62 research outputs found
Low energy proton capture study of the [14]N(p,Îł)[15]O reaction
The 14N(p, Îł)15O reaction regulates the rate of energy production for stars slightly more massive than the sun throughout stable hydrogen burning on the main sequence. The 14N(p, Îł)15O reaction rate also determines the luminosity for all stars after leaving the main sequence when their cores have exhausted hydrogen fuel, and later when they become red giant stars. The significant role that this reaction plays in stellar evolution has far-reaching consequences, from neutrino production in our Sun, to age estimates of globular clusters in our Galaxy. The weak cross section and inherent coincidence summing in the 15O Îł-ray decay scheme make a precision measurement of the astrophysical S-factor especially challenging, particularly for the ground-state transition. The present study, performed in the Laboratory for Experimental Nuclear Astrophysics (LENA), was aimed at measuring the ground-state transition at low energy by utilizing a new 24-element, position-sensitive, NaI(Tl) detector array. Because the array is highly segmented, the 14N(p, Îł)15O S-factor was evaluated for transitions to the ground, 5.18, 6.18, and 6.79MeV states without the need for coincidence summing corrections. Additionally, the positionsensitivity of the detector was exploited to measure the angular correlation of the two-photon cascades. Software cuts were made to the data in order to identify single and coincident Îł-ray events and a fraction fit analysis technique was used to extract the characteristic 15O peaks from the composite Îł-ray spectrum. The results from the current work demonstrated a new approach to measuring weak nuclear cross sections near astrophysically relevant energies that, with refinements, has broader applications in Îł-ray spectroscopy.Doctor of Philosoph
The LEAP Gamma-Ray Burst Polarimeter for the International Space Station
No abstract availabl
Case report: Case series featuring anastomotic colonic adenocarcinoma following jejunoileal bypass requiring oncologic resection and jejunoileal bypass reversal
Like all surgical fields, bariatric surgery has evolved immensely, so much so that previous procedures are now obsolete. For instance, the jejunoileal bypass has fallen out of favor after severe metabolic consequences resulted in prolonged morbidity and even mortality. Despite this, several patients persevered long enough to develop other pathology, such as cancer. This progression has been validated in animal models but not human patients. Nonetheless, contemporary surgeons may encounter situations where they must resect and re-establish intestinal continuity in patients with this antiquated anatomy. When faced with this scenario, the question of whether or not the previously bypassed small bowel can be safely reunited plagues the surgeon remains unanswered. Unfortunately, the literature does not effectively answer this question, even anecdotally through case reports or series. Therefore, we share our experience with three patients who developed colon cancer following jejunoileal bypass and subsequently underwent oncologic resection with simultaneous reversal of their jejunoileal bypasses
Observational study of visual testing efficacy in detecting cannabis usage
Drug recognition and examination programs are widely used to detect drug impairment in motor vehicle operators. Visual tests are a key assessment in the detection of cannabis-related impairment. Participants were recruited via social media from the medical cannabis community in Southwestern Ontario, Canada. Twenty-two participants completed the full observational trial design. The majority (n = 13 or 59.1%) were male, with a mean age of 36 years (SD = 9.4; range: 24â59). Participants underwent the following protocol: 1) First round of testing (vital signs, bio sample collection, visual tests, subjective data, neurocognitive testing) (Baseline phase); 2) Consumption of cannabis via inhalation; 3) Second round of testing 30 minutes following consumption (THC phase); 4) Additional rounds of testing at 90, 150, and 210 minutes following consumption (Recovery phase). Visual assessment data and vital signs did not follow typical patterns associated with acute cannabis intoxication. With blood THC levels more than double the Canadian legal limit (5 ng/mL), visual testing results were not diagnostic for cannabis impairment, as participants maintained normal pupil sizes and normal ocular convergence patterns. Visual testing is a key component in standardized examinations used for detecting cannabis-related impairment in Canadian drivers; however, our data indicate that visual testing may not be an effective diagnostic tool for the specific population of medical cannabis users
Zero Botnets: An Observe-Pursue-Counter Approach
Adversarial Internet robots (botnets) represent a growing threat to the safe
use and stability of the Internet. Botnets can play a role in launching
adversary reconnaissance (scanning and phishing), influence operations
(upvoting), and financing operations (ransomware, market manipulation, denial
of service, spamming, and ad click fraud) while obfuscating tailored tactical
operations. Reducing the presence of botnets on the Internet, with the
aspirational target of zero, is a powerful vision for galvanizing policy
action. Setting a global goal, encouraging international cooperation, creating
incentives for improving networks, and supporting entities for botnet takedowns
are among several policies that could advance this goal. These policies raise
significant questions regarding proper authorities/access that cannot be
answered in the abstract. Systems analysis has been widely used in other
domains to achieve sufficient detail to enable these questions to be dealt with
in concrete terms. Defeating botnets using an observe-pursue-counter
architecture is analyzed, the technical feasibility is affirmed, and the
authorities/access questions are significantly narrowed. Recommended next steps
include: supporting the international botnet takedown community, expanding
network observatories, enhancing the underlying network science at scale,
conducting detailed systems analysis, and developing appropriate policy
frameworks.Comment: 26 pages, 13 figures, 2 tables, 72 references, submitted to PlosOn
Analysis of Salmonella enterica Serotype Paratyphi A Gene Expression in the Blood of Bacteremic Patients in Bangladesh
Salmonella enterica serotype Paratyphi A is a significant and emerging global public health problem and accounts for one fifth of all cases of enteric fever in many areas of Asia. S. Paratyphi A only infects humans, and the lack of an appropriate animal model has limited the study of S. Paratyphi A infection. In this study, we report the application of an RNA analysis method, Selective Capture of Transcribed Sequences (SCOTS), to evaluate which S. Paratyphi A genes are expressed directly in the blood of infected humans. Our results provide insight into the bacterial adaptations and modifications that S. Paratyphi A may need to survive within infected humans and suggest that similar approaches may be applied to other pathogens in infected humans and animals
Comparative Proteomic Analysis of the PhoP Regulon in Salmonella enterica Serovar Typhi Versus Typhimurium
Background: S. Typhi, a human-restricted Salmonella enterica serovar, causes a systemic intracellular infection in humans (typhoid fever). In comparison, S. Typhimurium causes gastroenteritis in humans, but causes a systemic typhoidal illness in mice. The PhoP regulon is a well studied two component (PhoP/Q) coordinately regulated network of genes whose expression is required for intracellular survival of S. enterica. Methodology/Principal Findings: Using high performance liquid chromatography mass spectrometry (HPLC-MS/MS), we examined the protein expression profiles of three sequenced S. enterica strains: S. Typhimurium LT2, S. Typhi CT18, and S. Typhi Ty2 in PhoP-inducing and non-inducing conditions in vitro and compared these results to profiles of mutants derived from S. Typhimurium LT2 and S. Typhi Ty2. Our analysis identified 53 proteins in S. Typhimurium LT2 and 56 proteins in S. Typhi that were regulated in a PhoP-dependent manner. As expected, many proteins identified in S. Typhi demonstrated concordant differential expression with a homologous protein in S. Typhimurium. However, three proteins (HlyE, STY1499, and CdtB) had no homolog in S. Typhimurium. HlyE is a pore-forming toxin. STY1499 encodes a stably expressed protein of unknown function transcribed in the same operon as HlyE. CdtB is a cytolethal distending toxin associated with DNA damage, cell cycle arrest, and cellular distension. Gene expression studies confirmed up-regulation of mRNA of HlyE, STY1499, and CdtB in S. Typhi in PhoP-inducing conditions. Conclusions/Significance: This study is the first protein expression study of the PhoP virulence associated regulon using strains of Salmonella mutant in PhoP, has identified three Typhi-unique proteins (CdtB, HlyE and STY1499) that are not present in the genome of the wide host-range Typhimurium, and includes the first protein expression profiling of a live attenuated bacterial vaccine studied in humans (Ty800)
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
Play, Learn, and Teach OutdoorsâNetwork (PLaTO-Net): terminology, taxonomy, and ontology
Background: A recent dialogue in the feld of play, learn, and teach outdoors (referred to as âPLaTOâ hereafter) demonstrated the need for developing harmonized and consensus-based terminology, taxonomy, and ontology for PLaTO. This is important as the feld evolves and diversifes in its approaches, contents, and contexts over time and in diferent countries, cultures, and settings. Within this paper, we report the systematic and iterative processes underâtaken to achieve this objective, which has built on the creation of the global PLaTO-Network (PLaTO-Net).
Methods: This project comprised of four major methodological phases. First, a systematic scoping review was conducted to identify common terms and defnitions used pertaining to PLaTO. Second, based on the results of the scoping review, a draft set of key terms, taxonomy, and ontology were developed, and shared with PLaTO members, who provided feedback via four rounds of consultation. Third, PLaTO terminology, taxonomy, and ontology were then fnalized based on the feedback received from 50 international PLaTO member participants who responded toâ„3 rounds of the consultation survey and dialogue. Finally, eforts to share and disseminate project outcomes were made through diferent online platforms.
Results: This paper presents the fnal defnitions and taxonomy of 31 PLaTO terms along with the PLaTO-Net ontolâogy model. The model incorporates other relevant concepts in recognition that all the aspects of the model are interrelated and interconnected. The fnal terminology, taxonomy, and ontology are intended to be applicable to, and relevant for, all people encompassing various identities (e.g., age, gender, culture, ethnicity, ability).
Conclusions: This project contributes to advancing PLaTO-based research and facilitating intersectoral and interâdisciplinary collaboration, with the long-term goal of fostering and strengthening PLaTOâs synergistic linkages with healthy living, environmental stewardship, climate action, and planetary health agendas. Notably, PLaTO terminology, taxonomy and ontology will continue to evolve, and PLaTO-Net is committed to advancing and periodically updating harmonized knowledge and understanding in the vast and interrelated areas of PLaTO
A multimodal cell census and atlas of the mammalian primary motor cortex
ABSTRACT We report the generation of a multimodal cell census and atlas of the mammalian primary motor cortex (MOp or M1) as the initial product of the BRAIN Initiative Cell Census Network (BICCN). This was achieved by coordinated large-scale analyses of single-cell transcriptomes, chromatin accessibility, DNA methylomes, spatially resolved single-cell transcriptomes, morphological and electrophysiological properties, and cellular resolution input-output mapping, integrated through cross-modal computational analysis. Together, our results advance the collective knowledge and understanding of brain cell type organization: First, our study reveals a unified molecular genetic landscape of cortical cell types that congruently integrates their transcriptome, open chromatin and DNA methylation maps. Second, cross-species analysis achieves a unified taxonomy of transcriptomic types and their hierarchical organization that are conserved from mouse to marmoset and human. Third, cross-modal analysis provides compelling evidence for the epigenomic, transcriptomic, and gene regulatory basis of neuronal phenotypes such as their physiological and anatomical properties, demonstrating the biological validity and genomic underpinning of neuron types and subtypes. Fourth, in situ single-cell transcriptomics provides a spatially-resolved cell type atlas of the motor cortex. Fifth, integrated transcriptomic, epigenomic and anatomical analyses reveal the correspondence between neural circuits and transcriptomic cell types. We further present an extensive genetic toolset for targeting and fate mapping glutamatergic projection neuron types toward linking their developmental trajectory to their circuit function. Together, our results establish a unified and mechanistic framework of neuronal cell type organization that integrates multi-layered molecular genetic and spatial information with multi-faceted phenotypic properties
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