Kinetics and mechanism of the reaction between atomic chlorine and dimethyl selenide; comparison with the reaction between atomic chlorine and dimethyl sulfide

Dimethyl selenide is the most abundant gaseous selenium species in marine environments. In this work, the value of the rate coefficient for the gas-phase reaction between dimethyl selenide and Cl atoms has been determined for the first time. The value of the second-order rate coefficient obtained was (5.0±1.4)×10–10 cm3 molecule–1 s–1. The very fast nature of the reaction means that, when estimating the lifetime of dimethyl selenide in the atmosphere, loss due to reaction with Cl atoms should be considered along with loss due to reaction with O3 and with OH and NO3 radicals. Analysis of the available kinetic data suggests that at 760 Torr the dominant reaction pathway for the reaction of Cl atoms with dimethyl selenide will be the addition of Cl to the Se atom forming an adduct of the type CH3Se(Cl)CH3. Theoretical calculations, at the B3LYP/6-311++G(2df,p)//B3LYP/6-311++G(d,p) level of theory, show that at 298 K the value of rH for the formation of the adduct is –111.4 kJ mol–1. This value may be compared to –97.0 kJ mol–1, the value calculated for rH for the formation of the analogous sulfur adduct, CH3S(Cl)CH3, following the reaction between Cl atoms and dimethyl sulfide. Variational RRKM theory was used to predict the thermal decomposition rates of the two adducts back to starting materials. The estimated rate constant for the decomposition of the selenium adduct to the reactants is 5×10–5 s–1, compared to 0.02 s–1 in the case of the sulfur adduct. However, our calculations suggest that the CH3Se(Cl)CH3 adduct, which is initially formed highly excited, will not be stabilised under atmospheric conditions, but rather will decompose to yield CH3SeCl and CH3, a process that is calculated to be exothermic with respect to the initial reactants by 5.8 kJ mol–1. The formation of CH3SCl and CH3 from the sulfur adduct, on the other hand, is endothermic by 20.8 kJ mol–1 with respect to the initial reactants, and is thus not expected to occur

DISCONNECTED FROM THE FRONT LINES: LACK OF WARFIGHTER EXPERIENCE IN ACQUISITIONS YIELDS UNACCEPTABLE END STATES

Over the past few decades, the Defense Acquisition System (DAS) has been under constant fire by Congress, taxpayers, and warfighters for unacceptable cost, schedule, and performance outcomes. This plague has been well documented, discussed, and many potential corrective measures implemented over the years with futile results. This leaves the warfighter with delivered capabilities not meeting actual operational needs, routinely late to field, yielding them irrelevant, and coming with unrecoverable cost overruns. One significant area of the acquisition process, the focus of this research, has the most impact on a program’s outcome yet had the least amount of change: who represents the warfighter during requirements generation and management throughout the life cycle. A program’s requirements establish the end cost, schedule, and performance thresholds that, once a program matures, are extremely difficult to change without a sizable penalty. This research documents a correlation between troubled programs and poor requirements support due to an operational knowledge gap caused by a lack of proficient end-user warfighter representatives involved and empowered in the process. Related, due to the inherent differences in views, experience, and expectations between a career acquisition professional and a warfighter, data shows a need for a blended professional within the DAS. The research shows failure to bridge this personnel gap will predictably yield the same unacceptable results.Lieutenant Commander, United States NavyCommander, United States NavyChief Warrant Officer Three, United States NavyApproved for public release. Distribution is unlimited

Work-life Events Theory: Making Sense of Shock Events in Dual-Earner Couples

Dual-earner couples are increasingly prevalent and encounter demands arising from each partner’s commitment to various work and life domains. Unfortunately, there has been little theoretical progress in explaining how dual-earner couples navigate work-life shock events, which we define as disruptive, novel, and critical events that require investment of a couple’s resources. Drawing from identity and sensemaking theories, we develop a theory of work-life shock events to explain how dual-earner couples perceive and respond to these events. We theorize that partners initially make sense of the event as individuals and then engage in couple-level sensemaking. We argue that each individual’s shock intensity perceptions are shaped by the shock event’s characteristics and the identity factors of role salience hierarchy and future self. A subsequent couple-level process of sensemaking ensues, influenced by the salience of the originating domain and partner role, as well as relational identity factors. Couple-level shock intensity perceptions result in the couple’s decision regarding resource investment in the shock event’s originating domain. We discuss implications for future research and for organizations

Is U.S. CEO Compensation Inefficient Pay Without Performance?

In Pay Without Performance, Professors Lucian Bebchuk and Jesse Fried develop and summarize the leading critiques of current executive compensation practices in the United States. This book, and their highly influential earlier article, Managerial Power and Rent Extraction in the Design of Executive Compensation, with David Walker offer a negative, if mainstream, assessment of the state of U.S. executive compensation: U.S. executive compensation practices are failing in a widespread manner, and much systemic reform is needed. The purpose of our Review is to summarize the book and to offer some counterarguments to try to balance what is becoming an increasingly one-sided debate. The book\u27s thesis is that executive compensation practices in the U.S. benefit corporate executives at the expense of shareholders through implicit and explicit corruption of the pay-setting process. It argues that CEO employment contracts are bad for shareholders (not optimal ) because they are the product of managerial power. Managerial power arises, the authors claim, because boards of directors at public companies are beholden to the firm\u27s top executives, largely due to management\u27s control over the director nomination process. Weak compensation committees thus do little to protect the firm in its pay negotiations with the CEO, leading to levels of executive pay that are both inappropriately high and have inappropriately low levels of incentives. The only constraint on this process is outrage, either among the firm\u27s shareholders or the general public. This outrage constraint, however, only polices extreme cases of executive overcompensation

Prevalence of Liver Cirrhosis and Its Association With Obesity Among Mexican Americans: An Evidence Synthesis

Introduction: Chronic liver disease is the 6th and 7th leading cause of death in Hispanic men and Hispanics, respectively.1 In contrast to other causes of liver disease, the prevalence of nonalcoholic liver disease has been growing as is diabetes and obesity.2 Objective: There is a paucity of data regarding the prevalence of cirrhosis for Mexican Americans in South Texas. The aim of this evidence synthesis is to investigate the prevalence of cirrhosis in Hispanic populations and its relationship with obesity. Methods: PubMed was used to perform a thorough literature search on September10, 2020. The terms “liver cirrhosis” and “obesity” were combined with the subheading\u27s “epidemiology,” “genetics,” and “complications.” Five remained after applying criteria. Results: In a cohort of Hispanic patients in South Texas, the prevalence of cirrhosis/fibrosis was estimated to be 3.54%, and central obesity was an independent risk factor for cirrhosis/advanced fibrosis (p=0.04).3 Moderate to severe fibrosis has a statistically significant higher average BMI compared to those with none to mild fibrosis (p\u3c0.001).4 A study in multiple Mexican regions found increased mortality from cirrhosis with statistically significant findings in the South and North regions (p\u3c0.0001).5 Obesity only increased in the Central and Mexico City regions.5 Discussion: Obesity was an independent risk factor for cirrhosis and 65.3% of cirrhosis and advanced fibrosis cases may be attributable to obesity alone in a cohort of Hispanic patients.3Since South Texas has one of the highest rates of obesity in the US, this population is susceptible to high rates of liver disease, obesity and mortality. Conclusions: Hispanic patients that are obese have an increased risk of liver disease and associated mortality.3–6These study findings are limited by the paucity of relevant research and variable methodology of the studies. Further research is needed to evaluate the impact of obesity on liver disease for this population

Managing the gilt pool

1 online resource (PDF, 2 pages)This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

KIC 3749404: a heartbeat star with rapid apsidal advance indicative of a tertiary component

Heartbeat stars are eccentric (e> 0.2) ellipsoidal variables whose light curves resemble a cardiogram. We present the observations and corresponding model of KIC 3749404, a highly eccentric (e = 0.66), short period (P = 20.3 d) heartbeat star with tidally induced pulsations. A binary star model was created using phoebe, which we modified to include tidally induced pulsations and Doppler boosting. The morphology of the photometric periastron variation (heartbeat) depends strongly on the eccentricity, inclination and argument of periastron. We show that the inclusion of tidally induced pulsations in the model significantly changes the parameter values, specifically the inclination and those parameters dependent on it. Furthermore, we determine the rate of apsidal advance by modelling the periastron variation at the beginning and end of the 4-yr Kepler data set and dividing by the elapsed time. We compare the model with the theoretical expectations for classical and general relativistic apsidal motion and find the observed rate to be two orders of magnitude greater than the theoretical rate. We find that the observed rate cannot be explained by tidally induced pulsations alone and consequently hypothesise the presence of a third body in the system

Ion dynamics in perturbed quadrupole ion traps

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