Design and construction of a Cherenkov imager for charge measurement of nuclear cosmic rays

A proximity focusing Cherenkov imager called CHERCAM, has been built for the charge measurement of nuclear cosmic rays with the CREAM instrument. It consists of a silica aerogel radiator plane across from a detector plane equipped with 1,600 1" diameter photomultipliers. The two planes are separated by a ring expansion gap. The Cherenkov light yield is proportional to the charge squared of the incident particle. The expected relative light collection accuracy is in the few percents range. It leads to an expected single element separation over the range of nuclear charge Z of main interest 1 < Z < 26. CHERCAM is designed to fly with the CREAM balloon experiment. The design of the instrument and the implemented technical solutions allowing its safe operation in high altitude conditions (radiations, low pressure, cold) are presented.Comment: 24 pages, 19 figure

Impact of particles on the Planck HFI detectors: Ground-based measurements and physical interpretation

The Planck High Frequency Instrument (HFI) surveyed the sky continuously from August 2009 to January 2012. Its noise and sensitivity performance were excellent, but the rate of cosmic ray impacts on the HFI detectors was unexpectedly high. Furthermore, collisions of cosmic rays with the focal plane produced transient signals in the data (glitches) with a wide range of characteristics. A study of cosmic ray impacts on the HFI detector modules has been undertaken to categorize and characterize the glitches, to correct the HFI time-ordered data, and understand the residual effects on Planck maps and data products. This paper presents an evaluation of the physical origins of glitches observed by the HFI detectors. In order to better understand the glitches observed by HFI in flight, several ground-based experiments were conducted with flight-spare HFI bolometer modules. The experiments were conducted between 2010 and 2013 with HFI test bolometers in different configurations using varying particles and impact energies. The bolometer modules were exposed to 23 MeV protons from the Orsay IPN TANDEM accelerator, and to $^{241}$Am and $^{244}$Cm $\alpha$-particle and $^{55}$Fe radioactive X-ray sources. The calibration data from the HFI ground-based preflight tests were used to further characterize the glitches and compare glitch rates with statistical expectations under laboratory conditions. Test results provide strong evidence that the dominant family of glitches observed in flight are due to cosmic ray absorption by the silicon die substrate on which the HFI detectors reside. Glitch energy is propagated to the thermistor by ballistic phonons, while there is also a thermal diffusion contribution. The implications of these results for future satellite missions, especially those in the far-infrared to sub-millimetre and millimetre regions of the electromagnetic spectrum, are discussed.Comment: 11 pages, 13 figure

Pattern and process in Amazon tree turnover, 1976-2001

Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests

Improved annotation of 3' untranslated regions and complex loci by combination of strand-specific direct RNA sequencing, RNA-seq and ESTs

The reference annotations made for a genome sequence provide the framework for all subsequent analyses of the genome. Correct annotation is particularly important when interpreting the results of RNA-seq experiments where short sequence reads are mapped against the genome and assigned to genes according to the annotation. Inconsistencies in annotations between the reference and the experimental system can lead to incorrect interpretation of the effect on RNA expression of an experimental treatment or mutation in the system under study. Until recently, the genome-wide annotation of 3-prime untranslated regions received less attention than coding regions and the delineation of intron/exon boundaries. In this paper, data produced for samples in Human, Chicken and A. thaliana by the novel single-molecule, strand-specific, Direct RNA Sequencing technology from Helicos Biosciences which locates 3-prime polyadenylation sites to within +/- 2 nt, were combined with archival EST and RNA-Seq data. Nine examples are illustrated where this combination of data allowed: (1) gene and 3-prime UTR re-annotation (including extension of one 3-prime UTR by 5.9 kb); (2) disentangling of gene expression in complex regions; (3) clearer interpretation of small RNA expression and (4) identification of novel genes. While the specific examples displayed here may become obsolete as genome sequences and their annotations are refined, the principles laid out in this paper will be of general use both to those annotating genomes and those seeking to interpret existing publically available annotations in the context of their own experimental dataComment: 44 pages, 9 figure

Выращивание из поликристаллического кремния солнечного качества квазимонокристаллических (mono-like) слитков методом направленной кристаллизации

In the frame of permanent objective to increase solar cell efficiency and to decrease production cost the monolike ingot process was designed which combine multicrystalline (mc) productivity and monocrystalline structure performances. As a raw material the mc-Solar Grade silicon (SoG-Si) was used because it is less expensive than the Si purified by gas chemical route (Siemens process or equivalent), Usage of the mc-SoG-Si for growing silicon ingots by monolike process should contribute to the ingot and wafer manufacturing cost decrease. SoG silicon using would be developed all the more fast since it enables to produce high efficiency solar cells. It is why the monolike process have been tested and optimized for Kazakhstan mc-SoG silicon. The objective of this work was study of the higher level content impurities influences on the crystal defect generation (mainly dislocations) of the monocrystalline structure. Visual monocrystalline structure, minority carrier lifetime mapping, and photoluminescence techniques were used to study the monolike ingots obtained from Kazakhstan’s mc-SoG silicon.В целях повышения эффективности солнечных элементов и снижение затрат на производство разработан процесс получения слитков кремния, по так называемой mono-like-технологии. Mono-like-процесс предназначен для получения монокристаллических слитков при использовании технологии производства мультикристаллического кремния (МК-Si). При этом в качестве сырья используют поликристаллический кремний (ПК-Si) «солнечного» качества (solar grade — SoG), технология получения которого является менее затратной, чем очистка кремния газохимическим процессом (Сименс-процесс или его эквивалент). Использование ПК-Si SoG для выращивания слитков по mono-like технологии должно способствовать снижению затрат на получение слитков и пластин. Новые технологии производства солнечных элементов, использующие ПК-Si SoG, разрабатываются быстрыми темпами, так как это позволяет производить при меньших затратах солнечные элементы с достаточно высоким КПД. Именно поэтому mono-like-процесс апробирован и оптимизирован для казахстанского ПК-Si SoG. Изучено влияние более высокой концентрации примесей в ПК-Si SoG на образование кристаллических дефектов (главным образом дислокаций) в монокристаллических структурах. Для исследования свойств mono-like слитка, полученного в промышленных масштабах из казахстанского ПК-Si SoG, использованы визуализация монокристаллической структуры, картирование времени жизни неосновных носителей заряда и фотолюминесценция

Surrogate endpoints for overall survival in digestive oncology trials: which candidates? A questionnaires survey among clinicians and methodologists

<p>Abstract</p> <p>Background</p> <p>Overall survival (OS) is the gold standard for the demonstration of a clinical benefit in cancer trials. Replacement of OS by a surrogate endpoint allows to reduce trial duration. To date, few surrogate endpoints have been validated in digestive oncology. The aim of this study was to draw up an ordered list of potential surrogate endpoints for OS in digestive cancer trials, by way of a survey among clinicians and methodologists. Secondary objective was to obtain their opinion on surrogacy and quality of life (QoL).</p> <p>Methods</p> <p>In 2007 and 2008, self administered sequential questionnaires were sent to a panel of French clinicians and methodologists involved in the conduct of cancer clinical trials. In the first questionnaire, panellists were asked to choose the most important characteristics defining a surrogate among six proposals, to give advantages and drawbacks of the surrogates, and to answer questions about their validation and use. Then they had to suggest potential surrogate endpoints for OS in each of the following tumour sites: oesophagus, stomach, liver, pancreas, biliary tract, lymphoma, colon, rectum, and anus. They finally gave their opinion on QoL as surrogate endpoint. In the second questionnaire, they had to classify the previously proposed candidate surrogates from the most (position #1) to the least relevant in their opinion.</p> <p>Frequency at which the endpoints were chosen as first, second or third most relevant surrogates was calculated and served as final ranking.</p> <p>Results</p> <p>Response rate was 30% (24/80) in the first round and 20% (16/80) in the second one. Participants highlighted key points concerning surrogacy. In particular, they reminded that a surrogate endpoint is expected to predict clinical benefit in a well-defined therapeutic situation. Half of them thought it was not relevant to study QoL as surrogate for OS.</p> <p>DFS, in the neoadjuvant settings or early stages, and PFS, in the non operable or metastatic settings, were ranked first, with a frequency of more than 69% in 20 out of 22 settings. PFS was proposed in association with QoL in metastatic primary liver and stomach cancers (both 81%). This composite endpoint was ranked second in metastatic oesophageal (69%), colorectal (56%) and anal (56%) cancers, whereas QoL alone was also suggested in most metastatic situations.</p> <p>Other endpoints frequently suggested were R0 resection in the neoadjuvant settings (oesophagus (69%), stomach (56%), pancreas (75%) and biliary tract (63%)) and response. An unexpected endpoint was metastatic PFS in non operable oesophageal (31%) and pancreatic (44%) cancers. Quality and results of surgical procedures like sphincter preservation were also cited as eligible surrogate endpoints in rectal (19%) and anal (50% in case of localized disease) cancers. Except for alpha-FP kinetic in hepatocellular carcinoma (13%) and CA19-9 decline (6%) in pancreas, few endpoints based on biological or tumour markers were proposed.</p> <p>Conclusion</p> <p>The overall results should help prioritise the endpoints to be statistically evaluated as surrogate for OS, so that trialists and clinicians can rely on endpoints that ensure relevant clinical benefit to the patient.</p

ОПТИМИЗАЦИЯ УРОВНЯ ЛЕГИРОВАНИЯ КРЕМНИЯ «СОЛНЕЧНОГО» КАЧЕСТВА ДЛЯ ПОВЫШЕНИЯ ПРИГОДНОГО ОБЪЕМА СЛИТКОВ И КПД СОЛНЕЧНЫХ ЭЛЕМЕНТОВ

In the close future, use of SoG should become prominent for photovoltaic ingot production as it requires much less energy for purification compared to Silicon grades using gas transformation and purification (usually Siemens process or equivalent also used for electronic−grade preparation). During this study, several kinds of silicon were compared with different rates of dopant content (mainly boron and phosphorus). Ingot yield and cell efficiency were optimized for each source of silicon at a production level (450 kg ingots) using boron or gallium doping. Starting from the resistivity specification given by the cell process, the doping level was adjusted in order to maximize the ingot silicon yield (weight of silicon bricks used for wafer cutting/ weight of Silicon ingot). After doping adjustment, ingot quality was checked: brick resistivity, lifetime of minority carriers and wafers were processed into solar cells. Optimizing of doping led to get comparable ingot yields and cell efficiencies using SoG and silicon purified by Siemens process or equivalent. The study was implemented at Kazakhstan Solar Silicon plant in Ust−Kamenogorsk using Kazakhstan SoG, SoG from a European manufacturer and polycrystalline Silicon purified by Siemens process. Directional solidification furnaces were manufactured by the French company ECM Technologies.В ближайшем будущем поликристаллический кремний (ПК) «солнечного» качества (SoG) станет основным материалом для выращивания слитков мультикристаллического кремния (МКК), предназначенных для фотовольтаического (ФВ) производства, так как требует гораздо меньше энергии для очистки по сравнению с ПК, полученным в Сименс−процессе (ПК электронного качества).Рассмотрено несколько видов ПК с различным уровнем содержания примесей (преимущественно бора и фосфора). Для каждого из этих видов ПК при выращивании их них слитков МКК в промышленном масштабе с использованием примесей бора и галлия оптимизированы выход годного кремния и эффективность солнечных элементов. Уровень легирования рассчитан таким образом, чтобы увеличить выход годного кремния из слитка МКК. После получения слитков проверено их качество (изменение удельного сопротивления по высоте кремниевых блоков, время жизни неосновных носителей заряда) и затем из пластин созданы солнечные элементы. За счет оптимизации уровня легирования выращены сопоставимые по выходу годного кремния слитки МКК из ПК SoG и ПК, полученного Сименс− процессом, а также изготовлены солнечные элементы, сопостовимые по эффективности преобразования солнечной энергии (КПД).Исследование проведено на заводе Kazakhstan Solar Silicon в Усть−Каменогорске, с применением казахстанского и европейского ПК SoG, а также ПК, полученного Сименс− процессом. Печи для направленной кристаллизации для выращивания МКК изготовлены французской компанией ECM Technologies

Troublesome Heterotopic Ossification after Central Nervous System Damage: A Survey of 570 Surgeries

BACKGROUND: Heterotopic ossification (HO) is a frequent complication after central nervous system (CNS) damage but has seldom been studied. We aimed to investigate features of HO for the first time in a large sample and the rate of early recurrence of HO in terms of the time of surgery. METHODOLOGY/PRINCIPAL FINDINGS: We retrospectively analyzed data from an anonymous prospective survey of patients undergoing surgery between May 1993 and November 2009 in our institution for troublesome HO related to acquired neurological disease. Demographic and HO characteristics and neurological etiologies were recorded. For 357 consecutive patients, we collected data on 539 first surgeries for HO (129 surgeries for multiple sites). During the follow-up, recurrences requiring another surgery appeared in 31 cases (5.8% [31/539]; 95% confidence interval [CI]: 3.8%-7.8%; 27 patients). Most HO requiring surgery occurred after traumatic brain injury (199 patients [55.7%]), then spinal cord injury (86 [24.0%]), stroke (42 [11.8%]) and cerebral anoxia (30 [8.6%]). The hip was the primary site of HO (328 [60.9%]), then the elbow (115 [21.3%]), knee (77 [14.3%]) and shoulder (19 [3.5%]). For all patients, 181 of the surgeries were performed within the first year after the CNS damage, without recurrence of HO. Recurrence was not associated with etiology (p = 0.46), sex (p = 1.00), age at CNS damage (p = 0.2), multisite localization (p = 0.34), or delay to surgery (p = 0.7). CONCLUSIONS/SIGNIFICANCE: In patients with CNS damage, troublesome HO and recurrence occurs most frequently after traumatic brain injury and appears frequently in the hip and elbow. Early surgery for HO is not a factor of recurrence

The Intestinal Microbiota Plays a Role in Salmonella-Induced Colitis Independent of Pathogen Colonization

The intestinal microbiota is composed of hundreds of species of bacteria, fungi and protozoa and is critical for numerous biological processes, such as nutrient acquisition, vitamin production, and colonization resistance against bacterial pathogens. We studied the role of the intestinal microbiota on host resistance to Salmonella enterica serovar Typhimurium-induced colitis. Using multiple antibiotic treatments in 129S1/SvImJ mice, we showed that disruption of the intestinal microbiota alters host susceptibility to infection. Although all antibiotic treatments caused similar increases in pathogen colonization, the development of enterocolitis was seen only when streptomycin or vancomycin was used; no significant pathology was observed with the use of metronidazole. Interestingly, metronidazole-treated and infected C57BL/6 mice developed severe pathology. We hypothesized that the intestinal microbiota confers resistance to infectious colitis without affecting the ability of S. Typhimurium to colonize the intestine. Indeed, different antibiotic treatments caused distinct shifts in the intestinal microbiota prior to infection. Through fluorescence in situ hybridization, terminal restriction fragment length polymorphism, and real-time PCR, we showed that there is a strong correlation between the intestinal microbiota composition before infection and susceptibility to Salmonella-induced colitis. Members of the Bacteroidetes phylum were present at significantly higher levels in mice resistant to colitis. Further analysis revealed that Porphyromonadaceae levels were also increased in these mice. Conversely, there was a positive correlation between the abundance of Lactobacillus sp. and predisposition to colitis. Our data suggests that different members of the microbiota might be associated with S. Typhimurium colonization and colitis. Dissecting the mechanisms involved in resistance to infection and inflammation will be critical for the development of therapeutic and preventative measures against enteric pathogens