266 research outputs found
Method and apparatus for determining time, direction, and composition of impacting space particles
A space particle collector for recording the time specific particles are captured, and its direction at the time of capture, utilizes an array of targets, each comprised of an MOS capacitor on a chip charged from an external source and discharged upon impact by a particle through a tab on the chip that serves as a fuse. Any impacting particle creates a crater, but only the first will cause a discharge of the capacitor. A substantial part of the metal film around the first crater is burned off by the discharge current. The time of the impulse which burns the tab, and the identification of the target, is recorded together with data from flight instruments. The metal film is partitioned into pie sections to provide a plurality of targets on each of an array of silicon wafers, thus increasing the total number of identified particles that can be collected. It is thus certain which particles were captured at what specific times
CU Comae: a new field double-mode RR Lyrae, the most metal poor discovered to date
We report the discovery of a new double-mode RR Lyrae variable (RRd) in the
field of our Galaxy: CU Comae. CU Comae is the sixth such RRd identified to
date and is the most metal-poor RRd ever detected. Based on BVI CCD photometry
spanning eleven years of observations, we find that CU Comae has periods
P0=0.5441641 +/-0.0000049d and P1=0.4057605 +/-0.0000018d. The amplitude of the
primary (first-overtone) period of CU Comae is about twice the amplitude of the
secondary (fundamental) period. The combination of the fundamental period of
pulsation P0 and the period ratio of P1/P0=0.7457 places the variable on the
metal-poor side of the Petersen diagram, in the region occupied by M68 and M15
RRd's. A mass of 0.83 solar masses is estimated for CU Comae using an updated
theoretical calibration of the Petersen diagram. High resolution spectroscopy
(R=30,000) covering the full pulsation cycle of CU Comae was obtained with the
2.7 m telescope of the Mc Donald Observatory, and has been used to build up the
radial velocity curve of the variable. Abundance analysis done on the four
spectra taken near minimum light (phase: 0.54 -- 0.71) confirms the metal poor
nature of CU Comae, for which we derive [Fe/H]=-2.38 +/-0.20. This value places
this new RRd at the extreme metal-poor edge of the metallicity distribution of
the RR Lyrae variables in our Galaxy.Comment: 21 pages including 8 Tables, Latex, 11 Figures. Accepted for
publication in The Astronomical Journal, October 2000 issu
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Determination of noble metals in Savannah River Site high-level radioactive sludge
High-level radioactive sludge at the Savannah River Site (SRS) will be processed at the Defense Waste Processing Facility (DWPF) into durable borosilicate glass wasteforms. The sludges are analyzed for elemental content before processing to ensure compatibility with the glass-making processes. Noble metal fission products in sludge, can under certain conditions, cause problems in the glass melter. Therefore, reliable noble metal determinations are important. The scheme used to measure noble metals in SRS sludges consists of dissolving sludge with hot aqua regia followed by determinations with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ICP-Mass Spectroscopy (ICP-MS) techniques. ICP-MS is the preferred method for measuring trace levels of noble metals in SRS radioactive waste because of superior sensitivity. Analytical results are presented for the two major types of SRS sludge
Measuring the impact of ambulatory red blood cell transfusion on home functional status: study protocol for a pilot randomized controlled trial
SPIRIT 2013: SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) Checklist for clinical trial protocols. (DOCX 65Â kb
Data sources and applied methods for paclitaxel safety signal discernment
Background Following the identification of a late mortality signal, the Food and Drug Administration (FDA) convened an advisory panel that concluded that additional clinical study data are needed to comprehensively evaluate the late mortality signal observed with the use of drug-coated balloons (DCB) and drug-eluting stent (DES). The objective of this review is to (1) identify and summarize the existing clinical and cohort studies assessing paclitaxel-coated DCBs and DESs, (2) describe and determine the quality of the available data sources for the evaluation of these devices, and (3) present methodologies that can be leveraged for proper signal discernment within available data sources. Methods Studies and data sources were identified through comprehensive searches. original research studies, clinical trials, comparative studies, multicenter studies, and observational cohort studies written in the English language and published from January 2007 to November 2021, with a follow-up longer than 36 months, were included in the review. Data quality of available data sources identified was assessed in three groupings. Moreover, accepted data-driven methodologies that may help circumvent the limitations of the extracted studies and data sources were extracted and described. Results There were 39 studies and data sources identified. This included 19 randomized clinical trials, nine single-arm studies, eight registries, three administrative claims, and electronic health records. Methodologies focusing on the use of existing premarket clinical data, the incorporation of all contributed patient time, the use of aggregated data, approaches for individual-level data, machine learning and artificial intelligence approaches, Bayesian approaches, and the combination of various datasets were summarized. Conclusion Despite the multitude of available studies over the course of eleven years following the first clinical trial, the FDA-convened advisory panel found them insufficient for comprehensively assessing the late-mortality signal. High-quality data sources with the capabilities of employing advanced statistical methodologies are needed to detect potential safety signals in a timely manner and allow regulatory bodies to act quickly when a safety signal is detected
Relationship Bonds and Customer Loyalty: A Study Across Different Service Contexts
The benefits of customer relationship strategies are well known and somewhat established nowadays. Customer loyalty emerges as the crucial glue in developing a relational approach. However, relational bonds, which relate to customer loyalty, have not yet been fully explored. Also, there is little research that takes into account the effect of service types on customer relationships and bonding. This paper develops a conceptual framework based on previous literature with a complete set of different relational bonds and examines its influence on customer loyalty across search, experience and credence services through a survey-based empirical study, with a sample of 233 consumers. The results provide guidance to managers to differentiate customer relationship strategies according to each specific service context
Investigating the Role of Islet Cytoarchitecture in Its Oscillation Using a New β-Cell Cluster Model
The oscillatory insulin release is fundamental to normal glycemic control. The basis of the oscillation is the intercellular coupling and bursting synchronization of β cells in each islet. The functional role of islet β cell mass organization with respect to its oscillatory bursting is not well understood. This is of special interest in view of the recent finding of islet cytoarchitectural differences between human and animal models. In this study we developed a new hexagonal closest packing (HCP) cell cluster model. The model captures more accurately the real islet cell organization than the simple cubic packing (SCP) cluster that is conventionally used. Using our new model we investigated the functional characteristics of β-cell clusters, including the fraction of cells able to burst fb, the synchronization index λ of the bursting β cells, the bursting period Tb, the plateau fraction pf, and the amplitude of intracellular calcium oscillation [Ca]. We determined their dependence on cluster architectural parameters including number of cells nβ, number of inter-β cell couplings of each β cell nc, and the coupling strength gc. We found that at low values of nβ, nc and gc, the oscillation regularity improves with their increasing values. This functional gain plateaus around their physiological values in real islets, at nβ∼100, nc∼6 and gc∼200 pS. In addition, normal β-cell clusters are robust against significant perturbation to their architecture, including the presence of non-β cells or dead β cells. In clusters with nβ>∼100, coordinated β-cell bursting can be maintained at up to 70% of β-cell loss, which is consistent with laboratory and clinical findings of islets. Our results suggest that the bursting characteristics of a β-cell cluster depend quantitatively on its architecture in a non-linear fashion. These findings are important to understand the islet bursting phenomenon and the regulation of insulin secretion, under both physiological and pathological conditions
Data sources and applied methods for paclitaxel safety signal discernment
BackgroundFollowing the identification of a late mortality signal, the Food and Drug Administration (FDA) convened an advisory panel that concluded that additional clinical study data are needed to comprehensively evaluate the late mortality signal observed with the use of drug-coated balloons (DCB) and drug-eluting stent (DES). The objective of this review is to (1) identify and summarize the existing clinical and cohort studies assessing paclitaxel-coated DCBs and DESs, (2) describe and determine the quality of the available data sources for the evaluation of these devices, and (3) present methodologies that can be leveraged for proper signal discernment within available data sources.MethodsStudies and data sources were identified through comprehensive searches. original research studies, clinical trials, comparative studies, multicenter studies, and observational cohort studies written in the English language and published from January 2007 to November 2021, with a follow-up longer than 36 months, were included in the review. Data quality of available data sources identified was assessed in three groupings. Moreover, accepted data-driven methodologies that may help circumvent the limitations of the extracted studies and data sources were extracted and described.ResultsThere were 39 studies and data sources identified. This included 19 randomized clinical trials, nine single-arm studies, eight registries, three administrative claims, and electronic health records. Methodologies focusing on the use of existing premarket clinical data, the incorporation of all contributed patient time, the use of aggregated data, approaches for individual-level data, machine learning and artificial intelligence approaches, Bayesian approaches, and the combination of various datasets were summarized.ConclusionDespite the multitude of available studies over the course of eleven years following the first clinical trial, the FDA-convened advisory panel found them insufficient for comprehensively assessing the late-mortality signal. High-quality data sources with the capabilities of employing advanced statistical methodologies are needed to detect potential safety signals in a timely manner and allow regulatory bodies to act quickly when a safety signal is detected
A conformação dos ecomuseus: elementos para compreensão e análise
Apresenta uma história dos ecomuseus enraizado nos movimentos de folclore e etnografia regional, do final do século XIX até os dias de hoje, examinando o caso francês. Explora aspectos em geral menos enfatizados neste campo, tal como a natureza e o papel atribuído aos acervos e ao patrimônio cultural e padrões museográticos
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