The Total Synthesis of (–)-Scabrolide A

The first total synthesis of the norcembranoid diterpenoid scabrolide A is disclosed. The route begins with the synthesis of two chiral pool-derived fragments, which undergo a convergent coupling to expediently introduce all 19 carbon atoms of the natural product. An intramolecular Diels–Alder reaction and an enone–olefin cycloaddition/fragmentation sequence are then employed to construct the fused [5–6–7] linear carbocyclic core of the molecule and complete the total synthesis

Integrated multiple mediation analysis: A robustness–specificity trade-off in causal structure

Recent methodological developments in causal mediation analysis have addressed several issues regarding multiple mediators. However, these developed methods differ in their definitions of causal parameters, assumptions for identification, and interpretations of causal effects, making it unclear which method ought to be selected when investigating a given causal effect. Thus, in this study, we construct an integrated framework, which unifies all existing methodologies, as a standard for mediation analysis with multiple mediators. To clarify the relationship between existing methods, we propose four strategies for effect decomposition: two-way, partially forward, partially backward, and complete decompositions. This study reveals how the direct and indirect effects of each strategy are explicitly and correctly interpreted as path-specific effects under different causal mediation structures. In the integrated framework, we further verify the utility of the interventional analogues of direct and indirect effects, especially when natural direct and indirect effects cannot be identified or when cross-world exchangeability is invalid. Consequently, this study yields a robustness–specificity trade-off in the choice of strategies. Inverse probability weighting is considered for estimation. The four strategies are further applied to a simulation study for performance evaluation and for analyzing the Risk Evaluation of Viral Load Elevation and Associated Liver Disease/Cancer data set from Taiwan to investigate the causal effect of hepatitis C virus infection on mortality

A mediation approach to understanding socio-economic inequalities in maternal health-seeking behaviours in Egypt.

BACKGROUND: The levels and origins of socio-economic inequalities in health-seeking behaviours in Egypt are poorly understood. This paper assesses the levels of health-seeking behaviours related to maternal care (antenatal care [ANC] and facility delivery) and their accumulation during pregnancy and childbirth. Secondly, it explores the mechanisms underlying the association between socio-economic position (SEP) and maternal health-seeking behaviours. Thirdly, it examines the effectiveness of targeting of free public ANC and delivery care. METHODS: Data from the 2008 Demographic and Health Survey were used to capture two latent constructs of SEP: individual socio-cultural capital and household-level economic capital. These variables were entered into an adjusted mediation model, predicting twelve dimensions of maternal health-seeking; including any ANC, private ANC, first ANC visit in first trimester, regular ANC (four or more visits during pregnancy), facility delivery, and private delivery. ANC and delivery care costs were examined separately by provider type (public or private). RESULTS: While 74.2% of women with a birth in the 5-year recall period obtained any ANC and 72.4% delivered in a facility, only 48.8% obtained the complete maternal care package (timely and regular facility-based ANC as well as facility delivery) for their most recent live birth. Both socio-cultural capital and economic capital were independently positively associated with receiving any ANC and delivering in a facility. The strongest direct effect of socio-cultural capital was seen in models predicting private provider use of both ANC and delivery. Despite substantial proportions of women using public providers reporting receipt of free care (ANC: 38%, delivery: 24%), this free-of-charge public care was not effectively targeted to women with lowest economic resources. CONCLUSIONS: Socio-cultural capital is the primary mechanism leading to inequalities in maternal health-seeking in Egypt. Future studies should therefore examine the objective and perceived quality of care from different types of providers. Improvements in the targeting of free public care could help reduce the existing SEP-based inequalities in maternal care coverage in the short term

Inverse Odds Ratio-Weighted Estimation for Causal Mediation Analysis

An important scientific goal of studies in the health and social sciences is increasingly to determine to what extent the total effect of a point exposure is mediated by an intermediate variable on the causal pathway between the exposure and the outcome. A causal framework has recently been proposed for mediation analysis, which gives rise to new definitions, formal identification results and novel estimators of direct and indirect effects. In the present paper, the author describes a new inverse odds ratio-weighted (IORW) approach to estimate so-called natural direct and indirect effects. The approach which uses as a weight, the inverse of an estimate of the odds ratio function relating the exposure and the mediator is universal in that it can be used to decompose total effects in a number of regression models commonly used in practice. Specifically, the approach may be used for effect decomposition in generalized linear models with a nonlinear link function, and in a number of other commonly used models such as the Cox proportional hazards regression for a survival outcome. The approach is simple and can be implemented in standard software provided a weight can be specified for each observation. An additional advantage of the method is that it easily incorporates multiple mediators of a categorical, discrete or continuous nature

The Ursinus Weekly, March 19, 1945

Committee reveals full social calendar for spring semester • Amateur show will be Friday; civilians and Navy are eligible • Frosh to receive colors Thursday • Two weeks remain to originate May pageant for Circle prize • Ursinus representatives observe Cultural Olympic productions • Operetta leads are well-trained soloists • Vesper guest talks on future of Chinese race • Johnny the mailman is Ursinus\u27 favorite man • Open forum to discuss the church and peace • English Club elects 7 members; entire group to meet tonight • Red Cross drive nets $145.20 in one week campus campaign • College announces date for ASTRP test in April • Yearbook drive to end Saturday at midnight • Tribute to a regular fellow • Ursinus outswims Chestnut Hill, 36-21, in club\u27s first meet • Third team displays fast basketball in 25-19 win over St. John\u27s • Varsity coeds defeat Beaver, 23-21, in home game Saturday; Jayvee team clinches double-header with easy 28-19 victory • Dorm teams compete in basketball contests • Jayvee coeds lose one-point thriller • Chestnut Hill stops Ursinus varsity, 30-13https://digitalcommons.ursinus.edu/weekly/1701/thumbnail.jp

The Ursinus Weekly, June 10, 1946

Ninety-two students to receive degrees at seventy-sixth annual commencement: Dr. Johnson to deliver address; graduation week events listed • Group three to present two one-act plays at Curtain Club meeting • Student council to hold installation banquet on Tues. evening, June 18 • Athletes to hold banquet, Thursday • Juniors elect Paul Detwiler to presidency of 1947 class: K. Schroeder is junior prexy; frosh elect Hallinger leader; also names Eckenroth, Nikel, J. Rathgeb as other officers • Editors announce release date of next Lantern issue • Outstanding debaters honored by Tau Kappa Alpha fraternity • Dr. Armstrong is guest speaker of Brotherhood of St. Paul • Seven students chosen members of honorary dramatic society • YMCA president names seven men as new cabinet members • Men students elect J. Newlin to serve as YMCA president • Fishman heads pre-med group • Lois Williams to serve as head of International Relations Club • Dr. Campbell addresses Y interdenominational group • The Negro problem • New chef received culinary training as Merchant Marine • Delaware swamps baseball team 14-4; Hallinger leads bears with three hits • First deck wins title in intramural league; defeats third deck, 9-5 • Snell\u27s Belles trounce Penn coeds 18-0 as Erma Keyes delivers no-hit game • Penn Maids shut out Ursinus racqueteers, 5-0 • Ursinus coeds drop 5-0 match to Swarthmore • JV score 3-2 victory in match with U. of P. • Y holds semi-annual retreat to plan activities of coming year • Seniors will always remember certain things around campus • Journey to shore brings coeds adventure, relief from bookshttps://digitalcommons.ursinus.edu/weekly/1682/thumbnail.jp

The Ursinus Weekly, May 29, 1944

Girls elect Betty Dando, Anne Styer, Anne Baird to head organizations • Ken Keely to play for Navy ball Saturday; dinner and entertainment to precede dance • Local men ruined by secret weapon • Quay, Haines to be operetta comedy team in six-sided love tale • Penn provost to give graduation address • Christian faiths is Gross\u27 vespers topic • Ten members to be initiated into honorary debate society • Betty Tyson heads debaters; new members elected to club • Collegians to lead jam session featuring \u27Foul Five\u27 Wednesday • Dean of dentistry from Temple to address pre-med students • Juniors elect Francis Tisdale Ruby editor for coming year • Curtain Club holds elections; Elaine Loughin to be president • Fashion forecast is frightfully fantastic • Co-ed tennis team defeated, 3-2; Garnet ends Ursinus\u27 winning streak • Highland-Glenwood lead in softball • \u27Little Mid\u27, well-known in all major sports, is musician and artist • Ursinus upsets Villanova Wildcats 3-1, wins fifth straight game with Shegda • Girls\u27 interdorm softball has revised schedule • Jerry Batt reigns as stunning queen in unique pageant • Summer bus schedule to be adopted on June 4 • War bond to admit purchaser to Ringling Bros. circus June 8 • Fifty student to give blood at donor unit here Friday • Grad elected G.O.P. chairman • Professional callers lead folk dancing at Y party Fridayhttps://digitalcommons.ursinus.edu/weekly/1735/thumbnail.jp

Photoelectrochemical synthesis of DNA microarrays

Optical addressing of semiconductor electrodes represents a powerful technology that enables the independent and parallel control of a very large number of electrical phenomena at the solid-electrolyte interface. To date, it has been used in a wide range of applications including electrophoretic manipulation, biomolecule sensing, and stimulating networks of neurons. Here, we have adapted this approach for the parallel addressing of redox reactions, and report the construction of a DNA microarray synthesis platform based on semiconductor photoelectrochemistry (PEC). An amorphous silicon photoconductor is activated by an optical projection system to create virtual electrodes capable of electrochemically generating protons; these PEC-generated protons then cleave the acid-labile dimethoxytrityl protecting groups of DNA phosphoramidite synthesis reagents with the requisite spatial selectivity to generate DNA microarrays. Furthermore, a thin-film porous glass dramatically increases the amount of DNA synthesized per chip by over an order of magnitude versus uncoated glass. This platform demonstrates that PEC can be used toward combinatorial bio-polymer and small molecule synthesis.Defense Advanced Research Projects Agency (N66001-05-X6030)National Science Foundation (Grant CCR0122419

Friend or foe? The current epidemiologic evidence on selenium and human cancer risk.

Scientific opinion on the relationship between selenium and the risk of cancer has undergone radical change over the years, with selenium first viewed as a possible carcinogen in the 1940s then as a possible cancer preventive agent in the 1960s-2000s. More recently, randomized controlled trials have found no effect on cancer risk but suggest possible low-dose dermatologic and endocrine toxicity, and animal studies indicate both carcinogenic and cancer-preventive effects. A growing body of evidence from human and laboratory studies indicates dramatically different biological effects of the various inorganic and organic chemical forms of selenium, which may explain apparent inconsistencies across studies. These chemical form-specific effects also have important implications for exposure and health risk assessment. Overall, available epidemiologic evidence suggests no cancer preventive effect of increased selenium intake in healthy individuals and possible increased risk of other diseases and disorders