883 research outputs found
Bioaccumulation surveillance in Milford Haven Waterway
Biomonitoring of contaminants (metals, organotins, PAHs, PCBs) was
carried out along the Milford Haven Waterway (MHW) and at a reference site in the
Tywi Estuary during 2007-2008. The species used as bioindicators encompass a
variety of uptake routes - Fucus vesiculosus (dissolved contaminants); Littorina
littorea (grazer); Mytilus edulis and Cerastoderma edule (suspension feeders); and
Nereis diversicolor (omnivore which often reflects contaminants in sediment).
Differences in feeding strategy and habitat preference have subtle implications for
bioaccumulation trends though, with few exceptions, contaminant body burdens in
Milford Haven (MH) were higher than those at the Tywi reference site, reflecting
inputs.
Elevated concentrations of metals were occasionally observed at individual MH sites,
whilst As and Se (molluscs and seaweed) were, for much of MHW, consistently at the
higher end of the UK range. However, for the majority of metals, distributions in MH
biota were not exceptional by UK standards. Several metal-species combinations
indicated increases in bioavailability at upstream sites, which may reflect the
influence of geogenic or other land-based sources – perhaps enhanced by lower
salinity (greater proportions of more bioavailable forms).
TBT levels in MH mussels were below OSPAR toxicity thresholds and in the Tywi
were close to zero. Phenyltins were not accumulated appreciably in Mytilus, whereas
some Nereis populations may have been subjected to localized (historical) sources.
PAHs in Nereis tended to be evenly distributed across most sites, but with somewhat
higher values at Dale for acenaphthene, fluoranthene, pyrene, benzo(a)anthracene and
chrysene; naphthalenes tended to be enriched further upstream in the mid-upper
Haven (a pattern seen in mussels for most PAHs). Whilst concentrations in MH
mussels were mostly above reference site and OSPAR backgrounds, it is unlikely that
ecotoxicological guidelines would be exceeded.
PCBs in mussels were between upper and lower OSPAR guidelines and were unusual
in their distribution in that highest levels occurred at the mouth of MH.
Condition indices (CI) of bivalves (mussels and cockles) were highest at the Tywi
reference site and at the seaward end of MH, decreasing upstream along the
Waterway. There were a number of significant (negative) relationships between CI
and body burdens and multivariate analysis indicated that a combination of
contaminants could influence the pattern in condition (and sub-lethal responses such
as MT and TOSC) across sites. Cause and effect needs to be tested more rigorously in
future assessments
Dynamics of Strongly Interacting Fermi Gases of Atoms in a Harmonic Trap
Dynamics of strongly interacting trapped dilute Fermi gases is investigated
at zero temperature. As an example of application we consider the expansion of
the cloud of fermions initially confined in an anisotropic harmonic trap, and
study the equation of state dependence of the radii of the trapped cloud and
the collective oscillations in the vicinity of a Feshbach resonance.Comment: 11 pages, 3 figures. Published versio
Traces of stimulated bosonic exciton-scattering in semiconductor luminescence
We observe signatures of stimulated bosonic scattering of excitons, a
precursor of Bose-Einstein-Condensation (BEC), in the photoluminescence of
semiconductor quantum wells. The optical decay of a spinless molecule of two
excitons (biexciton) into an exciton and a photon with opposite angular momenta
is subject to bosonic enhancement in the presence of other excitons. In a spin
polarized gas of excitons the bosonic enhancement breaks the symmetry of two
equivalent decay channels leading to circularly polarized luminescence of the
biexciton with the sign opposite to the excitonic luminescence. Comparison of
experiment and many body theory proves stimulated scattering of excitons, but
excludes the presence of a fully condensed BEC-like state.Comment: 5 page
Experience of an Abdominal Aortic Aneurysm in a Patient Having Crossed Ectopia with Fusion Anomaly of the Kidney
We report a case of surgically treated abdominal aortic aneurysm (AAA) in a patient having crossed ectopia with fusion anomaly of the kidney. One artery from the abdominal aorta above the aneurysm supplies the right kidney while three renal arteries (two from the aneurysm itself and one from the left common iliac artery) supply the crossed ectopic kidney. Preoperative imaging to define the arterial and collecting systems along with a detailed planning of the operation is essential to prevent ischemic renal injury as well as ureteral injury during AAA repair
Assessment of foodservice quality and identification of improvement strategies using hospital foodservice quality model
The purposes of this study were to assess hospital foodservice quality and to identify causes of quality problems and improvement strategies. Based on the review of literature, hospital foodservice quality was defined and the Hospital Foodservice Quality model was presented. The study was conducted in two steps. In Step 1, nutritional standards specified on diet manuals and nutrients of planned menus, served meals, and consumed meals for regular, diabetic, and low-sodium diets were assessed in three general hospitals. Quality problems were found in all three hospitals since patients consumed less than their nutritional requirements. Considering the effects of four gaps in the Hospital Foodservice Quality model, Gaps 3 and 4 were selected as critical control points (CCPs) for hospital foodservice quality management. In Step 2, the causes of the gaps and improvement strategies at CCPs were labeled as "quality hazards" and "corrective actions", respectively and were identified using a case study. At Gap 3, inaccurate forecasting and a lack of control during production were identified as quality hazards and corrective actions proposed were establishing an accurate forecasting system, improving standardized recipes, emphasizing the use of standardized recipes, and conducting employee training. At Gap 4, quality hazards were menus of low preferences, inconsistency of menu quality, a lack of menu variety, improper food temperatures, and patients' lack of understanding of their nutritional requirements. To reduce Gap 4, the dietary departments should conduct patient surveys on menu preferences on a regular basis, develop new menus, especially for therapeutic diets, maintain food temperatures during distribution, provide more choices, conduct meal rounds, and provide nutrition education and counseling. The Hospital Foodservice Quality Model was a useful tool for identifying causes of the foodservice quality problems and improvement strategies from a holistic point of view
Effects of hyperlinks on navigation in virtual environments
Hyperlinks introduce discontinuities of movement to 3-D virtual environments (VEs). Nine independent attributes of hyperlinks are defined and their likely effects on navigation in VEs are discussed. Four experiments are described in which participants repeatedly navigated VEs that were either conventional (i.e. obeyed the laws of Euclidean space), or contained hyperlinks. Participants learned spatial knowledge slowly in both types of environment, echoing the findings of previous studies that used conventional VEs. The detrimental effects on participants' spatial knowledge of using hyperlinks for movement were reduced when a time-delay was introduced, but participants still developed less accurate knowledge than they did in the conventional VEs. Visual continuity had a greater influence on participants' rate of learning than continuity of movement, and participants were able to exploit hyperlinks that connected together disparate regions of a VE to reduce travel time
The antioxidant and chemopreventive potentialities of Mosidae (Adenophora remotiflora) leaves
Our study focused on the antioxidant activities of Mosidae leaf ethanol extract (MLE) and included measurements of reducing power, total phenolic compounds, DPPH radical scavenging activity, and hydroxyl radical scavenging activity. In order to determine whether or not MLE evidences any chemopreventive activities, experimental lung metastasis was induced via the i.v. inoculation of colon26-M3.1 carcinoma cells into BALB/c mice. Additionally, we attempted to characterize any possible cytotoxic effects in murine normal splenocytes and tumor cells (B16-BL6 and colon26-M3.1). The total phenolic content and reducing capacity were measured at 39 mg/100 mL and 1.24, respectively, whereas the DPPH and hydroxyl radical scavenging activities of MLE were measured to be 88.89% and 22.10%, respectively. Prophylactic i.v. treatment with MLE resulted in a dose-dependent and significant inhibition of lung metastasis. Specifically, a MLE dose of 200 ug per mouse resulted in an 88.90% inhibition of lung metastasis. For the cytotoxicity assay, MLE doses up to 100 ug/mL were not shown to affect the growth of normal murine splenocytes. Additionally, the survival of normal cells was not affected at MLE doses below 500 ug/mL. However, MLE doses up to 500 ug/mL reduced the percentage of tumor cell growth for B16BL6 (67% alive) and colon26-M3.1 (62% alive) cells
The Australian public's preferences for emergency care alternatives and the influence of the presenting context: a discrete choice experiment
Objectives The current study seeks to quantify the Australian public's preferences for emergency care alternatives and determine if preferences differ depending on presenting circumstances. Setting Increasing presentations to emergency departments have led to overcrowding, long waiting times and suboptimal health system performance. Accordingly, new service models involving the provision of care in alternative settings and delivered by other practitioners continue to be developed. Participants A stratified sample of Australian adults (n=1838), 1382 from Queensland and 456 from South Australia, completed the survey. This included 951 females and 887 males from the 2045 people who met the screening criteria out of the 4354 people who accepted the survey invitation. Interventions A discrete choice experiment was used to elicit preferences in the context of one of four hypothetical scenarios: a possible concussion, a rash/asthma-related problem involving oneself or one's child and an anxiety-related presentation. Mixed logit regression was used to analyse the dependent variable choice and identify the relative importance of care attributes and the propensity to access care in each context. Results Results indicated a preference for treatment by an emergency physician in hospital for possible concussion and treatment by a doctor in ambulatory settings for rash/asthma-related and anxiety-related problems. Participants were consistently willing to wait longer before making trade-offs in the context of the rash/asthma-related scenario compared with when the same problem affected their child. Results suggest a clear preference for lower costs, shorter wait times and strong emphasis on quality care; however, significant preference heterogeneity was observed. Conclusions This study has increased awareness that the public's emergency care choices will differ depending on the presenting context. It has further demonstrated the importance of service quality as a determinant of healthcare choices. The findings have also provided insights into the Australian public's reactions to emergency care reforms
Cool core remnants in galaxy clusters
X ray clusters are conventionally divided into two classes: "cool core" (CC)
and "non cool core" (NCC) objects, on the basis of the observational properties
of their central regions. Recent results have shown that the cluster population
is bimodal (Cavagnolo et al. 2009). We want to understand whether the observed
distribution of clusters is due to a primordial division into two distinct
classes rather than to differences in how these systems evolve across cosmic
time. We systematically search the ICM of NCC clusters in a subsample of the
B55 flux limited sample of clusters for regions which have some characteristics
typical of cool cores, namely low entropy gas and high metal abundance We find
that most NCC clusters in our sample host regions reminiscent of CC, i. e.
characterized by relative low entropy gas (albeit not as low as in CC systems)
and a metal abundance excess. We have dubbed these structures "cool core
remnants", since we interpret them as what remains of a cool core after a
heating event (AGN giant outbursts in a few cases and more commonly mergers).
We infer that most NCC clusters have undergone a cool core phase during their
life. The fact that most cool core remnants are found in dynamically active
objects provides strong support to scenarios where cluster core properties are
not fixed "ab initio" but evolve across cosmic time.Comment: Accepted for publication in Astronomy & Astrophysics. Version with
full resolution figures available at:
http://www.iasf-milano.inaf.it/~rossetti/public/CCR/rossetti.pd
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