To save 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 saving content to .
To save 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 saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved 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.
Escherichia coli concentration levels in recreational water are used by beach managers to evaluate the risk of gastrointestinal illness among beachgoers. We examined the relationship between specific environmental factors and E. coli concentration in recreational beaches in the Niagara Region. We analysed E. coli geometric means collected from eight beaches from two of the Great Lakes in the Niagara Region in Ontario, between 2011 and 2019. We applied path analysis to evaluate the relationship between the environmental factors and E. coli concentrations, including whether effects were direct or indirect via a mediator. Turbidity was found to be an important mediator for the indirect effect of environmental variables overall and in beach-specific models. Rainfall and streamflow had a positive indirect effect on E. coli via turbidity and a direct effect in five out of seven beach models. Streamflow was also a mediator for the indirect effect of previous day air temperature in five out of seven models. In three subset models, outfall E. coli concentration was a mediator for the effect of the environmental factors. Using a novel methodological approach, this study identifies important relationships and pathways that predict beach E. coli concentration in freshwater beaches located on two of the Great Lakes.
To detail the activities of the Veterans Health Administration (VHA) Antimicrobial Stewardship Initiative and evaluate outcomes of the program.
The VHA is a large integrated healthcare system serving approximately 6 million individuals annually at more than 140 medical facilities.
Utilization of nationally developed resources, proportional distribution of antibiotics, changes in stewardship practices and patient safety measures were reported. In addition, inpatient antimicrobial use was evaluated before and after implementation of national stewardship activities.
Nationally developed stewardship resources were well utilized, and many stewardship practices significantly increased, including development of written stewardship policies at 92% of facilities by 2015 (P<.05). While the proportional distribution of antibiotics did not change, inpatient antibiotic use significantly decreased after VHA Antimicrobial Stewardship Initiative activities began (P<.0001). A 12% decrease in antibiotic use was noted overall. The VHA has also noted significantly declining use of antimicrobials prescribed for resistant Gram-negative organisms, including carbapenems, as well as declining hospital readmission and mortality rates. Concurrently, the VHA reported decreasing rates of Clostridium difficile infection.
The VHA National Antimicrobial Stewardship Initiative includes continuing education, disease-specific guidelines, and development of example policies in addition to other highly utilized resources. While no specific ideal level of antimicrobial utilization has been established, the VHA has shown that improving antimicrobial usage in a large healthcare system may be achieved through national guidance and resources with local implementation of antimicrobial stewardship programs.
A literature-based compilation of phylogenetic relationships and biometric measurements of 342 Cenozoic planktonic foraminiferal species suggests that the group shows a net increase in size through the Cenozoic, thus appearing to follow Cope's Rule of phyletic size increase. However, when the data are corrected for size-related biases, they do not support the hypothesis that this apparent trend is driven by an organismal adaptive advantage of larger size.
When the planktonic foraminifera return to their “primitive” globigerine morphology during the Eocene-Oligocene transition, there is no indication of size-dependent origination or extinction; however, when the extinction signal is decomposed into pseudoextinctions and true lineage terminations, a differential pulse of pseudoextinction is observed among the smaller forms. This observation suggests that smaller bodied species, rather than surviving stressful times with static morphologies, may evolve their way through times of crisis and go on to found lineages which, by virtue of their initial small size, are stochastically likely to increase in mean size during subsequent diversification. Thus, one general explanation for Cope's Rule might be that smaller bodied species are more adaptively responsive due to their tendency to have shorter generation times. During times of stress, this adaptive responsiveness may give them an advantage that is correlated with, but causally unrelated to, their size.
The evolutionary origin of Morozovella angulata from its immediate ancestor, Praemurica uncinata, is preserved in Paleocene sediments from the Gulf of Mexico. This event represents the beginning of the morozovellid radiation and marks the first appearance of keeled planktonic foraminifera after the Cretaceous/Tertiary extinction. Parallel biometric and isotopic analyses were performed on size-segregated specimens from a succession of stratigraphic horizons. The biometric data reveal a temporal pattern of variation consistent with paedomorphosis. The appearance of angulose juvenile chambers in the otherwise rounded ancestral form (Praemurica uncinata) results in an allometry that becomes more pronounced upsection. At the origin of M. angulata, the juvenile morphology of the ancestor is retained throughout the entire ontogeny. Isotopic analysis of this sequence reveals the gradual acquisition of an increasingly heavy adult δ13C signal relative to that of the juvenile, while the δ18O data display no temporal or size-related trends. The temporal increase seen in the slope of the δ13C/size relationship may reflect the evolution of an increased dependency on photosymbionts.
In the early 1950s, Lancefield divided streptococci into groups based on carbohydrates present in the cell wall and designated the groups A through H and K through T. In addition, streptococci may be classified by their characteristics on culture on sheep blood agar. β-Hemolytic streptococci produce zones of clear hemolysis around each colony; α-hemolytic streptococci (Streptococcus viridans) produce a green discoloration characteristic of incomplete hemolysis; absence of hemolysis is characteristic of γ-streptococci.
The sole member of Lancefield group A is Streptococcus pyogenes. Group A streptococcus is ubiquitous in the environment but with rare exceptions is exclusively found in or on the human host. About 5% to 20% of the population harbor group A streptococcus in their pharynx, and some are colonized on their skin. This organism produces a variety of suppurative infections; however, streptococcal pharyngitis, the most common, is characterized by the onset of sore throat, fever, painful swallowing, and chilliness. These symptoms combined with submandibular adenopathy, pharyngeal erythema, and exudates correlate with positive throat cultures in 85% to 90% of cases. Sore throat without fever or any of the other signs and symptoms has a low predictive value for pharyngitis caused by group A streptococcus. Rapid strep tests correlate with positive cultures in 68% to 99% of cases, but results depend greatly on the individual performing the test as well as the bacterial colony count. Colony counts greater than 100 per plate correlated with positive rapid strep tests in 95% of patients, and counts less than 100 per plate correlated with positive rapid strep tests for only 68% of patients.
In the early 1950s, Lancefield divided streptococci into groups based on carbohydrates present in the cell wall and designated the groups A through H and K through T. In addition, streptococci may be classified by their characteristics on culture on sheep blood agar. β-Hemolytic streptococci produce zones of clear hemolysis around each colony; α-hemolytic streptococci (Strepococcus viridans) produce a green discoloration characteristic of incomplete hemolysis; absence of hemolysis is characteristic of γ-streptococci.
The sole member of Lancefield group A is Streptococcus pyogenes. Group A streptococcus is ubiquitous in the environment but with rare exceptions is exclusively found in or on the human host. About 5% to 20% of the population harbor group A streptococcus in their pharynx, and some are colonized on their skin. This organism produces a variety of suppurative infections; however, streptococcal pharyngitis, the most common, is characterized by the onset of sore throat, fever, painful swallowing, and chilliness. These symptoms combined with submandibular adenopathy, pharyngeal erythema, and exudates correlate with positive throat cultures in 85% to 90% of cases. Sore throat without fever or any of the other signs and symptoms has a low predictive value for pharyngitis caused by group A streptococcus. Rapid strep tests correlate with positive cultures in 68% to 99% of cases, but results depend greatly on the individual performing the test as well as the bacterial colony count.
Background. There has been ethical concern that participants in psychiatric research will become distressed and their mental state might worsen.
Method. A systematic search was carried out for studies that examined distress following participation in research that involved the assessment of psychiatric state or associated risk factors. There were 46 relevant studies.
Results. A minority of participants become distressed immediately after participation, with distress more likely in studies of traumatic experiences. There is limited evidence on longer-term effects, but what there is suggests no adverse impact. Positive reactions to participation show little association with distress and these are more common than negative reactions. Very few studies of distress in research have used control groups to establish causal associations. However, what evidence there is suggests no causal role, including for research on suicidality. Researchers in this area have made a range of suggestions about ethical practice.
Conclusions. A minority of participants in psychiatric research become distressed, but there is no evidence of longer-term harm. Nevertheless, researchers need to take account of ethical concerns in designing studies. Future research in the area needs to be carried out with stronger designs involving control groups.
Data are presented on the demography and reproductive success of cheetahs (Acinonyx jubatus) living on the Serengeti Plains, Tanzania over a 25-year period. Average age at independence was 17.1 months, females gave birth to their first litter at approximately 2.4 years old, interbirth interval was 20.1 months, and average litter size at independence was 2.1 cubs. Females who survived to independence lived on average 6.2 years while minimum male average longevity was 2.8 years for those born in the study area and 5.3 years for immigrants, with a large proportion of males dispersing out of the Plains population. Females produced on average only 1.7 cubs to independence in their entire lifetime and their average reproductive rates were 0.36 cubs per year or 0.17 litters per year to independence. Variance in lifetime reproductive success in the cheetah is similar to that of other mammals.
No significant negative correlations were found between adult cheetah population size and numbers of cubs reaching independence, implying that the Plains population had not reached carrying capacity. Annual numbers of adult female cheetahs only were correlated with rainfall. Adult female cheetah numbers were not correlated with adult female lion numbers on the Plains, however, reproductive rates of cheetahs were negatively correlated with the presence of lions while cheetahs had cubs. Moreover, cheetah reproductive success was lower during the period of high lion abundance (1980-1994) than during the earlier period of relatively few lions (1969-1979). Litter size at independence dropped from 2.5 to 2.0, lifetime reproductive success declined from 2.1 to 1.6 cubs reared to independence, and the reproductive rate (cubs/year) decreased from 0.42 to 0.36 from the earlier to the later period.
Cheetah reproductive success showed little association with the presence of Thomson's gazelle at sightings except for a negative correlation between large numbers of gazelle (200±500) and reproductive success possibly because hunting success decreases with increasing prey herd size, or because cheetahs always lose in direct competition with other predators which are attracted to large congregations of prey. In addition, cheetah reproductive success was negatively correlated with the presence of Grant's gazelles (11 or more) perhaps because Grant's gazelles were more likely to occur consistently in dry areas.
To date, most macroevolutionary studies have focused on taxonomic data; there are very few data sets that provide a large enough statistical population for extensive macroevolutionary studies involving direct morphometric data. The Cenozoic planktonic foraminifera are exceptional in this regard. Digitally captured shape descriptions of 342 species of Cenozoic planktonic foraminifera have been combined with the available data on their phylogenetic relationships to examine the interplay between speciation rates, size change, and various geometric characters. The results tend, at least for the planktonic foraminifera, to support Stanley's (1973) hypothesis regarding the causal mechanisms behind Cope's Rule. The tendency toward size increase may result from the disadvantages of large size during times of mass extinction rather than from the (conventionally assumed) advantages of larger size.
Additional results derived from morphotypic longevities and morphotypic turnover rates suggest an enhanced probability of speciation early in the Cenozoic, and enhanced longevity in the later Cenozoic.
Microevolutionary studies of patterns of changing variance within the Paleocene and Eocene genus Morozovella suggest that conventional foraminiferal taxonomic practice may not accurately reflect biological realities within the group, thus implying that our macroevolutionary results might be interpreted in other ways.
Paedomorphosis has now been seen in several foraminiferal lineages, including Morozovella angulata, a focus of the present study. Isotopic data (Shackleton, Corfield, and Hall, 1985) suggests that evolution of this group is accompanied by the invasion of a stratified water column. These observations suggest that one might look for systematic macroevolutionary morphologic tendencies in chamber expansion rate and size as a guide to understanding paleoecological conditions. It also seems reasonable to suggest that the complex morphological changes seen in the morozovellids may not represent morphological adaptation, but resource-related heterochronic shifts with ancillary morphological consequences.
In this paper we characterize the thin film formed by rapid thermal anneal of a magnetron sputtered titanium film in a nitrogen atmosphere. The barrier properties of this material have been characterized for both n- and p-type junctions in our CMOS technology. We have characterized the physical properties of the film using Auger, RBS and TEM analysis in the same range of temperatures, and find that as the annealing temperature is increased a better quality TiNxOy film is formed. The electromigration characteristics for Aℓ/TiNxOy/TiSi2 runners, as well as the role that this system plays in minimizing failures due to stress induced voiding are examined in this study.
Email your librarian or administrator to recommend adding this to your organisation's collection.