1-octadecene monolayers on Si(111) hydrogen-terminated surfaces: effects of substrate doping

We have studied the electronic properties, in relation to their structural properties, of monolayers of 1-octadecene attached on a hydrogen-terminated (111) silicon surface. The molecules are attached using the free-radical reaction between C=C and Si-H activated by an ultraviolet illumination. We have compared the structural and electrical properties of monolayers formed on silicon substrate of different types (n-type and p-type) and different doping concentrations from low-doped (~1E14 cm-3) to highly doped (~1E19 cm-3) silicon substrates. We show that the monolayers on n-, p- and p+ silicon are densely packed and that they act as very good insulating films at a nanometer thickness with leakage currents as low as ~1E-7 A.cm-2 and high quality capacitance-voltage characteristics. The monolayers formed on n+-type silicon are more disordered and therefore exhibit larger leakage current densities (>1E-4 A.cm-2) when embedded in a silicon/monolayer/metal junction. The inferior structural and electronic properties obtained with n+-type silicon pinpoint the important role of surface potential and of the position of the surface Fermi level during the chemisorption of the organic monolayers.Comment: 33 pages, 8 figures, to be published J. Appl. Phy

Exempting Air Quality Permits May Just Help Reduce Greenhouse Gas Emissions: SF 1567 and Anaerobic Manure Digestion in Minnesota

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Comprehensive Monosynaptic Rabies Virus Mapping of Host Connectivity with Neural Progenitor Grafts after Spinal Cord Injury.

Neural progenitor cells grafted to sites of spinal cord injury have supported electrophysiological and functional recovery in several studies. Mechanisms associated with graft-related improvements in outcome appear dependent on functional synaptic integration of graft and host systems, although the extent and diversity of synaptic integration of grafts with hosts are unknown. Using transgenic mouse spinal neural progenitor cell grafts expressing the TVA and G-protein components of the modified rabies virus system, we initiated monosynaptic tracing strictly from graft neurons placed in sites of cervical spinal cord injury. We find that graft neurons receive synaptic inputs from virtually every known host system that normally innervates the spinal cord, including numerous cortical, brainstem, spinal cord, and dorsal root ganglia inputs. Thus, implanted neural progenitor cells receive an extensive range of host neural inputs to the injury site, potentially enabling functional restoration across multiple systems

Psychometric Evaluation of an Instrument to Measure Prospective Pregnancy Preferences: The Desire to Avoid Pregnancy Scale.

BACKGROUND:Existing approaches to measuring women's pregnancy intentions suffer important limitations, including retrospective assessment, overly simple categories, and a presumption that all women plan pregnancies. No psychometrically valid scales exist to prospectively measure the ranges of women's pregnancy preferences. MATERIALS AND METHODS:Using a rigorous construct modeling approach, we developed a scale to measure desire to avoid pregnancy. We developed 60 draft items from existing research, assessed comprehension through 25 cognitive interviews, and administered items in surveys with 594 nonpregnant women in 7 primary and reproductive health care facilities in Arizona, New Jersey, New Mexico, South Carolina, and Texas in 2016-2017. We used item response theory to reduce the item set and assess the scale's reliability, internal structure validity, and external validity. Items were included based on fit to a random effects multinomial logistic regression model (partial credit item response model), correspondence of item difficulty with participants' pregnancy preference levels, and consistency of each item's response options with overall scale scores. RESULTS:The 14 final items covered 3 conceptual domains: cognitive preferences, affective feelings, and practical consequences. Items fit the unidimensional model, with a separation reliability of 0.90 (Cronbach α: 0.95). The scale met established criteria for internal validity, including correspondence between each item's response categories and overall scale scores. We found no important differential item functioning by participant characteristics. CONCLUSIONS:A robust measure is available to prospectively measure desire to avoid pregnancy. The measure can aid in identifying women who could benefit from contraceptive care and research on less desired pregnancy

Perceived stress and emotional social support among women who are denied or receive abortions in the United States: a prospective cohort study.

BackgroundExamining women's stress and social support following denial and receipt of abortion furthers understanding of the effects of unwanted childbearing and abortion on women's well-being. This study investigated perceived stress and emotional social support over time among women who were denied wanted abortions and who received abortions, and compared outcomes between the groups.MethodsThe Turnaway Study is a prospective cohort study of women who sought abortions at 30 abortion facilities across the United States, and follows women via semiannual phone interviews for five years. Participants include 956 English or Spanish speaking women aged 15 and over who sought abortions between 2008 and 2010 and whose gestation in pregnancy fit one of three groups: women who presented up to three weeks beyond a facility's gestational age limit and were denied an abortion; women presenting within two weeks below the limit who received an abortion; and women who received a first trimester abortion. The outcomes were modified versions of the Perceived Stress Scale and the Multidimensional Scale of Perceived Social Support. Longitudinal mixed effects models were used to assess differences in outcomes between study groups over 30 months.ResultsWomen denied abortions initially had higher perceived stress than women receiving abortions near gestational age limits (1.0 unit difference on 0-16 scale, P = 0.003). Women receiving first-trimester abortions initially had lower perceived stress than women receiving abortions near gestational age limits (0.6 difference, P = 0.045). By six months, all groups' levels of perceived stress were similar, and levels remained similar through 30 months. Emotional social support scores did not differ among women receiving abortions near gestational limits versus women denied abortions or women having first trimester abortions initially or over time.ConclusionsSoon after being denied abortions, women experienced higher perceived stress than women who received abortions. The study found no longer-term differences in perceived stress or emotional social support between women who received versus were denied abortions

The Exploration by Means of Repertory Grids of Semantic Differences Among Names for Office Documents.

We used repertory grids to investigate the differences in names assigned to a selected list of 11 frequently mentioned office documents. The assumption is that naming reflects a classificatory decision and is based on a complex set of perceived aspects (which we call constructs) of the documents being named. We describe repertory grids as used in this application and summarize the resulting analysis

Risk of violence from the man involved in the pregnancy after receiving or being denied an abortion.

BackgroundIntimate partner violence is common among women having abortions, with between 6% and 22% reporting recent violence from an intimate partner. Concern about violence is a reason some pregnant women decide to terminate their pregnancies. Whether risk of violence decreases after having an abortion, remains unknown.MethodsData are from the Turnaway Study, a prospective cohort study of women seeking abortions at 30 facilities across the U.S. Participants included women who: presented just prior to a facility's gestational age limit and received abortions (Near Limit Abortion Group, n = 452), presented just beyond the gestational limit and were denied abortions (Turnaways, n = 231), and received first trimester abortions (First Trimester Abortion Group, n = 273). Mixed effects logistic regression was used to assess the relationship between receiving versus being denied abortion and subsequent violence from the man involved in the pregnancy over 2.5 years.ResultsPhysical violence decreased for Near Limits (adjusted odds ratios (aOR), 0.93 per month; 95% Confidence Interval (CI) 0.90, 0.96), but not Turnaways who gave birth (P < .05 versus Near Limits). The decrease for First Trimesters was similar to Near Limits (P = .324). Psychological violence decreased for all groups (aOR, 0.97; CI 0.94, 1.00), with no differential change across groups.ConclusionsPolicies restricting abortion provision may result in more women being unable to terminate unwanted pregnancies, potentially keeping them in contact with violent partners, and putting women and their children at risk

Are the Oxygen Isotope Values of the Late Cretaceous Western Interior Seaway Different from the Open Ocean?

The Western Interior Seaway (WIS) was a North American epicontinental sea that was connected to the open ocean through the passage of the northern Boreal Sea and the southern Tethys Sea from the early Albian (~113 million years ago) to the early Paleogene (~65 million years ago). The WIS began to recced and lost its connection to the southern Tethys Sea in the late Campanian (~72 million years ago). In the early Paleogene, the WIS dried up completely. The oxygen isotopic composition (δ18O) of benthic bivalves was measured from the upper Campanian and lower Maastrichtian (75 million years ago to 69 million years ago) to decipher if the WIS had different δ18O values than the δ18O values of the open ocean. This study would begin to answer the question if the δ18O values of the WIS changed over time since the WIS began to retreat from the open ocean in the late Campanian. We measured δ18O of a variety of well-preserved epifaunal (Anisomyon, Endocostea, Inoceramus, Ostrea, and Pteria) and infaunal (Cucullaea, Cymbophora, Geltena, Lucina, Nucula, and Tenuiptera) bivalves. Then, we compared the δ18O values of the WIS benthic bivalves to a literature search conducted on the δ18O values of WIS bivalves and ammonites and δ18O values of the open ocean foraminifera, bivalves, and ammonites. Most WIS δ18O values range from -6‰ to 0‰ and these δ18O values overlap with the open ocean studies, which range from -5‰ to +2‰. The δ18O values of the WIS are not significantly different than the δ18O values of the open ocean even though the WIS began to lose its connection to the open ocean. However, the WIS does has lower δ18O values than the open ocean and this could possibly be due to freshwater input to the WIS or increased evaporation in the WIS. This systematically collected dataset of bivalve δ18O values may contribute to Late Cretaceous climate models and paleoecological and paleoenvironmental studies