To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Laser–solid interactions are highly suited as a potential source of high energy X-rays for nondestructive imaging. A bright, energetic X-ray pulse can be driven from a small source, making it ideal for high resolution X-ray radiography. By limiting the lateral dimensions of the target we are able to confine the region over which X-rays are produced, enabling imaging with enhanced resolution and contrast. Using constrained targets we demonstrate experimentally a
X-ray source, improving the image quality compared to unconstrained foil targets. Modelling demonstrates that a larger sheath field envelope around the perimeter of the constrained targets increases the proportion of electron current that recirculates through the target, driving a brighter source of X-rays.
Studies have consistently shown that subthreshold depression is associated with an increased risk of developing major depression. However, no study has yet calculated a pooled estimate that quantifies the magnitude of this risk across multiple studies.
We conducted a systematic review to identify longitudinal cohort studies containing data on the association between subthreshold depression and future major depression. A baseline meta-analysis was conducted using the inverse variance heterogeneity method to calculate the incidence rate ratio (IRR) of major depression among people with subthreshold depression relative to non-depressed controls. Subgroup analyses were conducted to investigate whether IRR estimates differed between studies categorised by age group or sample type. Sensitivity analyses were also conducted to test the robustness of baseline results to several sources of study heterogeneity, such as the case definition for subthreshold depression.
Data from 16 studies (n = 67 318) revealed that people with subthreshold depression had an increased risk of developing major depression (IRR = 1.95, 95% confidence interval 1.28–2.97). Subgroup analyses estimated similar IRRs for different age groups (youth, adults and the elderly) and sample types (community-based and primary care). Sensitivity analyses demonstrated that baseline results were robust to different sources of study heterogeneity.
The results of this study support the scaling up of effective indicated prevention interventions for people with subthreshold depression, regardless of age group or setting.
Introduction: Some non-urgent/low-acuity Emergency Department (ED) presentations are considered convenience visits and potentially avoidable with improved access to primary care services. This study surveyed patients who presented to the ED and explored their self-reported reasons and barriers for not being connected to a primary care provider (PCP). Methods: Patients aged 17 years and older were randomly selected from electronic registration records at three urban EDs in Edmonton, Alberta (AB), Canada. Following initial triage, stabilization, and verbal informed consent, patients completed a 47-item questionnaire. Data from the survey were cross-referenced to a minimal patient dataset consisting of ED and demographic information. The questionnaire collected information on patient characteristics, their connection to a PCP, and patients' reasons for not having a PCP. Results: Of the 2144 eligible patients, 1408 (65.7%) surveys were returned and 1402 (65.4%) were completed. The majority of patients (74.4%) presenting to the ED reported having a family physician; however, the ‘closeness’ of the connection to their family physician varied greatly among ED patients with the most recent family physician visit ranging from 1 hour before ED presentation to 45 years prior. Approximately 25% of low acuity ED patients reported no connection with a family physician. Reasons for a lack of PCP connection included: prior physician retired, left, or died (19.8%), they had never tried to find one (19.2%), they had recently moved to Alberta (18.0%), and they were unable to find one (16.5%). Conclusion: A surprisingly high proportion of ED patients (25.6%) have no identified PCP. Patients had a variety of reasons for not having a family physician. These need to be understood and addressed in order for primary care access to successfully contribute to diverting non-urgent, low acuity presentations from the ED.
Introduction: Some low acuity Emergency Department (ED) presentations are considered non-urgent or convenience visits and potentially avoidable with improved access to primary care. This study explored self-reported reasons why non-urgent patients presented to the ED. Methods: Patients, 17 years and older, were randomly selected from electronic registration records at three urban EDs in Edmonton, Alberta (AB), Canada during weekdays (0700 to 1900). A 47-item questionnaire was completed by each consenting patient, which included items on whether the patient believed the ED was their best care option and the rationale supporting their response. A thematic content analysis was performed on the responses, using previous experience and review of the literature to identify themes. Results: Of the 2144 eligible patients, 1408 (65.7%) questionnaires were returned, and 1402 (65.4%) were analyzed. For patients who felt the ED was their best option (n = 1234, 89.3%), rationales included: safety concerns (n = 309), effectiveness of ED care (n = 284), patient-centeredness of ED (n = 277), and access to health care professionals in the ED (n = 204). For patients who felt the ED was not their best care option (n = 148, 10.7%), rationales included a perception that: access to health professionals outside the ED was preferable (n = 39), patient-centeredness (particularly timeliness) was lacking in the ED (n = 26), and their health concern was not important enough to require ED care (n = 18). Conclusion: Even during times when alternative care options are available, the majority of non-urgent patients perceived the ED to be the most appropriate location for care. These results highlight that simple triage scores do not accurately reflect the appropriateness of care and that understanding the diverse and multi-faceted reasons for ED presentation are necessary to implement strategies to support non-urgent, low acuity care needs.
The deterioration of the cholinergic system in aging is hypothesized to contribute to age-related declines in attention. We investigated potential age differences in performance on the Attention Network Test (ANT) and intra-individual variability in speed (RT-IIV) on go/no-go and choice reaction time tasks in young and healthy older adults. We also asked whether short-latency afferent inhibition (SAI), a neurophysiological marker of central cholinergic activity obtained via transcranial magnetic stimulation, might be correlated with performance. Older adults were slower on the ANT and exhibited greater RT-IIV than young adults on the multiple choice RT task, but there were no age differences on the ANT network scores (alerting, orienting, and executive control). SAI was diminished in older adults, but it was not significantly correlated with performance. It may only be in cases of severe cholinergic dysfunction that relations with attention emerge. Other brain mechanisms may also be stronger predictors of functions relating to attention.
Increasing evidence shows attachment security influences symptom expression and adaptation in people diagnosed with schizophrenia and other psychoses.
To describe the distribution of secure and insecure attachment in a cohort of individuals with first-episode psychosis, and to explore the relationship between attachment security and recovery from positive and negative symptoms in the first 12 months.
The study was a prospective 12-month cohort study. The role of attachment, duration of untreated psychosis (DUP), baseline symptoms and insight in predicting and mediating recovery from symptoms was investigated using multiple regression analysis and path analysis.
Of the 79 participants, 54 completed the Adult Attachment Interview (AAI): 37 (68.5%) were classified as insecure, of which 26 (48.1%) were insecure/dismissing and 11 (20.4%) insecure preoccupied. Both DUP and insight predicted recovery from positive symptoms at 12 months. Attachment security, DUP and insight predicted recovery from negative symptoms at 12 months.
Attachment is an important construct contributing to understanding and development of interventions promoting recovery following first-episode psychosis.
Increasing human occupation of the Brazilian Amazon has led to the intensification of deforestation over the last 50 years. The present study is aimed at analysing the impacts of the first year of slash-and-burn cultivation on soil physicochemical properties. Sampling was done in 26 small-scale farms of the Tapajós River basin. In August 2004, soil samples were collected from primary forest plots planned for slash-and-burn cultivation. In September 2005, 1 year after the initial burning and the beginning of cultivation, the same sites were re-sampled. The results indicated that soil fertility after burning was relatively moderate, as the increase of base cations was not particularly marked. Moreover, although an increase of some nutrients (such as exchangeable phosphorus) was observed at soil surface, total carbon and nitrogen (N) pools did not change significantly. Nutrient leaching was also detected through the accumulation of both forms of available nitrogen (NO3 and NH4) as well as potassium in subsoil horizons. In addition, signs of erosion were seen, as a significant increase surface density occurred, coupled with up to 25% fine particle loss at the surface. The present study draws attention to the early impacts of slash-and-burn agriculture on soil properties within a year of cultivation. Furthermore, its regional dimension highlights undisturbed soils natural variability as well as differentiated responses to deforestation according to soil texture.
Few studies have prospectively investigated psychological morbidity in UK head and neck cancer patients. This study aimed to explore changes in psychological symptoms over time, and associations with patients' tumour and treatment characteristics, including toxicity.
Two hundred and twenty patients were recruited to complete the Hospital Anxiety and Depression Scale and the Late Effects on Normal Tissue (Subjective, Objective, Management and Analytic) (‘LENT-SOMA’) questionnaires, both pre- and post-treatment.
Anxiety was highest pre-treatment (38 per cent) and depressive symptoms peaked at the end of treatment (44 per cent). Anxiety significantly decreased and depression significantly increased, comparing pre- versus post-treatment responses (p < 0.001). Hospital Anxiety and Depression Scale scores were significantly correlated with toxicity, age and chemotherapy (p < 0.01 for all).
This is the first study to analyse the relationship between Hospital Anxiety and Depression Scale scores and toxicity scores in head and neck cancer patients. It lends support for the use of the Hospital Anxiety and Depression Scale and the Late Effects on Normal Tissue (Subjective, Objective, Management and Analytic) questionnaire in routine clinical practice; furthermore, continued surveillance is required at multiple measurement points.
Both fish oil (FO) and curcumin have potential as anti-tumour and anti-inflammatory agents. To further explore their combined effects on dextran sodium sulphate (DSS)-induced colitis, C57BL/6 mice were randomised to four diets (2 × 2 design) differing in fatty acid content with or without curcumin supplementation (FO, FO+2 % curcumin, maize oil (control, MO) or MO+2 % curcumin). Mice were exposed to one or two cycles of DSS in the drinking-water to induce either acute or chronic intestinal inflammation, respectively. FO-fed mice exposed to the single-cycle DSS treatment exhibited the highest mortality (40 %, seventeen of forty-three) compared with MO with the lowest mortality (3 %, one of twenty-nine) (P = 0·0008). Addition of curcumin to MO increased (P = 0·003) mortality to 37 % compared with the control. Consistent with animal survival data, following the one- or two-cycle DSS treatment, both dietary FO and curcumin promoted mucosal injury/ulceration compared with MO. In contrast, compared with other diets, combined FO and curcumin feeding enhanced the resolution of chronic inflammation and suppressed (P < 0·05) a key inflammatory mediator, NF-κB, in the colon mucosa. Mucosal microarray analysis revealed that dietary FO, curcumin and FO plus curcumin combination differentially modulated the expression of genes induced by DSS treatment. These results suggest that dietary lipids and curcumin interact to regulate mucosal homeostasis and the resolution of chronic inflammation in the colon.
This paper compares strains of foot-and-mouth disease (FMD) serotype SAT (South African Territories) 2 viruses isolated from Zimbabwe and other African countries using monoclonal antibodies (MAb). A sandwich-ELISA was used to examine the relative binding of anti-SAT 2 MAb to the various viruses. The MAb-binding profiles of viruses isolated from field samples were compared using hierarchical cluster analysis. Viruses were obtained from game animals, mainly African buffalo (Syncerus caffer) which is the natural host and reservoir for SAT serotypes in Africa, and from cattle showing clinical signs of FMD, as well as from animals suspected of carrying the virus subclinically. Some isolates have been adapted for use as vaccine strains. The results showed that most of the Zimbabwe isolates collected between 1989 and 1992 were an antigenically closely-related group. Although differences were observed between Zimbabwe isolates collected between 1989 and 1992 and those collected in 1987, there was no correlation with the different MAb binding patterns within the 1987 group and the epidemiological information received from the field. Similar profiles were observed for many SAT 2 viruses, including viruses isolated over a 50-year period and from geographically distant areas. This indicates an inherent stability in antigenic profiles of SAT 2 viruses. The MAb panel was capable of assessing antigenic variation, since very different profiles were obtained for some isolates. The work also allowed comparison and characterization of anti-type SAT 2 MAb from different laboratories. The findings are discussed with reference to selection of vaccine strains.
Thermodynamic bounds on the magnetic fluctuation energy in unstable anisotropic plasmas are obtained. The spatial variation in equilibrium and perturbed quantities is assumed to be exclusively in the z direction, which coincides with the direction of a uniform external magnetic field B0êz. In addition, the positive ions are assumed to form a fixed (mi→ ∞) background providing overall charge neutrality, and only the electron dynamics are included in the analysis. For this configuration it has recently been shown that the non-linear Vlasov–Maxwell equations support two independent energy constants for arbitrary-amplitude electromagnetic disturbances propagating parallel to B0 êz. In this paper, Fowler's method for calculating thermodynamic bounds on the field energy in unstable plasmas is generalized to incorporate two energy constraints (in addition to entropy and number conservation). An upper bound on the magnetic fluctuation energy is obtained for arbitrary initial distribution function fe0 = fe(z, v, 0), and the results are applied to unstable (i) bi-Maxwellian and (ii) loss-cone distributions. Depending on the parameter regime, it is found that the bounds obtained by enforcing two energy constraints can be an order-of-magnitude lower than the bounds obtained by enforcing a single (total) energy constraint. The theoretical bounds are compa red with the maximum change in field energy measured in computer simulation experiments for the case where fe0 is bi-Maxwellian. For sufficiently large initial anisotropy, it is found that the bound obtained with two energy constraints is less than 1·5 times the measured change in field energy.
The plasma membranes of all eukaryotic cells contain heterogeneous self-organising intrinsically unstable liquid ordered domains or lipid assemblies in which key signal transduction proteins are localised. These assemblies are classified as ‘lipid rafts’ (10–200 nm), which are composed mostly of cholesterol and sphingolipid microdomains and therefore do not integrate well into the fluid phospholipid bilayers. In addition, caveolae represent a subtype of lipid raft macrodomain that form flask-shaped membrane invaginations containing structural proteins, i.e. caveolins. With respect to the diverse biological effects of long-chain PUFA, increasing evidence suggests that n-3 PUFA and perhaps conjugated fatty acids uniquely alter the basic properties of cell membranes. Because of its polyunsaturation, DHA and possibly conjugated linoleic acid are sterically incompatible with sphingolipid and cholesterol and, therefore, appear to alter lipid raft behaviour and protein function. The present review examines the evidence indicating that dietary sources of n-3 PUFA can profoundly alter the biochemical make up of lipid rafts/caveolae microdomains, thereby influencing cell signalling, protein trafficking and cell cytokinetics.
Many of the most pervasive disease challenges to livestock are transmitted via oral contact with faeces (or by faecal–aerosol) and the current paper focuses on how disease risk may depend on: spatial heterogeneity, animal searching behaviour, different grazing systems and faecal deposition patterns including those representative of livestock and a range of wildlife. A spatially explicit agent-based model was developed to describe the impact of empirically observed foraging and avoidance behaviours on the risk of disease presented by investigative and grazing contact with both livestock and wildlife faeces. To highlight the role of spatial heterogeneity on disease risks an analogous deterministic model, which ignores spatial heterogeneity and searching behaviour, was compared with the spatially explicit agent-based model. The models were applied to assess disease risks in temperate grazing systems. The results suggest that spatial heterogeneity is crucial in defining the disease risks to which individuals are exposed even at relatively small scales. Interestingly, however, although sensitive to other aspects of behaviour such as faecal avoidance, it was observed that disease risk is insensitive to search distance for typical domestic livestock restricted to small field plots. In contrast disease risk is highly sensitive to distributions of faecal contamination, in that contacts with highly clumped distributions of wildlife contamination are rare in comparison to those with more dispersed contamination. Finally it is argued that the model is a suitable framework to study the relative inter- and intra-specific disease risks posed to livestock under different realistic management regimes.
Reduction in wildlife populations is a common method for the control of livestock infections which have wildlife hosts, but its success is dependent on the characteristics of the infection itself, as well as on the spatial and social structure of the wildlife host. Paratuberculosis (Mycobacterium avium subsp. paratuberculosis; Map) is a widespread and difficult infection to control in livestock populations and also has possible links to Crohn's disease in humans. Rabbits have recently been identified as a key wildlife species in terms of paratuberculosis persistence in the environment and risk to the wider host community, including cattle. Here we use a spatially explicit stochastic simulation model of Map dynamics in rabbit populations to quantify the effects of rabbit population control on infection persistence. The model parameters were estimated from empirical studies of rabbit population dynamics and rabbit-to-rabbit routes of Map transmission. Three rabbit control strategies were compared: single unrepeated population reductions based on removing individual animals; single unrepeated population reductions based on removal of entire social groups; and repeated annual population reductions based on removing individual animals. Unrealistically high rabbit culls (>95% population reduction) are needed if infection is to be eradicated from local rabbit populations with a single one-off population reduction event, either of individuals or social groups. Repeated annual culls are more effective at reducing the prevalence of infection in rabbit populations and eradicating infection. However, annual population reductions of >40% are required over extended periods of time (many years). Thus, using an approach which is both highly conservative and parsimonious with respect to estimating lower bounds on the time to eradicate the infection, we find that Map is extremely persistent in rabbit populations and requires significant and prolonged effort to achieve control.