Statistical timing analysis via modern optimization lens

We formulate statistical static timing analysis (SSTA) as a mixed-integer program and as a geometric program, utilizing histogram approximations of the random variables involved. The geometric-programming approach scales linearly with the number of gates and quadratically with the number of bins in the histogram. This translates, for example, to solving the SSTA for a circuit of 400 gates with 30 bins per each histogram approximation of a random variable in 440 seconds.Comment: 23 pages, 7 figure

Sedimentary Iron Cycling and the Origin and Preservation of Magnetization in Platform Carbonate Muds, Andros Island, Bahamas

Carbonate muds deposited on continental shelves are abundant and well-preserved throughout the geologic record because shelf strata are difficult to subduct and peritidal carbonate units often form thick, rheologically strong units that resist penetrative deformation. Much of what we know about pre-Mesozoic ocean chemistry, carbon cycling, and global change is derived from isotope and trace element geochemistry of platform carbonates. Paleomagnetic data from the same sediments would be invaluable, placing records of paleolatitude, paleogeography, and perturbations to the geomagnetic field in the context and relative chronology of chemostratigraphy. To investigate the depositional and early diagenetic processes that contribute to magneitzation in carbonates, we surveyed over 500 core and surface samples of peritidal, often microbially bound carbonate muds spanning the last not, vert, similar 1000 yr and deposited on top of Pleistocene aeolianites in the Triple Goose Creek region of northwest Andros Island, Bahamas. Sedimentological, geochemical, magnetic and ferromagnetic resonance properties divide the sediment columns into three biogeochemical zones. In the upper sediments, the dominant magnetic mineral is magnetite, produced by magnetotactic bacteria and dissimiliatory microbial iron metabolism. At lower depths, above or near mean tide level, microbial iron reduction dissolves most of the magnetic particles in the sediment. In some cores, magnetic iron sulfides precipitate in a bottom zone of sulfate reduction, likely coupled to the oxidation of decaying mangrove roots. The remanent magnetization preserved in all oriented samples appears indistinguishable from the modern local geomagnetic field, which reflects the post-depositional origin of magnetic particles in the lower zone of the parasequence. While we cannot comment on the effects of late-stage diagenesis or metamorphism on remanence in carbonates, we postulate that early-cemented, thin-laminated parasequence tops in ancient peritidal carbonates are mostly likely to preserve syn-depositional paleomagnetic directions and magnetofossil stratigraphies

Does international work experience pay off? The relationship between international work experience, employability and career success: a 30-country, multi-industry study

Drawing on human capital theory, our study examines the relationship between international work experience and individuals' career success in terms of promotions and subjective financial success. We propose that these relationships are mediated by external employability and hypothesise a moderating role of national-level economic freedom. Using data from 19,421 respondents, residing in 30 countries and working in different occupational groups (managers, professionals, clerical and blue-collar workers), our results suggest that international work experience is positively related to promotions and subjective financial success across our study's different national contexts. These positive relationships were mediated by individuals' perceived external employability. Some support for the moderation of the relationship between international work experience and employability through economic freedom was only found when we differentiate between different types of international work experience. The findings enhance our understanding of the association between international work experience and career success from a human capital perspective

Careers in context: An international study of career goals as mesostructure between societies’ career-related human potential and proactive career behavior

Careers exist in a societal context that offers both constraints and opportunities for career actors. Whereas most studies focus on proximal individual and/or organisational‐level variables, we provide insights into how career goals and behaviours are understood and embedded in the more distal societal context. More specifically, we operationalise societal context using the career‐related human potential composite and aim to understand if and why career goals and behaviours vary between countries. Drawing on a model of career structuration and using multilevel mediation modelling, we draw on a survey of 17,986 employees from 27 countries, covering nine of GLOBE's 10 cultural clusters, and national statistical data to examine the relationship between societal context (macrostructure building the career‐opportunity structure) and actors' career goals (career mesostructure) and career behaviour (actions). We show that societal context in terms of societies' career‐related human potential composite is negatively associated with the importance given to financial achievements as a specific career mesostructure in a society that is positively related to individuals' proactive career behaviour. Our career mesostructure fully mediates the relationship between societal context and individuals' proactive career behaviour. In this way, we expand career theory's scope beyond occupation‐ and organisation‐related factors

A retrospective review of 911 calls to a regional poison control center

Background: There is little data as to what extent national Emergency Medical Services (EMS; 911) utilize poison control centers (PCCs). A review of data from our PCC was done to better understand this relationship and to identify potential improvements in patient care and health care savings. Methods: Retrospective chart review of a single PCC to identify calls originating from 911 sources over a 4-year study period (1/1/08-12/31/11). Recorded variables included the origin of call to the PCC, intent of exposure, symptoms, management site, hospital admission, and death. Odds ratios (OR) were developed using multiple logistic regressions to identify risk factors for EMS dispatch, management site, and the need for hospital admission. Results: A total of 7556 charts were identified; 4382 (58%) met inclusion criteria. Most calls (63.3%) involved accidental exposures and 31% were self-harm or misuse. A total of 2517 (57.4%) patients had symptoms and 2044 (50.8%) were transported to an Emergency Department (ED). Over 38% of calls (n = 1696) were handled primarily by the PCC and did not result in EMS dispatch; only 6.5% of cases (n = 287) with initial PCC involvement resulted in crew dispatch. There were 955 (21.8%) cases that resulted in admission, and five deaths. The OR for being transported to an ED was 45.4 (95% confidence interval [CI]: 30.2-68.4) when the crew was dispatched by the PCC. Hospital admission was predicted by intent for self-harm (OR 5.0; 95% CI: 4.1-6.2) and the presence of symptoms (OR 2.43; 95% CI: 1.9-3.0). The ORs for several other predictive variables are also reported. Conclusions: When 911 providers contact a PCC about poisoning-related emergencies, a history of intentional exposure and the presence of symptoms each predicted EMS dispatch by the PCC, patient transport to an ED, and hospital admission. Early involvement of a PCC may prevent the need for EMS activation or patient transfer to a health care facility

Does international work experience pay off? The relationship between international work experience, employability and career success: a 30-country, multi-industry study

Drawing on human capital theory, our study examines the relationship between international work experience and individuals' career success in terms of promotions and subjective financial success. We propose that these relationships are mediated by external employability and hypothesise a moderating role of national-level economic freedom. Using data from 19,421 respondents, residing in 30 countries and working in different occupational groups (managers, professionals, clerical and blue-collar workers), our results suggest that international work experience is positively related to promotions and subjective financial success across our study's different national contexts. These positive relationships were mediated by individuals' perceived external employability. Some support for the moderation of the relationship between international work experience and employability through economic freedom was only found when we differentiate between different types of international work experience. The findings enhance our understanding of the association between international work experience and career success from a human capital perspective

System-Wide Adaptations of Desulfovibrio alaskensis G20 to Phosphate-Limited Conditions.

The prevalence of lipids devoid of phosphorus suggests that the availability of phosphorus limits microbial growth and activity in many anoxic, stratified environments. To better understand the response of anaerobic bacteria to phosphate limitation and starvation, this study combines microscopic and lipid analyses with the measurements of fitness of pooled barcoded transposon mutants of the model sulfate reducing bacterium Desulfovibrio alaskensis G20. Phosphate-limited G20 has lower growth rates and replaces more than 90% of its membrane phospholipids by a mixture of monoglycosyl diacylglycerol (MGDG), glycuronic acid diacylglycerol (GADG) and ornithine lipids, lacks polyphosphate granules, and synthesizes other cellular inclusions. Analyses of pooled and individual mutants reveal the importance of the high-affinity phosphate transport system (the Pst system), PhoR, and glycolipid and ornithine lipid synthases during phosphate limitation. The phosphate-dependent synthesis of MGDG in G20 and the widespread occurrence of the MGDG/GADG synthase among sulfate reducing ∂-Proteobacteria implicate these microbes in the production of abundant MGDG in anaerobic environments where the concentrations of phosphate are lower than 10 μM. Numerous predicted changes in the composition of the cell envelope and systems involved in transport, maintenance of cytoplasmic redox potential, central metabolism and regulatory pathways also suggest an impact of phosphate limitation on the susceptibility of sulfate reducing bacteria to other anthropogenic or environmental stresses