Need a Lift? An Elevator Queueing Problem

Various aspects of the behavior and dispatching of elevators (lifts) were studied. Monte Carlo simulation was used to study the statistics of the several models for the peak demand at uppeak times. Analytical models problems were used to prove or disprove whether schemes were optimal. A mostly integer programming problem was formulated but not studied further

MAC OS X Forensics: Password Discovery

OS X provides a password-rich environment in which passwords protect OS X resources and perhaps many other resources accessed through OS X. Every password an investigator discovers in an OS X environment has the potential for use in discovering other such passwords, and any discovered passwords may also be useful in other aspects of an investigation, not directly related to the OS X environment. This research advises the use of multiple attack vectors in approaching the password problem in an OS X system, including the more generally applicable non-OS X-specific techniques such as social engineering or well-known password cracking techniques such as John the Ripper or other versions of dictionary attacks and Rainbow table attacks. In some successful approaches the components of the attack vector will use more OS X specific techniques such as those described here: application-provided password revealing functions, a Javascript attack, an “Evil Website” attack, system file scavenging, exploitation of the keychain, and an OS X install disk attack. Keywords: OS X, password, password discovery, social engineering, sleepimage, keychai

A life course approach to the relationship between fetal growth and hypothalamic-pituitary-adrenal axis function

CONTEXT: Human and animal studies suggest that hypothalamic-pituitary-adrenal axis (HPA-A) function may be programmed in utero; however, these findings are inconsistent. Given the powerful metabolic actions of cortisol, it is important to clarify the influence of early life on adult HPA-A function. OBJECTIVE: To determine the relationship between fetal growth and HPA-A stress response to a psychosocial stressor in young adults. DESIGN: Multigenerational, prospective cohort study (the Raine Study) conducted between 1989 and 1991. SETTING: King Edward Memorial Hospital, Perth, Western Australia, Australia. PARTICIPANTS: A total of 917 participants aged 18 years from Gen2 of the Raine Study. MAIN OUTCOME MEASURES: Measures of hypothalamic-pituitary-adrenal axis function before and after exposure to the Trier Social Stress Test. RESULTS: In fully adjusted models, an inverse linear relationship was observed between birthweight and plasma measures of (1) baseline cortisol (β = -0.90%, 95% CI: -1.73 to -0.07; P = 0.03); (2) peak cortisol (β = -0.78%, 95% CI -1.51 to -0.06; P = 0.03); (3) area under the curve with respect to ground (β = -0.89%, 95% CI -1.60 to -0.18; P = 0.01); and (4) adrenal sensitivity (β = -1.02, 95% CI: -1.85 to -0.18; P = 0.02). Similar results were demonstrated for percent optimal birthweight. No consistent quadratic relationships were identified. No associations were found between measures of fetal adiposity and HPA-A function at age 18 years, or fetal growth and HPA-A response pattern. Removal of anticipatory responders from the models substantially attenuated the observed relationships. CONCLUSION: We observed an inverse linear relationship between fetal growth and HPA-A function at age 18 years. This differs from the inverse parabolic relationship (inverted U curve) reported in adults of advanced age. Altered adrenal sensitivity may underlie this relationship

Tracking of vitamin D status from childhood to early adulthood and its association with peak bone mass

Background: To our knowledge, there are few longitudinal studies of vitamin D status from childhood to early adulthood, and it is uncertain whether vitamin D predicts peak bone mass in young adults. Objectives: The purpose of this longitudinal study was to evaluate the long-term stability of vitamin D status from ages 6 to 20 y in healthy individuals and to study associations between serum 25-hydroxyvitamin D [25(OH)D] at different developmental stages and bone mass measured at age 20 y. Design: Participants were offspring of the Western Australian Pregnancy Cohort (Raine) study. Serum 25(OH)D was assessed at ages 6, 14, 17, and 20 y, and whole-body bone mineral content (BMC) and bone mineral density (BMD) were measured at age 20 y through the use of dual-energy X-ray absorptiometry (DXA). Our analysis included 821 participants (385 females) who had ≥3 serum 25(OH)D measures and DXA data. We used latent class growth analysis and identified 4 vitamin D status trajectories: consistently lower (n = 259), decreasing (n = 125), increasing (n = 138), and consistently higher (n = 299). Results: There were significant correlations between serum 25(OH)D concentrations at different time points in both sexes (r = 0.346–0.560, P \u3c 0.001), with stronger correlations at adjacent time points. In males, but not in females, serum 25(OH)D at ages 6, 17, and 20 y was positively associated with total-body BMC and BMD at age 20 y [covariate-adjusted increments of 40.7–53.9 g and 14.7–18.6 mg/cm2, respectively, per 25 nmol/L 25(OH)D]; when 25(OH)D at all 4 ages was included in the same model, the concentration at age 6 y remained significant. Males in the “consistently higher” trajectory had 3.2–3.4% higher total body BMC and BMD than those who were in the “consistently lower” trajectory, accounting for age and anthropometric and lifestyle factors. Conclusions: Within both sexes, there are moderate associations between vitamin D status measured in prepuberty, adolescence, and early adulthood. Vitamin D status in childhood is a significant predictor of peak bone mass in male but not female subjects

Dual energy X-ray absorptiometry compared with anthropometry in relation to cardio-metabolic risk factors in a young adult population: Is the ‘Gold Standard’ tarnished?

Background and Aims: Assessment of adiposity using dual energy x-ray absorptiometry (DXA) has been considered more advantageous in comparison to anthropometryfor predicting cardio-metabolic risk in the older population, by virtue of its ability to distinguish total and regional fat. Nonetheless, there is increasing uncertainty regarding the relative superiority of DXA and little comparative data exist in young adults. This study aimed to identify which measure of adiposity determined by either DXA or anthropometry is optimal within a range of cardio-metabolic risk factors in young adults. Methods and Results: 1138 adults aged 20 years were assessed by DXA and standard anthropometry from the Western Australian Pregnancy Cohort (Raine) Study. Cross-sectional linear regression analyses were performed. Waist to height ratio was superior to any DXA measure with HDL-C. BMI was the superior model in relation to blood pressure than any DXA measure. Midriff fat mass (DXA) and waist circumference were comparable in relation to glucose. For all the other cardio-metabolic variables, anthropometricand DXA measures were comparable. DXA midriff fat mass compared with BMI or waist hip ratio was the superior measure for triglycerides, insulin and HOMA-IR. Conclusion: Although midriff fat mass (measured by DXA) was the superior measure with insulin sensitivity and triglycerides, the anthropometricmeasures were better or equal with various DXA measures for majority of the cardio-metabolic risk factors. Our findings suggest, clinical anthropometry is generally as useful as DXA in the evaluation of the individual cardio-metabolic risk factors in young adults

Development of B-1 cells: segregation of phosphatidyl choline-specific B cells to the B-1 population occurs after immunoglobulin gene expression

Adult mice have two easily recognizable subsets of B cells: the predominant resting population of the spleen, called B-2, and those called B-1, which predominate in coelomic cavities and can express CD5. Some antibody specificities appear to be unique to the B-1 population. Cells expressing antibody specific for phosphatidyl choline (PtC) are the most frequent, comprising 2-10% of peritoneal B cells in normal mice. To understand the basis for the segregation of the anti-PtC specificity to this population, we have produced transgenic (Tg) mice expressing the rearranged VH12 and V kappa 4 genes of a PtC-specific B- 1 cell lymphoma. We find that VH12-Tg and VH12/V kappa 4 double-Tg mice develop very high numbers of PtC-specific peritoneal and splenic B cells. These cells have the characteristics of B-1 cells; most are CD5+, and are all IgMhi, B220lo, and CD23-. In the peritoneum these cells are also CD11b+. In addition, adult mice have many splenic B cells (up to one third of Tg+ cells) that express the VH12 Tg but do not bind PtC, presumably because they express a V kappa gene other than V kappa 4. These cells appear to be B-2 cells; they are CD23+, CD11b-, IgMlo, B220hi, and CD5-. Thus, mice given either the VH12 Tg alone or together with the V kappa 4 Tg develop a large population of PtC- specific B cells which belong exclusively to the B-1 population. Since B-2 cells can express the VH12 and V kappa 4 gene separately, we interpret these data to indicate that the events leading to the segregation of PtC-specific B cells to the B-1 population in normal mice are initiated after Ig gene rearrangement and expression. These data are discussed with regard to hypotheses of the origin of B-1 cells. We also find that VH12-Tg mice have a marked decrease in the generation of Tg-expressing B cells in adult bone marrow, but not newborn liver. We speculate that this may be related to positive selection of VH12-expressing B cells during differentiation

FAN1 activity on asymmetric repair intermediates is mediated by an atypical monomeric virus-type replication-repair nuclease domain

FAN1 is a structure-selective DNA repair nuclease with 5' flap endonuclease activity, involved in the repair of interstrand DNA crosslinks. It is the only eukaryotic protein with a virus-type replication-repair nuclease ("VRR-Nuc") "module" that commonly occurs as a standalone domain in many bacteria and viruses. Crystal structures of three representatives show that they structurally resemble Holliday junction resolvases (HJRs), are dimeric in solution, and are able to cleave symmetric four-way junctions. In contrast, FAN1 orthologs are monomeric and cleave 5' flap structures in vitro, but not Holliday junctions. Modeling of the VRR-Nuc domain of FAN1 reveals that it has an insertion, which packs against the dimerization interface observed in the structures of the viral/bacterial VRR-Nuc proteins. We propose that these additional structural elements in FAN1 prevent dimerization and bias specificity toward flap structures

Prenatal stress and risk of behavioral morbidity from age 2 to 14 years: The influence of the number, type, and timing of stressful life events

The maternal experience of stressful events during pregnancy has been associated with a number of adverse consequences for behavioral development in offspring, but the measurement and interpretation of prenatal stress varies among reported studies. The Raine Study recruited 2900 pregnancies and recorded life stress events experienced by 18 and 34 weeks’ gestation along with numerous sociodemographic data. The mother’s exposure to life stress events was further documented when the children were followed-up in conjunction with behavioral assessments at ages 2, 5, 8, 10, and 14 years using the Child Behavior Checklist. The maternal experience of multiple stressful events during pregnancy was associated with subsequent behavioral problems for offspring. Independent (e.g., death of a relative, job loss) and dependent stress events (e.g., financial problems, marital problems) were both significantly associated with a greater incidence of mental health morbidity between age 2 and 14 years. Exposure to stressful events in the first 18 weeks of pregnancy showed similar associations with subsequent total and externalizing morbidity to events reported at 34 weeks of gestation. These results were independent of postnatal stress exposure. Improved support for women with chronic stress exposure during pregnancy may improve the mental health of their offspring in later life