21 research outputs found
Predicting mergers and acquisitions
Being able to predict a merger or acquisition before it takes place could lead to an investor earning a premium, if they owned shares of the targeted firm before the merger or acquisition attempt is announced. On average acquiring firms pay a premium when acquiring or merging with a targeted firm. This study uses publicly available financial information for 7,267 attempted takeover targets and 52,343 non-targeted firms for the period January 3, 2000 through December 31, 2007 to estimate (using logit) predictive models. Financial ratios are constructed based on six hypotheses found in the literature. Although statistical evidence supports a few of the hypotheses, the low predictive power of the models does not indicate the ability to accurately predict targeted firms ahead of time, let alone with any economic significance
Fine-scale Genetic Structure and Social Organization in Female White-tailed Deer
Social behavior of white-tailed deer (Odocoileus virginianus) can have important management implications.
The formation of matrilineal social groups among female deer has been documented and management strategies have been proposed based on this well-developed social structure. Using radiocollared (n = 17) and hunter or vehicle- killed (n = 21) does, we examined spatial and genetic structure in white-tailed deer on a 7,000-ha portion of the
Savannah River Site in the upper Coastal Plain of South Carolina, USA. We used 14 microsatellite DNA loci to calculate pairwise relatedness among individual deer and to assign doe pairs to putative relationship categories. Linear distance and genetic relatedness were weakly correlated (r = â0.08, P = 0.058). Relationship categories differed in mean spatial distance, but only 60% of first-degree-related doe pairs (full sibling or motherâoffspring pairs) and
38% of second-degree-related doe pairs (half sibling, grandmotherâgranddaughter pairs) were members of the same social group based on spatial association. Heavy hunting pressure in this population has created a young age structure among does, where the average age is4.5 years old. Thisâcombined with potentially elevated dispersal among young doesâcould limit the formation of persistent, cohesive social groups. Our results question the universal applicability of recently proposed models of spatial and genetic structuring in white-tailed deer, particularly in areas with differing harvest histories
The StO2 non-invasive tissue hypoperfusion monitor as a screening tool for early sepsis detection in the emergency department
Background: Early Recognition of patients with sepsis induced tissue hypoperfusion (SITH) Remains a significant clinical challenge. Non--âinvasive Tissue oxygenation saturation (StO2) Monitors have been developed to provide rapid, low--âcost, and non--âinvasive bedside assessments of tissue oxygen extraction; they have not been well validated as an initial screening tool for sepsis in the ED. Objectives: To Assess the efficacy of initial bedside StO2 Readings in the early identification of patients with SITH And to compare StO2 Readings with lactate levels. Methods: IRB approved, prospective, observational pilot study of a convenience sample of ED Patients presenting with a sepsis continuum diagnosis. Setting: Urban Tertiary care center with 90k visits/yr. Inclusion criteria: Suspicion Of new infection plus 2 SIRS criteria. Exclusion criteria: \u3c18 Or no suspicion of infection. Study procedures: Demographics, co--âmorbidities, clinical data, treatment, disposition, and mortality were collected. A Portable In--âSpectra âSpot Checkâ StO2 Monitor was used totake a StO2 Reading at the thenar eminence; a second reading was taken three hours later. All Investigators were trained with the device to record data with a high degree of accuracy and reliability. Abnormal StO2 Was defined as \u3c80% or\u3e91%. The Study was observational and there were no clinical interventions. Descriptive Statistics were employed and Sensitivity/Specificity, Likelihood ratios, andNPV/PPV Were calculated with 95% Confidence intervals (in parenthesis) where appropriate. Results: 79 Patients were enrolled into the study. Mean Age 63 (range 21--â96). 61 Were admitted to the hospital, 5 To ICU (100% With St02\u3c74%). 3 Mortalities (100% With St02\u3c72%). 75% (9/12) Of patients with an ED Lactate \u3e2.3 Had an abnormal St02. 80% (4/5) For lactate \u3e3, And 100%(3/3) For Lactate \u3e4. For Any initial SITH (MAP\u3c65 Or Lactate \u3e2.3): Sensitivity: 92% (77.5--â98.2), Specificity: 82.2% (67.9--â92), +LR: 5.2 (2.7--â9.7), --âLR: 0.1 (0.03--â0.3), PPV: 80.5% (65.1--â91.2), NPV: 92.5% (80--â98.3). Conclusions: StO2 May be a useful, rapid, low--âcost, and non--âinvasive bedside screening tool for SITH In the ED, Particularly for severely ill patients. Further Studies are needed to determine StO2âs Ability to predict mortality and assess response to therapy
Design of Lightweight Fills for Road Embankments on Boston\u27s Central Artery/Tunnel Project
The use of lightweight-fill materials for highway construction increased significantly worldwide during the 1990s. Predominant with this trend was the increased use of cellular geosynthetics (geofoams and geocombs), especially block-molded expanded polystyrene (EPS) geofoam, on highway and bridge embankments. EPS geofoam is increasingly recognized as an important tool for reducing overall cost of highways through accelerated construction . Thus, it was appropriate that lightweight-fill materials, mostly EPS, were the materials of choice on Bostonâs Central Artery/Tunnel (CA/T) Project, commonly known as the Big Dig . EPS highway embankments have been constructed, as part of a cost-and schedule-initiative, replacing the original design concepts for eight transition highway structures on a recent CA/T construction contract. The use of EPS-block geofoam on the CA/T included the first-time implementation of newly developed NCHRP research and AASHTO based design guidelines, material/product specifications as well as formulating innovative solutions to several technical challenges. These challenges centered on relatively tall and slender EPS fills placed over soft soils subjected to periodic flooding and seismic loading within a crowded urban environment. This paper presents a detailed outline of the design process together with the impacts of the buoyancy conditions and seismic loading on the design of EPS highway embankments. Also included is a discussion of other lightweight-fill materials such as geocombs (considered but not used) and expanded-shale aggregate (used in limited quantities)
Youth Single-Sport Specialization in Professional Baseball Players.
Background: An increasing number of youth baseball athletes are specializing in playing baseball at younger ages.
Purpose: The purpose of our study was to describe the age and prevalence of single-sport specialization in a cohort of current professional baseball athletes. In addition, we sought to understand the trends surrounding single-sport specialization in professional baseball players raised within and outside the United States (US).
Study Design: Cross-sectional study; Level of evidence, 3.
Methods: A survey was distributed to male professional baseball athletes via individual team athletic trainers. Athletes were asked if and at what age they had chosen to specialize in playing baseball at the exclusion of other sports, and data were then collected pertaining to this decision. We analyzed the rate and age of specialization, the reasons for specialization, and the athlete\u27s perception of injuries related to specialization.
Results: A total of 1673 professional baseball athletes completed the survey, representing 26 of the 30 Major League Baseball (MLB) organizations. Less than half (44.5%) of professional athletes specialized in playing a single sport during their childhood/adolescence. Those who reported specializing in their youth did so at a mean age of 14.09 ± 2.79 years. MLB players who grew up outside the US specialized at a significantly earlier age than MLB players native to the US (12.30 ± 3.07 vs 14.89 ± 2.24 years, respectively;
Conclusion: This study challenges the current trends toward early youth sport specialization, finding that the majority of professional baseball athletes studied did not specialize as youth and that those who did specialize did so at a mean age of 14 years. With the potential cumulative effects of pitching and overhead throwing on an athlete\u27s arm, the trend identified in this study toward earlier specialization within baseball is concerning
APOE4 allele disrupts resting state fMRI connectivity in the absence of amyloid plaques or decreased CSF AÎČ42
Identifying high risk populations is an important component of disease prevention strategies. One approach is examining neuroimaging parameters that differ in Alzheimerâs disease (AD), including functional connections known to be disrupted within the âdefault mode networkâ (DMN). We have previously shown these same disruptions in cognitively normal elderly, who have amyloid-beta (AÎČ) plaques detected using PIB PET imaging, suggesting neuronal toxicity of plaques. Here we sought to determine if pathological effects of apolipoprotein E Δ4 (APOE4) genotype could be seen independent of AÎČ plaque toxicity by examining resting state fMRI functional connectivity (fcMRI ) in participants without preclinical fibrillar amyloid deposition (PIBâ). Cognitively normal participants enrolled in longitudinal studies (n = 100, mean age = 62) who were PIBâ were categorized into those with and without an APOE 4 allele and studied using fcMRI. APOE 4 allele carriers (E4+) differed significantly from E4â in functional connectivity of the precuneus to several regions previously defined as having abnormal connectivity in a group of AD participants. These effects were observed prior to any manifestations of cognitive changes and in the absence of brain fibrillar amyloid-beta (AÎČ) plaque deposition, suggesting that early manifestations of a genetic effect can be detected using fcMRI and that these changes may antedate the pathological effects of fibrillar amyloid plaque toxicity
Quantitative analysis of PiB-PET with FreeSurfer ROIs
In vivo quantification of ÎČ-amyloid deposition using positron emission tomography is emerging as an important procedure for the early diagnosis of the Alzheimer's disease and is likely to play an important role in upcoming clinical trials of disease modifying agents. However, many groups use manually defined regions, which are non-standard across imaging centers. Analyses often are limited to a handful of regions because of the labor-intensive nature of manual region drawing. In this study, we developed an automatic image quantification protocol based on FreeSurfer, an automated whole brain segmentation tool, for quantitative analysis of amyloid images. Standard manual tracing and FreeSurfer-based analyses were performed in 77 participants including 67 cognitively normal individuals and 10 individuals with early Alzheimer's disease. The manual and FreeSurfer approaches yielded nearly identical estimates of amyloid burden (intraclass correlation = 0.98) as assessed by the mean cortical binding potential. An MRI test-retest study demonstrated excellent reliability of FreeSurfer based regional amyloid burden measurements. The FreeSurfer-based analysis also revealed that the majority of cerebral cortical regions accumulate amyloid in parallel, with slope of accumulation being the primary difference between regions
Alignment of the CMS silicon tracker during commissioning with cosmic rays
The CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3-4 microns RMS in the barrel and 3-14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance