471 research outputs found
Effect of delayed acquisition times on Gadolinium-enhanced MRI of the presumably normal canine brain
A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10 minute delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable CSF. Specific ROIs were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement greater than 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve and the trigeminal nerve root. Structures with an active blood-brain-barrier had minimal contrast enhancement (<6%). Enhancing structures had significantly more contrast enhancement at t=1min versus t=10min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Inter-observer agreement was moderate to good in favor of the initial post contrast T1w sequence. The observers found either no difference or poor agreement in identification of the non-vascular structures. Intra-observer agreement was very good with all vascular structures and most non-vascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w post contrast sequence is preferable but not essential should a delayed post contrast T1w sequence be performed
Formal Concept Lattice Representations and Algorithms for Hypergraphs
There is increasing focus on analyzing data represented as hypergraphs, which
are better able to express complex relationships amongst entities than are
graphs. Much of the critical information about hypergraph structure is
available only in the intersection relationships of the hyperedges, and so
forming the "intersection complex" of a hypergraph is quite valuable. This
identifies a valuable isomorphism between the intersection complex and the
"concept lattice" formed from taking the hypergraph's incidence matrix as a
"formal context": hypergraphs also generalize graphs in that their incidence
matrices are arbitrary Boolean matrices. This isomorphism allows connecting
discrete algorithms for lattices and hypergraphs, in particular s-walks or
s-paths on hypergraphs can be mapped to order theoretical operations on the
concept lattice. We give new algorithms for formal concept lattices and
hypergraph s-walks on concept lattices. We apply this to a large real-world
dataset and find deep lattices implying high interconnectivity and complex
geometry of hyperedges
A comparison of fragmenting lead-based and lead-free bullets for aerial shooting of wild pigs
In response to the health threats posed by toxic lead to humans, scavenging wildlife and the environment, there is currently a focus on transitioning from lead-based to lead-free bullets for shooting of wild animals. We compared efficiency metrics and terminal ballistic performance for lead-based and lead-free (non-lead) bullets for aerial shooting of wild pigs (Sus scrofa) in eastern Australia. Ballistic testing revealed that lead-based and lead-free bullets achieved similar performance in precision and muzzle kinetic energy (E-0) levels (3337.2 J and 3345.7 J, respectively). An aerial shooting trial was conducted with wild pigs shot with one type of lead-based and one type of lead-free bullets under identical conditions. Observations were made from 859 shooting events (n = 430 and 429 respectively), with a sub-set of pigs examined via gross post-mortem (n = 100 and 108 respectively), and a further sub-set examined via radiography (n = 94 and 101 respectively). The mean number of bullets fired per pig killed did not differ greatly between lead-based and lead-free bullets respectively (4.09 vs 3.91), nor did the mean number of bullet wound tracts in each animal via post-mortem inspection (3.29 vs 2.98). However, radiography revealed a higher average number of fragments per animal (median >300 vs median = 55) and a broader distribution of fragments with lead-based bullets. Our results suggest that lead-based and lead-free bullets are similarly effective for aerial shooting of wild pigs, but that the bullet types behave differently, with lead-based bullets displaying a higher degree of fragmentation. These results suggest that aerial shooting may be a particularly important contributor to scavenging wildlife being exposed to lead and that investigation of lead-free bullets for this use should continue
Hypergraph Topological Features for Autoencoder-Based Intrusion Detection for Cybersecurity Data
In this position paper, we argue that when hypergraphs are used to capture
multi-way local relations of data, their resulting topological features
describe global behaviour. Consequently, these features capture complex
correlations that can then serve as high fidelity inputs to autoencoder-driven
anomaly detection pipelines. We propose two such potential pipelines for
cybersecurity data, one that uses an autoencoder directly to determine network
intrusions, and one that de-noises input data for a persistent homology system,
PHANTOM. We provide heuristic justification for the use of the methods
described therein for an intrusion detection pipeline for cyber data. We
conclude by showing a small example over synthetic cyber attack data
Medical Mistrust, Racism, and Delays in Preventive Health Screening Among African-American Men
The contribution of medical mistrust to healthcare utilization delays has gained increased public health attention. However, few studies examine these associations among African-American men, who delay preventive healthcare more often and report higher levels of medical mistrust than non-Hispanic White men. Additionally, studies rarely account for other factors reportedly working in tandem with medical mistrust to increase African-American men’s preventive health screening delays (i.e., everyday racism and perceived racism in healthcare). We examined associations between medical mistrust, perceived racism in healthcare, everyday racism, and preventive health screening delays. Analyses were conducted using cross-sectional data from 610 African-American men aged 20 years and older recruited primarily from barbershops in four US regions (2003–2009). Independent variables were medical mistrust (MM), everyday racism (ER), and perceived racism in healthcare (PRH). Dependent variables were self-reported routine checkup, blood pressure screening, and cholesterol screening delays. Using multiple logistic regression and tests for mediation, we calculated odds ratios and 95% confidence intervals to assess associations between the independent and dependent variables. After final adjustment, African-American men with higher MM were significantly more likely to delay blood pressure screenings. Men with more frequent ER exposure were significantly more likely to delay routine checkups and blood pressure screenings. Higher levels of PRH were associated with a significant increased likelihood of delaying cholesterol screening. MM did not mediate associations between ER and screening delays. Increasing preventive health screening among African-American men requires addressing medical mistrust and racism in and outside healthcare institutions
Stepping out of Flatland: Discovering Behavior Patterns as Topological Structures in Cyber Hypergraphs
Data breaches and ransomware attacks occur so often that they have become
part of our daily news cycle. This is due to a myriad of factors, including the
increasing number of internet-of-things devices, shift to remote work during
the pandemic, and advancement in adversarial techniques, which all contribute
to the increase in both the complexity of data captured and the challenge of
protecting our networks. At the same time, cyber research has made strides,
leveraging advances in machine learning and natural language processing to
focus on identifying sophisticated attacks that are known to evade conventional
measures. While successful, the shortcomings of these methods, particularly the
lack of interpretability, are inherent and difficult to overcome. Consequently,
there is an ever-increasing need to develop new tools for analyzing cyber data
to enable more effective attack detection. In this paper, we present a novel
framework based in the theory of hypergraphs and topology to understand data
from cyber networks through topological signatures, which are both flexible and
can be traced back to the log data. While our approach's mathematical grounding
requires some technical development, this pays off in interpretability, which
we will demonstrate with concrete examples in a large-scale cyber network
dataset. These examples are an introduction to the broader possibilities that
lie ahead; our goal is to demonstrate the value of applying methods from the
burgeoning fields of hypernetwork science and applied topology to understand
relationships among behaviors in cyber data.Comment: 18 pages, 11 figures. This paper is written for a general audienc
Efficacy and Safety of Adalimumab in Conjunction With Surgery in Moderate to Severe Hidradenitis Suppurativa:The SHARPS Randomized Clinical Trial
IMPORTANCE: Surgery is a mainstay in the management of hidradenitis suppurativa (HS). Adalimumab is the first drug approved for HS. OBJECTIVE: To investigate the efficacy and safety of adalimumab in combination with wide-excision surgery followed by secondary intention healing. DESIGN, SETTING, AND PARTICIPANTS: The Safety and Efficacy of Adalimumab for Hidradenitis Suppurativa Peri-Surgically (SHARPS) trial was a phase 4, randomized, double-blind, placebo-controlled study of adalimumab in conjunction with surgery. Patients were enrolled in 45 sites across 20 countries from July 18, 2016, to February 2, 2019, with the last patient visit on October 16, 2019. Eligible patients (aged 18-65 years) had moderate to severe HS that required radical surgery in an axillary or inguinal region and had 2 other anatomical regions affected, with 1 or more regions at Hurley stage II or III. Analysis was conducted in November 2019. INTERVENTIONS: Patients were randomized 1:1 to receive continuous adalimumab, 40 mg, or placebo during presurgery (12 weeks), perioperative (2 weeks), and postoperative (10 weeks) periods. MAIN OUTCOMES AND MEASURES: The primary end point was the proportion of patients achieving HS clinical response across all body regions at week 12. RESULTS: Overall, 103 patients were randomized to adalimumab and 103 to matching placebo. Among all patients, 51% (n = 106) were women, 94% (n = 193) were White, and the mean (SD) age was 37.6 (11.3) years. At week 12, significantly more patients receiving adalimumab (49 of 103 [48%]) vs placebo (35 of 103 [34%]; P = .049) achieved HS clinical response across all body regions (treatment difference, 14% [95% CI, 0%-27%]). Treatment-emergent adverse events were reported in 74 of 103 patients (72%) and 69 of 103 patients (67%) in the adalimumab and placebo groups, respectively. No increased risk of postoperative wound infection, complication, or hemorrhage was observed with adalimumab vs placebo. Two deaths occurred in the adalimumab group; neither was considered as having a reasonable possibility of relationship to study drug. CONCLUSIONS AND RELEVANCE: Adalimumab was efficacious in conjunction with wide-excision surgery followed by secondary intention healing, with no need to interrupt treatment prior to surgery. These data support further investigation of adalimumab as an adjuvant therapy to surgery in patients with moderate to severe HS. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT0280897
SSWAP: A Simple Semantic Web Architecture and Protocol for semantic web services
<p>Abstract</p> <p>Background</p> <p>SSWAP (<b>S</b>imple <b>S</b>emantic <b>W</b>eb <b>A</b>rchitecture and <b>P</b>rotocol; pronounced "swap") is an architecture, protocol, and platform for using reasoning to semantically integrate heterogeneous disparate data and services on the web. SSWAP was developed as a hybrid semantic web services technology to overcome limitations found in both pure web service technologies and pure semantic web technologies.</p> <p>Results</p> <p>There are currently over 2400 resources published in SSWAP. Approximately two dozen are custom-written services for QTL (Quantitative Trait Loci) and mapping data for legumes and grasses (grains). The remaining are wrappers to Nucleic Acids Research Database and Web Server entries. As an architecture, SSWAP establishes how clients (users of data, services, and ontologies), providers (suppliers of data, services, and ontologies), and discovery servers (semantic search engines) interact to allow for the description, querying, discovery, invocation, and response of semantic web services. As a protocol, SSWAP provides the vocabulary and semantics to allow clients, providers, and discovery servers to engage in semantic web services. The protocol is based on the W3C-sanctioned first-order description logic language OWL DL. As an open source platform, a discovery server running at <url>http://sswap.info</url> (as in to "swap info") uses the description logic reasoner Pellet to integrate semantic resources. The platform hosts an interactive guide to the protocol at <url>http://sswap.info/protocol.jsp</url>, developer tools at <url>http://sswap.info/developer.jsp</url>, and a portal to third-party ontologies at <url>http://sswapmeet.sswap.info</url> (a "swap meet").</p> <p>Conclusion</p> <p>SSWAP addresses the three basic requirements of a semantic web services architecture (<it>i.e</it>., a common syntax, shared semantic, and semantic discovery) while addressing three technology limitations common in distributed service systems: <it>i.e</it>., <it>i</it>) the fatal mutability of traditional interfaces, <it>ii</it>) the rigidity and fragility of static subsumption hierarchies, and <it>iii</it>) the confounding of content, structure, and presentation. SSWAP is novel by establishing the concept of a canonical yet mutable OWL DL graph that allows data and service providers to describe their resources, to allow discovery servers to offer semantically rich search engines, to allow clients to discover and invoke those resources, and to allow providers to respond with semantically tagged data. SSWAP allows for a mix-and-match of terms from both new and legacy third-party ontologies in these graphs.</p
Brangus cows have ovarian reserve parameters more like Brahman than Angus cows
Bos indicus females have more surface antral follicles than Bos taurus females; however, histological studies demonstrated no difference in total number of primordial follicles between these two biological types of cattle. Primordial follicle density in the ovary was less in Nelore ovaries compared to Angus ovaries, but no studies have examined the primordial follicle density in Bos indicus cross-bred females. It, therefore, was hypothesized that primordial follicle density in the ovary would decrease as percentage Bos indicus increased. Ovaries were collected from cross-bred Angus (n=32, no Bos indicus influence), Brangus (n=15), or Brahman (n=9) cows and prepared for histological evaluation. There was no difference in total number of primordial follicles per ovary between breeds (P \u3e 0.10). When numbers of primordial follicles were expressed on a per gram of ovarian tissue basis, there were fewer primordial follicles per gram of ovarian tissue in Brangus and Brahman cows than in Angus cows (P \u3c 0.05). Brangus cows did not differ from Brahman cows in primordial follicle density (P \u3e 0.10). Differences in primordial follicle density could indicate differences in capacity of ovarian stroma to produce factors necessary for oogonial proliferation and primordial follicle formation among breeds. Identifying these factors could improve the aprroach for culturing pre-antral follicles of cattle. Furthermore, these results explain why ultrasonographic antral follicle counts may need to be adjusted to a greater threshold to predict size of the ovarian reserve and determine ovarian reserve related reproductive traits in Bos indicus females
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