Large International Effort Research Articles

Characterization of a CZT focal plane small prototype for hard X-ray telescope

The promise of good energy and spatial resolution coupled with high efficiency and room temperature operation has fuelled a large international effort to develop cadmium zinc telluride (CZT) for hard X-ray applications. We are involved on the development of a hard X-ray telescope based on multilayer optics and focal plane detector operative in the 10-80 keV energy range. This telescope requires a high efficiency focal plane providing both fine spatial resolution and spectroscopy with a compact and robust design. This paper reports preliminary results on the characterization both in spectroscopic and spatial response of two small pixellated CZT detectors (10times10times1 mm3 and 10times10times2 mm3 single crystals) with 0.45 mm pixel size. We present the results obtained using both standard commercial read-out electronics Readout Electronics for Nuclear Applications (RENA) and innovative low noise and low power dissipation ASICs developed within the collaboration

Repeat hydrography cruises reveal chemical changes in the North Atlantic

The U.S. contribution to a large international effort to document long‐term trends in carbon storage and transport in the global oceans by reoccupying selected hydrographic sections on decadal timescales began with three North Atlantic cruises in 2003. The initial results from these reoccupation cruises have shown significant long‐term changes in oxygen, carbon dioxide (CO2), and several other measurable parameters since the last global survey, which occurred in 1993.The ocean has a memory of the climate system and is second only to the Sun in affecting variability in the seasons and longterm climate change. The ocean stores an estimated 1000 times more heat than the atmosphere, and 50 times more carbon. Additionally the key to possible abrupt climate change may lie in deep‐ocean circulation.

Pierre Auger Observatory: status report

The Pierre Auger Observatory is a large international effort to provide measurements of extensive air showers (EAS) initiated in the upper atmosphere by cosmic rays with energies above 10(18) eV , the Ultra High Energy Cosmic Rays (UHECR's). The explanations for the origin, acceleration processes and composition of the UHECR's face theoretical and experimental difficulties, due to the extremely low flux in this energy region. The full observatory will consist of a hybrid detector using an array of 1600 water <IMG SRC="/img/revistas/bjp/v34n4a/a16img01.gif">erenkov tanks spread over an area of 3000 km² overlooked by a set of 4 air fluorescence detectors per site. The southern site is being instrumented in Argentina and I will discuss its present status in this paper.

Recent approaches to modeling ionospheric weather

The ionosphere is a complex and dynamic medium that exhibits weather features at all latitudes and longitudes. The weather features are driven by internal processes as well as by interplanetary and magnetospheric phenomena. Because ionospheric weather can have a detrimental effect on both ground-based and space-based systems, a large international effort has been devoted to developing both specification and forecast models, with the aim of predicting the occurrence, duration, and intensity of weather features. Currently, the most promising ionospheric weather models are the physics-based data-driven models that use Kalman filter data assimilation techniques. The data assimilation is used both to obtain the inputs needed by the physics-based models and to adjust the model outputs, i.e., the calculated electron density distribution. The data sources used in the physics-based assimilation models include ground-based GPS/TEC data, bottomside electron density profiles obtained from digisondes, in situ DMSP satellite measurements, satellite-to-satellite occultation data, TECs obtained from satellites with radio beacons, and UV data obtained via remote sensing. The status of the modeling will be reviewed.

A handbook of protocols for standardised and easy measurement of plant functional traits worldwide

There is growing recognition that classifying terrestrial plant species on the basis of their function (into 'functional types') rather than their higher taxonomic identity, is a promising way forward for tackling important ecological questions at the scale of ecosystems, landscapes or biomes. These questions include those on vegetation responses to and vegetation effects on, environmental changes (e.g. changes in climate, atmospheric chemistry, land use or other disturbances). There is also growing consensus about a shortlist of plant traits that should underlie such functional plant classifications, because they have strong predictive power of important ecosystem responses to environmental change and/or they themselves have strong impacts on ecosystem processes. The most favoured traits are those that are also relatively easy and inexpensive to measure for large numbers of plant species. Large international research efforts, promoted by the IGBP–GCTE Programme, are underway to screen predominant plant species in various ecosystems and biomes worldwide for such traits. This paper provides an international methodological protocol aimed at standardising this research effort, based on consensus among a broad group of scientists in this field. It features a practical handbook with step-by-step recipes, with relatively brief information about the ecological context, for 28 functional traits recognised as critical for tackling large-scale ecological questions.

8:30 Implementation of clinical practice guidelines in workers compensation board patients with acute mechanical back pain: a prospective randomized trial

Purpose of study: The study objectives were to assess the degree to which the patterns of practice of primary care physicians in managing workers compensation board (WCB) patients are in compliance with current practice guidelines and determine whether providing family physicians and their patients with the guidelines would alter the degree of adherence.Methods used: A total of 724 patients with nonradicular lower back pain of less than 2 weeks duration and accepted WCB claims were randomized into five groups: Group 1, physicians received a single information package summarizing the guidelines for managing acute mechanical back pain at 0 to 4 weeks after injury; Group 2, physicians received the same package and, in addition, their patients received a layperson's summary of the guidelines at 0 to 4 weeks after injury; Group 3, physicians received the information package three times, at 0–4-week, 5–8-week and 8–12-week postinjury periods; Group 4, physicians and their patients received the information packages at the 0–4 week, 5–8 week and 8–12-week postinjury periods; Group 5, neither the physicians nor their patients received any guideline information (control group). The compulsory WCB physician report forms were collected and scored. The primary outcome was compliance with guideline recommendations regarding specific patient history items, physical examination procedures and treatment recommendations. The chi-squared test was used to compare the five groups.of findings: Primary care physicians in the control group demonstrated a high degree of compliance with the recommended history taking, physical examination procedures and imaging guidelines but were in poor compliance with the guideline-recommended treatments. Providing the physicians ± patients with a single information package (ie, Groups 1 and 2) did not result in any significant improvement in compliance. Information provided at three separate intervals (Group 3) improved compliance with some recommended treatments, such as exercise, medications, less use of bed rest and passive physiotherapy, but not others including recommendation for spinal manipulation, work modification and return to normal activity. No added benefit was observed when providing patients with an information package (Group 4).Relationship between findings and existing knowledge: In the last 8 years, 12 countries have published evidence-based guidelines to assist primary care physicians in the management of acute and chronic lower back pain. Despite this large international effort and high degree of agreement among independent multidisciplinary panels of experts, a number of studies have demonstrated that the implementation of the guidelines has been largely unsuccessful. No prior published studies have examined guideline implementation strategies in primary care physicians managing WCB patients. The results of this study provide convincing evidence that ignorance of the guidelines is not the only contributing factor in determining the patterns of practice of primary care physicians.Overall significance of findings: Providing physicians with information regarding clinical practice guidelines for the management of acute back pain at three stages of the patient's clinical course (ie, 0 to 4, 4 to 8 and 8 to 12 weeks after injury) altered some aspects of physician pattern of practice, but results were not ideal. Alternate strategies need to be developed for improving physician compliance with clinical practice guidelines for treatment of WCB patients with acute lower back pain.Disclosures: No disclosures.Conflict of interest: Dr. Paul Bishop, grant research support from the Workers Compensation Board of British Columbia.

Preliminary performance of CdZnTe imaging detector prototypes

The promise of good energy and spatial resolution coupled with high efficiency and near-room-temperature operation has fuelled a large international effort to develop cadmium–zinc–telluride (CdZnTe) for the hard-X-ray region. We present, here, preliminary results from our development of small-pixel imaging arrays fabricated on 5×5×1-mm and 5×5×2-mm spectroscopy and discriminator-grade material. Each array has 16 (4×4) 0.65-mm gold readout pads on a 0.75-mm pitch, with each pad connected to a discrete preamplifier via a pulse-welded gold wire. Each array is mounted on a three-stage Peltier cooler and housed in an ion-pump-evacuated housing which also contains a hybrid microassembly for the 16 channels of electronics. We have investigated the energy resolution and approximate photopeak efficiency for each pixel at several energies and have used an ultra-fine beam X-ray generator to probe the performance at the pixel boundaries. Both arrays gave similar results and at an optimum temperature of −20°C we achieved between 2% and 3% full-width at half-maximum energy resolution at 60 keV and around 15% at 5.9 keV. We found that all the charge was contained within one pixel except very close to the pixels edge, where it would start to be shared with its neighbor. Even between pixels, all the charge would be appropriately shared with no apparently loss of efficiency or resolution. Full details of these measurements will be presented, together with their implications for future imaging-spectroscopy applications.

Valsartan in Acute Myocardial Infarction Trial (VALIANT): Rationale and design

Background Survivors of acute myocardial infarction (MI) complicated by heart failure and/or resulting in left ventricular dysfunction are at heightened risk for subsequent death and major nonfatal cardiovascular events. Inhibition of the renin-angiotensin system with an angiotensin-converting enzyme inhibitor has consistently been demonstrated to result in reductions in these risks by approximately 20%. The development of angiotensin II receptor blockers offers a new, more specific, and theoretically more complete pharmacologic mode to inhibit the adverse influence of angiotensin II. Methods Valsartan in Acute Myocardial Infarction (VALIANT) is a multicenter, double-blind, randomized, active controlled parallel group study comparing the efficacy and safety of long-term treatment with valsartan, captopril, and their combination in high-risk patients after MI. The trial is designed with 3 arms, giving equal statistical consideration to survival comparisons of captopril versus the angiotensin II receptor blocker valsartan, as well as the combination of captopril plus valsartan, compared with a proven effective dose of captopril. This 14,500-patient trial is designed with an 86% power to detect a 15% reduction in mortality rate with either use of valsartan compared with captopril. The trial encourages optimal individualization of other proven therapies in acute and chronic infarction, and the international patient body ensures good representation of multiple practice patterns. Conclusion VALIANT is a large international investigative effort that will evaluate the role of valsartan in the management of patients with MI associated with heart failure and/or left ventricular dysfunction. The use of a proven dose of captopril and the comparator arms with valsartan alone or in combination with captopril provides a unique test of whether the angiotensin II receptor blocker can make an additional improvement in clinical outcomes beyond angiotensin-converting enzyme inhibitors. (Am Heart J 2000;140:727-34.)

Tumor suppression and apoptosis of human prostate carcinoma mediated by a genetic locus within human chromosome 10pter-q11.

Prostate cancer is the second leading cause of male cancer deaths in the United States. Yet, despite a large international effort, little is known about the molecular mechanisms that underlie this devastating disease. Prostate secretory epithelial cells and androgen-dependent prostate carcinomas undergo apoptosis in response to androgen deprivation and, furthermore, most prostate carcinomas become androgen independent and refractory to further therapeutic manipulations during disease progression. Definition of the genetic events that trigger apoptosis in the prostate could provide important insights into critical pathways in normal development as well as elucidate the perturbations of those key pathways in neoplastic transformation. We report the functional definition of a novel genetic locus within human chromosome 10pter-q11 that mediates both in vivo tumor suppression and in vitro apoptosis of prostatic adenocarcinoma cells. A defined fragment of human chromosome 10 was transferred via microcell fusion into a prostate adenocarcinoma cell line. Microcell hybrids containing only the region 10pter-q11 were suppressed for tumorigenicity following injection of microcell hybrids into nude mice. Furthermore, the complemented hybrids undergo programmed cell death in vitro via a mechanism that does not require nuclear localization of p53. These data functionally define a novel genetic locus, designated PAC1, for prostate adenocarcinoma 1, involved in tumor suppression of human prostate carcinoma and furthermore strongly suggest that the cell death pathway can be functionally restored in prostatic adenocarcinoma.

Global atmospheric watch adds six new stations

With the growing awareness that global atmospheric change may well have far reaching implications for life on Earth, the study of atmospheric chemistry is rapidly intensifying. Essential to understanding the changing atmosphere are global measurements of several key components, for example carbon dioxide, methane, and ozone. As part of a large international effort, the World Meteorological Organization is organizing the Global Atmospheric Watch, a network of more than 300 regional monitoring stations scattered across the globe. There are also several stations that can sample air that is representative of large, unpolluted areas (see Figure 1), and this part of the network is being extended. Six new stations are being added in Algeria, Argentina, Brazil, China, Indonesia, and Kenya, nations that until now have been minimally involved in studying atmospheric chemistry.

The Human Genome Project and the breast-ovarian cancer gene

The Human Genome Project is a large scale international effort to create physical, genetic, and nucleotide sequence maps of the entire human genome. This initiative, which was begun in 1990, is expected to achieve its goal of sequencing the entire human genome by the year 2005. Undoubtedly, this massive resource will substantially enhance our ability to diagnose predisposition to disease at the genetic level and will provide us with important biologic information that can be used in the treatment and prevention of disease.

Model validation: a systemic and systematic approach

Abstract The term ‘validation’ is used ubiquitously in association with the modelling activities of numerous disciplines including social, political, natural, physical sciences, and engineering. There is however, a wide range of definitions which give rise to very different interpretations of what activities the process involves. Analyses of results from the present large international effort in modelling radioactive waste disposal systems illustrate the urgent need to develop a common approach to model validation. Some possible explanations are offered to account for the present state of affairs. We believe that a rigorous approach to validation must necessarily be based on a thorough understanding and application of the theory of simulation and modelling. The methodology developed treats model validation and code verification in a systemic and systematic fashion. In fact, this approach may be regarded as a comprehensive framework to assess the adequacy of any simulation study.

The Human Genome Project

The recently initiated human genome project is a large international effort to elucidate the genetic architecture of the genomes of man and several model organisms. The initial phases of this endeavor involve the establishment of rough blueprints (maps) of the genetic landscape of these genomes, with the long-term goal of determining their precise nucleotide sequences and identifying the genes. The knowledge gained by these studies will provide a vital tool for the study of many biologic processes and will have a profound impact on clinical medicine.

The human genome project. Prospects and implications for clinical medicine

The recently initiated human genome project is a large international effort to elucidate the genetic architecture of the genomes of man and several model organisms. The initial phases of this endeavor involve the establishment of rough blueprints (maps) of the genetic landscape of these genomes, with the long-term goal of determining their precise nucleotide sequences and identifying the genes. The knowledge gained by these studies will provide a vital tool for the study of many biologic processes and will have a profound impact on clinical medicine.

The Human Genome Project

The recently initiated human genome project is a large international effort to elucidate the genetic architecture of the genomes of man and several model organisms. The initial phases of this endeavor involve the establishment of rough blueprints (maps) of the genetic landscape of these genomes, with the long-term goal of determining their precise nucleotide sequences and identifying the genes. The knowledge gained by these studies will provide a vital tool for the study of many biologic processes and will have a profound impact on clinical medicine.

Preventable Blindness in Disasters: Visual Status Among Indochinese Refugees

A survey conducted among Indochinese refugees in Thailand in 1979, revealed significant levels of Vitamin A deficiency blindness (xerophthalmia). A Vitamin A supplementation program for children was implemented. Recent events in South East Asia have resulted in the mass movements of thousands of Kampucheans. These people underwent extreme deprivation for several years before migrating in large numbers to the Thai-Kampuchean border and later into Thailand. This massive influx of starving and ill men, women and children stimulated a large international relief effort aimed at providing food, shelter and health care. Under the supervision of the United Nations High Commission for Refugees, several holding centers or camps were established within Thailand.Early reports indicated severe problems with malnutrition among the children reaching these areas. Since these malnourished children were susceptible to a blinding affliction, xerophthalmia, Helen Keller International, a voluntary agency long interested in the disease, became alarmed. I was dispatched as a consultant public health ophthalmologist to the holding center for an on-site investigation.