Soil carbon and nitrogen cycling at the atmosphere-soil interface: Quantifying the responses of biocrust-soil interactions to global change.

In drylands, where water scarcity limits vascular plant growth, much of the primary production occurs at the soil surface. This is where complex macro- and microbial communities, in an intricate bond with soil particles, form biological soil crusts (biocrusts). Despite their critical role in regulating C and N cycling in dryland ecosystems, there is limited understanding of the fate of biologically fixed C and N from biocrusts into the mineral soil, or how climate change will affect C and N fluxes between the atmosphere, biocrusts, and subsurface soils. To address these gaps, we subjected biocrust-soil systems to experimental warming and drought under controlled laboratory conditions, monitored CO2 fluxes, and applied dual isotopic labeling pulses (13CO2 and 15N2). This allowed detailed quantification of elemental pathways into specific organic matter (OM) pools and microbial biomass via density fractionation and phospholipid fatty acid analyses. While biocrusts modulated CO2 fluxes regardless of the temperature regime, drought severely limited their photosynthetic C uptake to the extent that the systems no longer sustained net C uptake. Furthermore, the effect of biocrusts extended into the underlying 1 cm of mineral soil, where C and N accumulated as mineral-associated OM (MAOM<63µm). This was strongly associated with increased relative dominance of fungi, suggesting that fungal hyphae facilitate the downward C and N translocation and subsequent MAOM formation. Most strikingly, however, these pathways were disrupted in systems exposed to warming, where no effects of biocrusts on the elemental composition of the underlying soil nor on MAOM were determined. This was further associated with reduced net biological N fixation under combined warming and drought, highlighting how changing climatic conditions diminish some of the most fundamental ecosystem functions of biocrusts, with detrimental repercussions for C and N cycling and the persistence of soil organic matter pools in dryland ecosystems.

En regiones áridas, donde la sequía limita el crecimiento de plantas vasculares, gran parte de la producción primaria ocurre en la superficie del suelo. En este lugar, complejas comunidades microbianas, estrechamente ligadas a partículas del suelo, forman costras biológicas (conocidas también como biocostras). Aunque estas biocostras son cruciales para regular los ciclos del carbono (C) y nitrógeno (N) en ecosistemas áridos, aún existe una comprensión limitada del destino hacia el suelo mineral del C y N fijados biológicamente desde las biocostras, o sobre cómo el cambio climático afectará los flujos de C y N entre la atmósfera, las biocostras y los suelos subsuperficiales. Para abordar estas brechas, sometimos sistemas de biocostra y suelo a aumentos de temperatura y sequía experimentales en condiciones controladas de laboratorio, donde monitoreamos los flujos de CO2 y aplicamos pulsos de etiquetado isotópico dual (13CO2 y 15N2). Esto permitió una cuantificación detallada de las vías de incorporación de los elementos en grupos específicos de materia orgánica (MO) y biomasa microbiana mediante fraccionamiento por densidad y análisis de ácidos grasos de fosfolípidos (PLFA). Si bien las biocostras modularon los flujos de CO2 independientemente del régimen de la temperatura, la sequía restringió severamente la captación fotosintética de C hasta el punto de que los sistemas ya no mantuvieron la absorción neta de C. Además, el efecto de las biocostras se extendió hasta 1 cm del suelo bajo esta, donde el C y el N se acumularon como MO asociada a minerales (MAOM<63µm). Esto se relaciona estrechamente con un aumento en la dominancia relativa de hongos, lo que sugiere que las hifas de los hongos facilitan la translocación descendente de C y N y subsecuentemente la formación de MAOM. Sin embargo, lo más sorprendente es que estas vías se vieron interrumpidas en sistemas expuestos al aumento de temperatura, donde no se determinaron efectos de las biocostras en la composición elemental del suelo subyacente ni en la MAOM. Esto se asoció con una reducción de la fijación biológica neta de N bajo el efecto combinado del aumento de la temperatura y la sequía, destacando cómo las condiciones climáticas cambiantes disminuyen algunas de las funciones ecosistémicas más fundamentales de las biocostras, con repercusiones perjudiciales para el ciclo de C y N y la persistencia de los depósitos de MOS en los ecosistemas áridos.

Carbonate ooids of the Mesoarchaean Pongola Supergroup, South Africa.

Ooids from the Mesoarchaean Chobeni Formation, Pongola Supergroup, KwaZulu-Natal, South Africa are older than any ooids reported to date. They are made of dolomite and ankerite and show concentric, radial-concentric, micritic, and radial fabrics. Radial ooids are interpreted to have originated from high-Mg-calcite and probably formed by microbial activity in a low-energy regime, while concentric ooids had an aragonite precursor and formed biotically under agitated/high-energy environmental conditions. Micritic ooids formed via the recrystallization of concentric ooids. Ooids and other allochems, such as intraclasts and peloids, contain carbonaceous matter. The close association of carbonaceous matter within ooid cortices with metabolically important elements, such as N, S and P, as identified by nano-scale secondary ion mass spectrometry analysis, allows us to propose a biologically induced origin for some ooids. By analogy with modern examples, a variety of microbial communities probably played a role in carbonate precipitation and ooid formation. Shale-normalized rare earth element (REE) distribution patterns of ooids and other allochems show positive LaSN , GdSN and YSN anomalies, superchondritic Y/Ho ratios and depleted light rare earth elements (LREEs) relative to the heavy rare earth elements (HREEs), which resemble those of seawater. These anomalies are less pronounced than expected for an open marine setting, which is interpreted as evidence for deposition in restricted shallow marine environments. Non-seawater REE patterns in recrystallized matrix and pore- and vein-filling carbonate likely reflect redistribution of rare earth elements during post-depositional alteration and/or reflect differences in the elemental and REE compositions of diagenetic fluids.

Archaeal and bacterial communities across a chronosequence of drained lake basins in Arctic Alaska.

We examined patterns in soil microbial community composition across a successional gradient of drained lake basins in the Arctic Coastal Plain. Analysis of 16S rRNA gene sequences revealed that methanogens closely related to Candidatus 'Methanoflorens stordalenmirensis' were the dominant archaea, comprising >50% of the total archaea at most sites, with particularly high levels in the oldest basins and in the top 57 cm of soil (active and transition layers). Bacterial community composition was more diverse, with lineages from OP11, Actinobacteria, Bacteroidetes, and Proteobacteria found in high relative abundance across all sites. Notably, microbial composition appeared to converge in the active layer, but transition and permafrost layer communities across the sites were significantly different to one another. Microbial biomass using fatty acid-based analysis indicated that the youngest basins had increased abundances of gram-positive bacteria and saprotrophic fungi at higher soil organic carbon levels, while the oldest basins displayed an increase in only the gram-positive bacteria. While this study showed differences in microbial populations across the sites relevant to basin age, the dominance of Candidatus 'M. stordalenmirensis' across the chronosequence indicates the potential for changes in local carbon cycling, depending on how these methanogens and associated microbial communities respond to warming temperatures.

Cross-cultural differences in rating hyperactive-disruptive behaviors in children.

OBJECTIVE: To determine the extent to which the reported variations across countries in the prevalence of attention-deficit hyperactivity disorder are due to cultural differences among raters, the authors examined the degree to which mental health professionals in four countries differed in their ratings of hyperactive-disruptive behaviors in children. METHOD: Mental health professionals from China (N = 8), Indonesia (N = 12), Japan (N = 9), and the United States (N = 8) rated the presence and degree of hyperactive-disruptive behaviors in standardized videotape vignettes of four 8-year-old boys participating in individual and group activities. RESULTS: Chinese and Indonesian clinicians gave significantly higher scores for hyperactive-disruptive behaviors than did their Japanese and American colleagues. CONCLUSIONS: These findings suggest that perceptions of hyperactivity vary significantly across countries even if uniform rating criteria are applied. Without correction for these perceptual differences, cross-cultural prevalence rates of hyperactivity may not be comparable.

Alcohol enhancement of human memory: tests of consolidation and interference hypotheses.

Two hypotheses about the phenomenon of alcohol-enhanced human memory were investigated. Whereas a consolidation account of this phenomenon indicates that continued processing of a target memory is facilitated by alcohol, an interference account states that the alcohol main effect is to impair the acquisition of potentially interfering new memories. No support was found for the consolidation view in an experiment manipulating (1) the length of time items preceded drug administration, (2) the amount of postpresentation processing each item received, and (3) the type of memory test employed. In line with expectations derived from interference theory, retention was substantially improved only for recall and not for tests of recognition memory.

Job satisfaction and workplace characteristics of primary and specialty care physicians at a bimodal medical school.

PURPOSE: A few medical schools are highly successful in obtaining research funding and producing primary care physicians. The authors compared the job satisfaction of primary and specialty care faculty at one of these bimodal schools. METHODS: In 1998, all full-time physician-faculty (n = 408) in 15 clinical departments at the University of Iowa College of Medicine (a bimodal medical school) were sent a questionnaire based on the Price-Mueller model of job satisfaction. Faculty rated their global job satisfaction and perceptions about 18 workplace characteristics, stressors, and supports. Responses of primary and specialty care physicians were compared in these domains. RESULTS: A total of 71% of surveyed faculty (n = 341) returned usable questionnaires. Primary and specialty care faculty reported similar levels of job satisfaction (p =.20), and similar percentages (51% versus 54%, p =.63) reported overall satisfaction with their jobs at the medical school. However, primary care faculty perceived less opportunity to advance (p <.01), greater professional-role ambiguity (p =.02), less collegiality (p =.02), and less ability to make full use of their clinical skills (p =.01). Primary and specialty care faculty reported similar intentions of leaving the medical school within the coming year (p =.41). CONCLUSIONS: Primary and specialty care physicians at one bimodal medical school reported similar levels of job satisfaction. However, the primary care physicians rated several important job-related domains lower than did their specialty care colleagues, most notably the opportunity to advance within the medical school.

HIV-related training programs for health care professionals: findings from a collaborative assessment.

Seeking to avoid duplication of effort, evaluators from twelve separate HIV-related training programs worked together to share information, assessment tools, measurement instruments, and preliminary findings across programs. Each training program focused on preparing health care professionals to meet the growing demands of the AIDS epidemic and specifically address psychosocial issues of care. The collaborative effort of program evaluators included an examination of experiences across programs and yielded recommendations for needs assessments, process evaluation procedures, and outcome measures. This paper focuses on the findings from an analysis of needs assessments and process evaluations across twelve HIV-related training programs in eleven areas of the country.

Factors associated with primary care residents' satisfaction with their training.

BACKGROUND AND OBJECTIVES: Satisfaction is known to impact work performance, learning, recruitment, and retention. This study identifies the factors associated with primary care residents' satisfaction with their training. METHODS: We used a cross-sectional survey based on the Price-Mueller model of job satisfaction. The model included 14 job characteristics, four personal characteristics, and four demographic factors. Data were collected in February and March 1996 from residents in three primary care training programs (family practice, pediatrics, and internal medicine) at a large academic medical center. The same standardized, self-administered questionnaires were used in all three departments. RESULTS: Seventy-five percent (n = 119) of the residents returned questionnaires. Five job characteristics were positively associated with resident satisfaction: continuity of care, autonomy, collegiality, work that encourages professional growth, and work group loyalty. Role conflict, a sixth job characteristic, was negatively associated with satisfaction. The personal characteristic of having an optimistic outlook on life was also positively associated with satisfaction. The model explained 66% of the variation in self-reported satisfaction. CONCLUSIONS: The satisfaction of the residents was significantly associated with six job characteristics and one personal factor. Interventions based on these job characteristics may increase resident satisfaction and may lead to better patient outcomes, better work performance, greater patient satisfaction, and more success in recruiting top students into a residency.

A causal model for turnover for nurses.

Longitudinal data on 1,091 registered nurses in seven hospitals were used to estimate a causal model of turnover in organizations. Total effects on turnover were found to be the greatest for four determinants: intent to stay, opportunity, general training, and job satisfaction. The relative importance of the determinants of turnover and the explanatory power of the model are presented and discussed.

Nursing faculty and students' attitudes regarding HIV.

A multidisciplinary group of health professional educators examined the faculty and student attitudes related to AIDS in undergraduate and graduate nursing programs and in a dental hygiene program. Results indicated consistent differences in attitudes toward homosexuality and intravenous drug users, AIDS-phobia, AIDS-related work stress, and willingness to work with HIV, homosexual, or intravenous-drug-using patients among faculty, undergraduate, and graduate nursing students, and certificate-level dental hygiene students. Faculty and master's-level nursing students consistently indicated the most positive attitudes and behavioral intentions. A one-year follow-up of a sample of undergraduate students revealed little change in these attitudes or behavioral intentions. Implications of these findings for nursing educators are discussed.

Teen perspectives on HIV and the relevance of Hawaii's health providers.

Based on focus group interviews with adolescents from an urban Honolulu community, the present article describes how these adolescents view HIV, HIV-prevention and the role of health care providers in addressing HIV-related needs. Although medical providers are known to be knowledgeable experts in a variety of health care areas, other research points to an underutilization of this potential. While knowledgeable about HIV, many of the youth in this study continue to engage in risky behavior. Few perceive they have others they can meaningfully talk to about their HIV and other health concerns. Even when probed for, almost none of these teens saw health care providers as pertinent to HIV or their health beyond the traditional illness/prescription role. Suggestions for ways to get more involved in the prevention of HIV and, more generally, positive health development in teens are discussed.

Mechanisms of motor vehicle crashes related to burns--an analysis of the German In depth Accident Study (GIDAS) database.

BACKGROUND: Patients of motor vehicle crashes (MVCs) suffering burns are challenging for the rescue team and the admitting hospital. These patients often face worse outcomes than crash patients with trauma only. Our analysis of the German In-depth Accident Study (GIDAS) database researches the detailed crash mechanisms to identify potential prevention measures. METHODS: We analyzed the 2011 GIDAS database comprising 14,072 MVC patients and compared individuals with (Burns) and without (NoBurns) burns. Only complete data sets were included. Patients with burns obviously resulting of air bag deployment only were not included in the Burns group. Data acquisition by an on call team of medical and technical researchers starts at the crash scene immediately after the crash and comprises technical data as well as medical information until discharge from the hospital. Statistical analysis was done by Mann-Whitney-U-test. Level of significance was p < 0.05. RESULTS: 14,072 MVC patients with complete data sets were included in the analysis. 99 individuals suffered burns (0.7%; group "Burns"). Demographic data and injury severity showed no statistical significant difference between the two groups of Burns and NoBurns. Injury severity was measured using the Injury Severity Score (ISS). Direct frontal impact (Burns: 48.5% vs. NoBurns: 33%; p < 0.05) and high-energy impacts as represented by delta-v (m/s) (Burns: 33.5 ± 21.4 vs. NoBurns: 25.2 ± 15.9; p < 0.05) were significantly different between groups as was mortality (Burns: 12.5% vs. NoBurns: 2.1%; p < 0.05). Type of patients' motor vehicles and type of crash opponent showed no differences. CONCLUSIONS: Our results show, that frontal and high-energy impacts are associated with a frequency of burns. This may serve automobile construction companies to improve the burn safety to prevent flames spreading from the motor compartment to the passenger compartment. Communities may impose speed limits in local crash hot spots.

Growth and physiology of olive pioneer and fibrous roots exposed to soil moisture deficits.

In woody plants, pioneer roots are the main roots used to expand the root system horizontally and vertically whereas fibrous 'feeder' roots are chiefly used in the absorption of water and nutrients. Because of their different roles, we expected newly emerged pioneer and fibrous roots to respond differently to restrictions in soil moisture. We hypothesized that fibrous roots would exhibit greater growth plasticity and greater physiological impairment from soil moisture deficits, especially under heterogeneous conditions. We compared the responses of fibrous and pioneer roots of olive seedlings (Olea europaea) to localized and uniform soil moisture deficits in transparent containers in the greenhouse. In comparison with uniformly wet conditions, uniformly dry conditions caused reduced shoot photosynthesis and reduced shoot growth, but no significant effect on root morphology, root respiration (measured in aerated buffer solution using excised roots) or electrolyte leakage as a function of root age. Under heterogeneous soil moisture conditions, root growth tended to preferentially occur in the moist sector, especially in the pioneer roots. In comparison with pioneer roots in the moist sector, pioneer roots in the dry sector had higher tissue density and higher suberin content, but no shift in root respiration, non-structural carbohydrates or electrolyte leakage. In contrast, fibrous roots in the dry sector exhibited evidence of impaired physiology in older (>38 days) roots compared with similar age fibrous roots in the moist sector. While we anticipated that, compared with pioneer roots, fibrous roots would be more sensitive to soil moisture deficits as expressed by higher electrolyte leakage, we did not expect the strong growth plasticity of pioneer roots under heterogeneous soil moisture conditions. Differentiating the responses of these two very different root types can improve our understanding of how different portions of the root system of woody plants cope with soil moisture deficits.

Nurses' job satisfaction: a longitudinal analysis.

A causal model of nurses' job satisfaction was tested using longitudinal analysis of 13 causal determinants and five correlates measured at Time 1, and job satisfaction measured at Time 2. Data were collected from 370 registered nurses at five hospitals using questionnaires mailed eight months apart. Four different models were analyzed using the LISREL maximum likelihood procedure to estimate the path coefficients. Variables reaching statistically significant levels included, in order of importance, routinization, promotional opportunity, distributive justice, age, day shift, workload, kinship responsibility, and opportunity for jobs outside the employing hospital. With the prior level of job satisfaction controlled, only the effects of day shift remained significant.

Nurses' job satisfaction: a proposed measure.

Thirty-three items originally developed to measure three dimensions of nurses' job satisfaction were subjected to a series of checks designed to determine the number of dimensions being measured and the reliability and validity of the measures of these dimensions. Although the hypothesis of only three dimensions was not supported, the eight interpretable factors that did emerge could meaningfully be placed within these three dimensions. The eight factors were satisfaction with extrinsic rewards, scheduling, family/work balance, co-workers, interaction, professional opportunities, praise/recognition, and control/responsibility. Internal consistency and test-retest reliabilities are reported, as well as checks for criterion-related and construct validity.