that undergoes adult neurogenesis. Using
in vivo
two-photon microscopy, time-lapse analysis of identified JGN cell bodies revealed a neuronal turnover rate of ≈3% of this population per month. Although new neurons appeared and older ones disappeared, the overall number of JGNs remained constant. This approach provides a dynamic view of the actual appearance and disappearance of newborn neurons in the vertebrate central nervous system, and provides an experimental substrate for functional analysis of adult neurogenesis.
A fast response mechanism for insulin storage in crystals may involve kink generation by association of 2D clusters
Authors: Georgiou Dimitra K. , Vekilov Peter G.
Published: January 2006

Crystals that are likely rhombohedral of Zn–insulin hexamers form in the islets of Langerhans in the pancreases of many mammals. The suggested functions of crystal formation is to protect the insulin from proteases and increase the degree of conversion of soluble proinsulin. To accomplish these ends, crystal growth should be fast and adaptable to rate fluctuations in the conversion reaction. Zn–insulin crystals grow layer by layer. Each layer spreads by the attachment of molecules to kinks located at the layers’ edges, also called steps. The kinks are thought to be generated either by thermal fluctuations, as postulated by Gibbs, or by 1D nucleation of new crystalline rows. The kink density determines the rate at which steps advance, and these two kink-generation mechanisms lead to weak near-linear responses of the growth rate to concentration variations. We demonstrate for the crystallization of Zn–insulin a mechanism of kink generation whereby 2D clusters of several insulin molecules preformed on the terraces between steps associate to the steps. This mechanism results in several-fold-higher kink density, a faster rate of crystallization, and a high sensitivity of the kinetics to small increases of the solute concentration. If the found mechanism operates during insulin crystallization
in vivo
, it could be a part of the biological regulation of insulin production and function. For other crystallizing materials in biological and nonbiological systems, this mechanism provides an understanding of the often seen nonlinear acceleration of the kinetics.
Imaging hair cell transduction at the speed of sound: Dynamic behavior of mammalian stereocilia
Authors: Fridberger Anders , Tomo Igor , Ulfendahl Mats , Boutet de Monvel Jacques
Published: January 2006

The cochlea contains two types of sensory cells, the inner and outer hair cells. Sound-evoked deflection of outer hair cell stereocilia leads to fast force production that will enhance auditory sensitivity up to 1, 000-fold. In contrast, inner hair cells are thought to have a purely receptive function. Deflection of their stereocilia produces receptor potentials, transmitter release, and action potentials in the auditory nerve. Here, we describe a method for rapid confocal imaging. The method was used to image stereocilia during simultaneous sound stimulation in an
in vitro
preparation of the guinea pig cochlea. We show that inner hair cell stereocilia move because they interact with the fluid surrounding the hair bundles, but stereocilia deflection occurs at a different phase of the stimulus than is generally expected. In outer hair cells, stereocilia deflections were ≈1/3 of the reticular lamina displacement. Smaller deflections were found in inner hair cells. The ratio between stereocilia deflection and reticular lamina displacement is important for auditory function, because it determines the stimulus applied to transduction channels. The low ratio measured here suggests that amplification of hair-bundle movements may be necessary
in vivo
to preserve transduction fidelity at low stimulus levels. In the case of the inner hair cells, this finding would represent a departure from traditional views on their function.
The metabolic syndrome resulting from a knockout of the NEIL1 DNA glycosylase
Authors: Vartanian Vladimir , Lowell Brian , Minko Irina G. , Wood Thomas G. , Ceci Jeffrey D. , George Shakeeta , Ballinger Scott W. , Corless Christopher L. , McCullough Amanda K. , Lloyd R. Stephen
Published: January 2006

Endogenously formed reactive oxygen species continuously damage cellular constituents including DNA. These challenges, coupled with exogenous exposure to agents that generate reactive oxygen species, are both associated with normal aging processes and linked to cardiovascular disease, cancer, cataract formation, and fatty liver disease. Although not all of these diseases have been definitively shown to originate from mutations in nuclear DNA or mitochondrial DNA, repair of oxidized, saturated, and ring-fragmented bases via the base excision repair pathway is known to be critical for maintaining genomic stability. One enzyme that initiates base excision repair of ring-fragmented purines and some saturated pyrimidines is NEIL1, a mammalian homolog to
Escherichia coli
endonuclease VIII. To investigate the organismal consequences of a deficiency in NEIL1, a knockout mouse model was created. In the absence of exogenous oxidative stress,
neil1
knockout (
neil1
−/−
) and heterozygotic (
neil1
+/−
) mice develop severe obesity, dyslipidemia, and fatty liver disease and also have a tendency to develop hyperinsulinemia. In humans, this combination of clinical manifestations, including hypertension, is known as the metabolic syndrome and is estimated to affect >40 million people in the United States. Additionally, mitochondrial DNA from
neil1
−/−
mice show increased levels of steady-state DNA damage and deletions relative to wild-type controls. These data suggest an important role for NEIL1 in the prevention of the diseases associated with the metabolic syndrome.
Interaction of MEQ protein and C-terminal-binding protein is critical for induction of lymphomas by Marek’s disease virus
Authors: Brown Andrew C. , Baigent Susan J. , Smith Lorraine P. , Chattoo Jason P. , Petherbridge Lawrence J. , Hawes Pippa , Allday Martin J. , Nair Venugopal
Published: January 2006

Marek’s disease virus (MDV) is an oncogenic herpesvirus that induces fatal T cell lymphomas in chickens. With more than 20 billion doses of vaccine used annually, vaccination constitutes the cornerstone of Marek’s disease control. Despite the success of vaccination, evolution of virulence among MDV strains continues to threaten the effectiveness of the current Marek’s disease vaccines. MDV-encoded protein MEQ (MDV EcoRI Q) probably acts as a transcription factor and is considered to be the major MDV oncoprotein. MEQ sequence shows a Pro-Leu-Asp-Leu-Ser (PLDLS) motif known to bind C-terminal-binding protein (CtBP), a highly conserved cellular transcriptional corepressor with roles in the regulation of development, proliferation, and apoptosis. Here we show that MEQ can physically and functionally interact with CtBP through this motif and that this interaction is critical for oncogenesis because mutations in the CtBP-interaction domain completely abolished oncogenicity. This direct role for MEQ–CtBP interaction in MDV oncogenicity highlights the convergent evolution of molecular mechanisms of neoplastic transformation by herpesviruses because Epstein–Barr virus oncoproteins EBNA 3A and 3C also interact with CtBP. We also demonstrate that the nononcogenic MDV generated by mutagenesis of the CtBP-interaction domain of MEQ has the potential to be an improved vaccine against virulent MDV infection. Engineering MDV with precisely defined attenuating mutations, therefore, represents an effective strategy for generating new vaccines against this major poultry disease.