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A new carbon isotope record for two high-latitude sedimentary successions that span the Jurassic–Cretaceous boundary interval in the Sverdrup Basin of Arctic Canada is presented. This study, combined with other published Arctic data, shows a large negative isotopic excursion of organic carbon (δ13Corg) of 4‰ (V-PDB) and to a minimum of −30.7‰ in the probable middle Volgian Stage. This is followed by a return to less negative values of c. −27‰. A smaller positive excursion in the Valanginian Stage of c. 2‰, reaching maximum values of −24.6‰, is related to the Weissert Event. The Volgian isotopic trends are consistent with other high-latitude records but do not appear in δ13Ccarb records of Tethyan Tithonian strata. In the absence of any obvious definitive cause for the depleted δ13Corg anomaly, we suggest several possible contributing factors. The Sverdrup Basin and other Arctic areas may have experienced compositional evolution away from open-marine δ13C values during the Volgian Age due to low global or large-scale regional sea levels, and later become effectively coupled to global oceans by Valanginian time when sea level rose. A geologically sudden increase in volcanism may have caused the large negative δ13Corg values seen in the Arctic Volgian records but the lack of precise geochronological age control for the Jurassic–Cretaceous boundary precludes direct comparison with potentially coincident events, such as the Shatsky Rise. This study offers improved correlation constraints and a refined C-isotope curve for the Boreal region throughout latest Jurassic and earliest Cretaceous time.
This study examined the mediating role of loneliness (assessed by self-report at Time 2; Grade 6) in the relation between early social preference (assessed by peer report at Time 1; kindergarten through Grade 3) and adolescent anxious/depressed symptoms (assessed by mother, teacher, and self-reports at Time 3; Grades 7–9). Five hundred eighty-five boys and girls (48% female; 16% African American) from three geographic sites of the Child Development Project were followed from kindergarten through Grade 9. Loneliness partially mediated and uniquely incremented the significant effect of low social preference in childhood on anxious/depressed symptoms in adolescence, controlling for early anxious/depressed symptoms at Time 1. Findings are critical to understanding the psychological functioning through which early social experiences affect youths' maladjusted development. Directions for basic and intervention research are discussed, and implications for treatment are addressed.
Carbon and oxygen isotope data from a succession of Cretaceous (Barremian–Cenomanian) age recovered from the Pacific Ocean (DSDP site 463) are presented. The carbon isotope curve reveals a large isotope excursion within the early Aptian where δ13C values reach ~4.8‰ in the L. cabri–G. ferreolensis foraminifera zone. A decrease in δ13C values is observed at the base G. algerianus zone, before a return to more positive values at the top of the G. algerianus–T. bejaouaensis zone. The pronounced early Aptian positive event is preceded by a large negative isotope excursion, confined to the G. blowi zone. Synchronous with this excursion are increased total organic carbon values and increases in Mn and Fe concentrations. Integrated biostratigraphic and magnetostratigraphic data, together with the carbon isotope profile, suggest that the organic-rich units of site 463 are correlatable with Oceanic Anoxic Event 1a. The input of isotopically light volcanic CO2 in concert with the intensification and upwelling of intermediate water enriched in 12C could account for the observed trends. A potential trigger may have been the destabilization of the water column and the prodigious CO2 emissions associated with hydrothermal activity and the emplacement of the Ontong Java Plateau. Coupled with faunal evidence, the subsequent positive carbon isotope excursion is interpreted to be resulting from high, but decreasing, productivity and possibly increasing ocean stratification resulting in strong carbon isotopic gradients and 13C-enriched surface waters. The decrease in δ13C within the G. algerianus zone is coincident with more positive δ18O values. If these are interpreted in terms of temperature this interval may be characterized by a period of cooling and possibly a waning of Corg cycling. A return to lower δ13C values during the middle Albian is considered to be related to the increased influence of upwelling, as opposed to a waning of Corg cycling. Upwelling introduced isotopically light carbon to the surface, arresting the stratified oceanic conditions.
Row crop weed management decisions can be complex due to the number of available herbicide treatment options, the multispecies nature of weed infestations within fields, and the effect of soil characteristics and soil-moisture conditions on herbicide efficacy. To assist weed managers in evaluating alternative strategies and tactics, three computer programs have been developed for corn, cotton, peanut, and soybean. The programs, called HADSS (Herbicide Application Decision Support System), Pocket HERB, and WebHADSS, utilize field-specific information to estimate yield loss that may occur if no control methods are used, to eliminate herbicide treatments that are inappropriate for the specified conditions, and to calculate expected yield loss after treatment and expected net return for each available herbicide treatment. Each program has a unique interactive interface that provides recommendations to three distinct kinds of usage: desktop usage (HADSS), internet usage (WebHADSS), and on-site usage (Pocket HERB). Using WeedEd, an editing program, cooperators in several southern U.S. states have created different versions of HADSS, WebHADSS, and Pocket HERB that are tailored to conditions and weed management systems in their locations.
A 27-year-old woman with a post-partum psychosis developed NMS which proved difficult to diagnose because of the organic features of the presenting illness. Possible contributory factors to the development of NMS included exhaustion, a non-specific viral illness, and rapid loading with haloperidol.
Tuberculosis (TB) skin testing practices and the prevalence and inherent risk of TB infection among hospital employees in 167 North Carolina (NC) hospitals were determined from a 79% (132/167) response to a tuberculosis screening questionnaire. Preemployment TB skin testing was performed by 98% of responding hospitals, primarily (87%) by the Mantoux method. TB skin test reactions of ≥ 10 mm were interpreted as significant by 72% and at the appropriate time interval of 48 to 72 hours after administration by 80%. The booster test was routinely performed in 12% of the hospitals. TB infection prevalence among new employees during 1983 was 6.3% (260/4137) in 30 hospitals supplying these data. A positive correlation was noted between employee infection prevalence and county TB case rates (P = .014). Skin test conversion data from 56 hospitals across the state revealed a five year mean conversion rate of 1.14% among 71,253 personnel. There was an association between the incidence of TB in the general population and the frequency of conversions among hospital employees in corresponding geographical regions. Similarly, the incidence of TB among approximately 100,000 NC hospital employees in 1983 and 1984 was less than the incidence in the general population. These associations suggest that the incidence of TB infection among hospital personnel may reflect the prevalence of tuberculosis in the community rather than an occupational hazard. Annual TB skin testing of hospital employees may be justified in eastern North Carolina where the incidence of tuberculosis (22-30 cases/ 100,000) is greater than the national average and where the risk of new TB infection among hospital employees is relatively common (≥1.5%).
Blocks of Cheddar cheese ranging in weight from ¾ to 44 lb were vacuum-wrapped and stored for up to 6 weeks. Panel assessment after 0, 3 and 6 weeks showed that the quality decreased, and off-flavours increased with decrease in block size. Headspace analysis showed that the volatile substances H2S and CH3SH decreased in concentration in line with quality.
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