An Extraordinary Example of Photokarren in a Sandstone Cave, Cueva Charles Brewer, Chimantá Plateau, Venezuela: Biogeomorphology on a Small Scale

A distinctive suite of small-scale erosional forms that are oriented towards the light occur close to the entrance of Cueva Charles Brewer, a large cave in a sandstone tepui, in SE Venezuela. These are the third example of photokarren ever studied in the world, the other two being from Borneo and Ireland. They are the only photokarren ever described from sandstone, and the only example from a non-carbonate environment. The host rock is a poorly-lithified unit of the Precambrian quartz arenite of the Roraima Supergroup. The forms are all oriented towards the light at 30° regardless of rock surface orientation. The primary (negative) erosional form is the tube. Coalescence of tubes results in the positive remnant forms of rods, pinnacles, and cones. The final stage is a bumpy, wavy surface of degraded cones. The size of the features varies with erosion rate, and details of the form vary with development stage. The main population averages 4.4 cm in depth, with 55% of the surface eroded. This is divided into 10% tubes, 70% rods, 10% cones, 5% linear valley and 5% wavy lowland. The micro-ecosystem includes many bacteria, diatoms, red algae, green algae, liverworts, and oribatid mites, but, surprisingly, no cyanobacteria. The presence of a surface biofilm inside the forms but not on the remnant rock surface and, in the non-degraded forms, the direct relationship of biomass with depth suggests that biological activity is the dominant control on development. In addition, direct bacterial corrosion was noted. These same features occur to varying extents in the photokarren of Borneo and Ireland, and the model for development that we present provides a unifying theory for all photokarren. (This study also includes the first published petrographic analysis of uppermost unit of the Mataui Formation)

Animal Tracks Urban Communities Action Pack

This guide includes Discovery, Awareness, Action and Appendices

Knowledge economy and the social economy : university support for community enterprise development as a strategy for economic regeneration in distressed regions in Canada and Mexico

Meeting: Triple Helix Conference, 3 Jan. 1996, Amsterdam, N

Rethinking Nursing Care: An Ethnographic Approach to Nurse-Patient Interaction in the Context of a HIV Prevention Programme in Rural Tanzania.

While care has been described as the essence of nursing, it is generally agreed that care is a complex phenomenon that remains elusive. Literature reviews highlight the centrality of nurse-patient interactions in shaping care. In sub-Saharan Africa, where there is a critical shortage of health workers, nurses remain the core of the health workforce, but the quality of the patient care they provide has been questioned. OBJECTIVE: The study explored how care is shaped, expressed and experienced in nurses' everyday communication among HIV positive women in Tanzania. STUDY CONTEXT: Data were collected through a prevention of mother-to-child transmission of HIV programme with a comprehensive community component conducted by a church-run hospital in rural Tanzania. The population is largely agro-pastoral, the formal educational level is low and poverty is rampant. METHODS: An ethnographic approach was employed. Nurses and women enrolled in the prevention of mother-to-child transmission of HIV programme were followed closely over a period of nine months in order to explore their encounters and interactions. FINDINGS AND DISCUSSION: The way care is shaped, expressed and experienced is not globally uniform, and the expectations of what quality care involves differ between settings. In this study the expectations of nurses' instructions and authority, combined with nurses' personal engagement were experienced as caring interactions. The findings from this study demonstrate that the quality of nursing care needs to be explored within the specific historical, socio-cultural context in which it is practised

Previous experience of spontaneous or elective abortion and risk for posttraumatic stress and depression during subsequent pregnancy

Background : Few studies have considered whether elective and/or spontaneous abortion (EAB/SAB) may be risk factors for mental health sequelae in subsequent pregnancy. This paper examines the impact of EAB/SAB on mental health during subsequent pregnancy in a sample of women involved in a larger prospective study of posttraumatic stress disorder (PTSD) across the childbearing year (n=1,581). Methods : Women expecting their first baby completed standardized telephone assessments including demographics, trauma history, PTSD, depression, and pregnancy wantedness, and religiosity. Results : Fourteen percent (n=221) experienced a prior elective abortion (EAB), 13.1% (n=206) experienced a prior spontaneous abortion (SAB), and 1.4% (n=22) experienced both. Of those women who experienced either an EAB or SAB, 13.9% (n=220) appraised the EAB or SAB experience as having been “a hard time” (i.e., potentially traumatic) and 32.6% (n=132) rated it as their index trauma (i.e., their worst or second worst lifetime exposure). Among the subset of 405 women with prior EAB or SAB, the rate of PTSD during the subsequent pregnancy was 12.6% (n−51), the rate of depression was 16.8% (n=68), and 5.4% (n−22) met criteria for both disorders. Conclusions : History of sexual trauma predicted appraising the experience of EAB or SAB as “a hard time.” Wanting to be pregnant sooner was predictive of appraising the experience of EAB or SAB as the worst or second worst (index) trauma. EAB or SAB was appraised as less traumatic than sexual or medical trauma exposures and conveyed relatively lower risk for PTSD. The patterns of predictors for depression were similar. Depression and Anxiety, 2010.© 2010 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77965/1/20714_ftp.pd

The effect of interfacial phenomena on gas solubility measurements in molten salts

The behavior of fission gases in molten fuel salt reactors governs activity transport from the reactor and can also affect the performance of the reactor itself. The gas solubility can be described thermodynamically by Henry’s law. However, the coupling of the condensed and gas phases depends on the interfacial area, which is difficult to measure or even to estimate. Surfaces of materials in the reactor will include disperse phases in the salt and porosity within the structural materials, covering a range of compositions and sizes. These attributes can affect measurements of fundamental properties such as gas solubility. Methods to obtain gas solubility, surface tension, interfacial energies, and bubble gas transport are reviewed. Recent data from manometric experiments are interpreted based on xenon sorption onto salt-wetted quartz

Is missing orographic gravity wave drag near 60°S the cause of the stratospheric zonal wind biases in chemistry–climate models?

Nearly all chemistry–climate models (CCMs) have a systematic bias of a delayed springtime breakdown of the Southern Hemisphere (SH) stratospheric polar vortex, implying insufficient stratospheric wave drag. In this study the Canadian Middle Atmosphere Model (CMAM) and the CMAM Data Assimilation System (CMAM-DAS) are used to investigate the cause of this bias. Zonal wind analysis increments from CMAMDAS reveal systematic negative values in the stratosphere near 608S in winter and early spring. These are interpreted as indicating a bias in the model physics, namely, missing gravity wave drag (GWD). The negative analysis increments remain at a nearly constant height during winter and descend as the vortex weakens, much like orographic GWD. This region is also where current orographic GWD parameterizations have a gap in wave drag, which is suggested to be unrealistic because of missing effects in those parameterizations. These findings motivate a pair of free-runningCMAMsimulations to assess the impact of extra orographicGWDat 608S. The control simulation exhibits the cold-pole bias and delayed vortex breakdown seen in the CCMs. In the simulation with extra GWD, the cold-pole bias is significantly reduced and the vortex breaks down earlier. Changes in resolved wave drag in the stratosphere also occur in response to the extra GWD, which reduce stratospheric SH polar-cap temperature biases in late spring and early summer. Reducing the dynamical biases, however, results in degraded Antarctic column ozone. This suggests that CCMs that obtain realistic column ozone in the presence of an overly strong and persistent vortex may be doing so through compensating errors

Simulated climate change conditions unveil the toxic potential of the fungicide pyrimethanil on the midge Chironomus riparius: a multigeneration experiment

Although it has been suggested that temperature increase may alter the toxic potential of environmental pollutants, few studies have investigated the potential risk of chemical stressors for wildlife under Global Climate Change (GCC) impact. We applied a bifactorial multigeneration study in order to test if GCC conditions alter the effects of low pesticide concentrations on life history and genetic diversity of the aquatic model organism Chironomus riparius. Experimental populations of the species were chronically exposed to a low concentration of the fungicide pyrimethanil (half of the no-observed-adverse-effect concentration: NOAEC/2) under two dynamic present-day temperature simulations (11.0–22.7°C; 14.0–25.2°C) and one future scenario (16.5–28.1°C). During the 140-day multigeneration study, survival, emergence, reproduction, population growth, and genetic diversity of C. riparius were analyzed. Our results reveal that high temperature and pyrimethanil act synergistically on the midge C. riparius. In simulated present-day scenarios, a NOAEC/2 of pyrimethanil as derived from a life-cycle toxicity test provoked only slight-to-moderate beneficial or adverse effects on C. riparius. In contrast, exposure to a NOAEC/2 concentration of pyrimethanil at a thermal situation likely for a summer under GCC conditions uncovered adverse effects on mortality and population growth rate. In addition, genetic diversity was considerably reduced by pyrimethanil in the future scenario, but only slightly under current climatic conditions. Our multigeneration study under near-natural (climatic) conditions indicates that not only the impact of climate change, but also low concentrations of pesticides may pose a reasonable risk for aquatic insects in future