Counting nonsingular matrices with primitive row vectors

We give an asymptotic expression for the number of nonsingular integer n-by-n-matrices with primitive row vectors, determinant k, and Euclidean matrix norm less than T, for large T. We also investigate the density of matrices with primitive rows in the space of matrices with determinant k, and determine its asymptotics for large k.Comment: 21 pages. Fixed proof of monotonicity of the density function. Added a result on the image of the density functio

The number of points from a random lattice that lie inside a ball

We prove a sharp bound for the remainder term of the number of lattice points inside a ball, when averaging over a compact set of (not necessarily unimodular) lattices, in dimensions two and three. We also prove that such a bound cannot hold if one averages over the space of all lattices.Comment: 29 page

Aging and Weight-Ratio Estimation

Many researchers have explored the way younger people perceive weight ratios using a variety of methodologies; however, very few researchers have used a more direct ratio estimation procedure, in which participants estimate an actual ratio between two or more weights. Of the few researchers who have used a direct method, the participants who were recruited were invariably younger adults. To date, there has been no research performed to examine how older adults perceive weight-ratios, using direct estimation or any other technique. Past research has provided evidence that older adults have more difficulty than younger adults in perceiving small differences in weight (i.e., the difference threshold for older adults is higher than that of younger adults). Given this result, one might expect that older adults would demonstrate similar impairments in weight ratio estimation compared to younger adults. The current experiment compared the abilities of 17 younger and 17 older adults to estimate weight ratios, using a direct ratio estimation procedure. On any given trial, participants were presented with two weights, and were asked to provide a direct estimate of the ratio, with the heavier in relation to the lighter. The results showed that the participants’ perceived weight ratios increased as a linear function of the actual weight ratios and that compared to younger adults, the older adults overestimated the weight ratios. The age-related overestimation was especially pronounced at higher weight ratios

Predictors for cerebral edema in acute ischemic stroke treated with intravenous thrombolysis

Cerebral edema (CED) is a severe complication of acute ischemic stroke. There is uncertainty regarding the predictors for the development of CED after cerebral infarction. We aimed to determine which baseline clinical and radiological parameters predict development of CED in patients treated with intravenous thrombolysis. We used an image-based classification of CED with 3 degrees of severity (less severe CED 1 and most severe CED 3) on postintravenous thrombolysis imaging scans. We extracted data from 42 187 patients recorded in the SITS International Register (Safe Implementation of Treatments in Stroke) during 2002 to 2011. We did univariate comparisons of baseline data between patients with or without CED. We used backward logistic regression to select a set of predictors for each CED severity. CED was detected in 9579/42 187 patients (22.7%: 12.5% CED 1, 4.9% CED 2, 5.3% CED 3). In patients with CED versus no CED, the baseline National Institutes of Health Stroke Scale score was higher (17 versus 10; P<0.001), signs of acute infarct was more common (27.9% versus 19.2%; P<0.001), hyperdense artery sign was more common (37.6% versus 14.6%; P<0.001), and blood glucose was higher (6.8 versus 6.4 mmol/L; P<0.001). Baseline National Institutes of Health Stroke Scale, hyperdense artery sign, blood glucose, impaired consciousness, and signs of acute infarct on imaging were independent predictors for all edema types. The most important baseline predictors for early CED are National Institutes of Health Stroke Scale, hyperdense artery sign, higher blood glucose, decreased level of consciousness, and signs of infarct at baseline. The findings can be used to improve selection and monitoring of patients for drug or surgical treatment

Mechanical thrombectomy in acute ischemic stroke—experience from 6 years of practice

INTRODUCTION: We present our results from the first 6 years with mechanical thrombectomy in the treatment of ischemic stroke. METHODS: Every patient treated with mechanical thrombectomy for acute ischemic stroke from September 2005 to December 2011 was consecutively included in this retrospective analysis. Baseline and outcome data were retrieved from computerized records at the hospital. National Institute of Health Stroke Scale (NIHSS) score and the modified Rankin Scale (mRS) score were used as outcome parameters. Favorable outcome was defined as a mRS score of 0–2, corresponding to independence in activities of daily living. We also evaluated revascularization and severe adverse events, with focus on symptomatic intracranial hemorrhage. RESULTS: Good functional outcome (mRS 0–2) was achieved in 50 % (120/240) of all patients. For patients with no neurological deficit prior to stroke onset (i.e., mRS = 0 before stroke), the proportion with good functional outcome was 54 %. Symptomatic hemorrhages occurred in 4.6 % of the cases (5.7 % in the anterior circulation). CONCLUSION: In summary, our results supports that mechanical thrombectomy is a safe and effective method to restore blood flow in selected patients suffering from an acute ischemic stroke

Mitigating slipping-related mortality from purse seine fisheries for small pelagic fish: case studies from European Atlantic waters

The release of unwanted catches (UWC) from purse seines, while the catch is still in the water, is known as “slipping”. Once thought to be a benign process, compared to discarding UWC overboard from the fishing vessel, it is now recognised that “slipping” can lead to significant mortality in the released fish if done inappropriately. In this chapter, we examine purse seining and slipping operations, and discuss what drives slipping and potential mitigation measures to reduce slipping mortality. We use three examples of purse seine fisheries for small pelagic species in the North-east Atlantic; from Norway, Portugal and Spain. The ideal solution (identifying and avoiding UWC before the net is set) requires the development of tools to enable fishers to better characterise target schools in terms of key selection criteria, e.g., with respect to species, individual size and catch biomass. Such tools are being developed, based primarily on hydro-acoustic technology. However, some UWC in purse seine catches are inevitable, and operational improvements in slipping practices have been shown to significantly reduce stress and mortality in the released UWC. We conclude with a discussion on the challenges currently facing the implementation of the European Union (EU) Landing Obligation with regards to minimising slipping related mortality.info:eu-repo/semantics/publishedVersio

Teacher Identity Development Through Critical Self Reflection

Many educators struggle daily to balance the many facets of their teacher identity, encompassing their personal and professional lives, as well as how they are portrayed in the media and political realm. This along with the other demands of the job can often lead to teacher identity conflict. While teacher identity conflict is a necessary component to growth throughout one\u27s career, lack of support through these challenges can create frustration, stress, and ultimately cause educators to leave the field altogether. This paper explores the research question: How can educators engage in critical self reflection to overcome conflicts in their teacher identity? The literature suggests that while critical self reflection can be done alone, it is more powerful in a supportive environment of colleagues. Despite being a vital tool in overcoming teacher identity conflict, there is a lack of existing spaces for both pre-service and in-service educators to engage in critical self reflection with peers. Research suggests creating more opportunities for teachers to explore identity through critical self reflection in what are coined brave spaces: trusting, vulnerable communities educators committed to personal and professional growth. These brave spaces allow teachers to explore critical self reflection through conscious and intentional activities led by a facilitator that probes participants to think more deeply about systems of power and oppression. Implications for this paper include improving teacher access to brave spaces and continuing expanded research on critical self reflection and identity development for educators

Analysis of Cross Complementation of Archaeal Bax1 Protein in Saccharomyces cerevisiae

DNA repair mechanisms are essential in maintaining cell life and ensuring efficient cell replication. In this experiment, we tested for cross complementation of archaeal DNA repair genes (obtained from Methanosarcina acetivorans) in Saccharomyces cerevisiae yeast cells lacking Rad 1 and Rad 2 proteins. Five different cell conditions were tested: S. cerevisiae lacking rad 1 with a Bax 1 or a vector plasmid, S. cerevisiae lacking rad 2 with a Bax 1 or vector plasmid, and a wild type S. cerevisiae and no plasmid. Each week, cells were grown in broth culture, plated, and exposed to ultra-violent light, damaging the cell and inducing cellular DNA repair. After incubation, the plates were examined and cell counts were taken to determine percent survival after UV light exposure. Early results indicate that S. cerevisiae mutant strains carrying the Bax 1 gene can substitute for the Rad 1 protein but not the Rad 2 protein. We are currently conducting more trials of this experiment to increase confidence in our results and elaborate on current findings