Land management shapes drought responses of dominant soil microbial taxa across grasslands.

Soil microbial communities are dominated by a relatively small number of taxa that may play outsized roles in ecosystem functioning, yet little is known about their capacities to resist and recover from climate extremes such as drought, or how environmental context mediates those responses. Here, we imposed an in situ experimental drought across 30 diverse UK grassland sites with contrasting management intensities and found that: (1) the majority of dominant bacterial (85%) and fungal (89%) taxa exhibit resistant or opportunistic drought strategies, possibly contributing to their ubiquity and dominance across sites; and (2) intensive grassland management decreases the proportion of drought-sensitive and non-resilient dominant bacteria-likely via alleviation of nutrient limitation and pH-related stress under fertilisation and liming-but has the opposite impact on dominant fungi. Our results suggest a potential mechanism by which intensive management promotes bacteria over fungi under drought with implications for soil functioning.

Refractive and visual outcomes of surgical treatments for high myopia

Objective@#To present the refractive and visual outcomes of refractive surgical treatment options in high myopia. @*Methods@#This was a retrospective review of patients diagnosed with high myopia (manifest refractive spherical equivalent [MRSE] ≥-6.00D) who underwent one of the following procedures: laser-in-situ keratomileusis (LASIK), photorefractive keratectomy (PRK), phakic IOL implantation with the Staar Implantable Collamer Lens (ICL), or Alcon Cachet Phakic IOL. Eyes with best corrected distance vision of less than 20/30 due to amblyopia or other eye pathologies were excluded.

Consistent patterns and the idiosyncratic effects of biodiversity in marine ecosystems.

Revealing the consequences of species extinctions for ecosystem function has been a chief research goal and has been accompanied by enthusiastic debate. Studies carried out predominantly in terrestrial grassland and soil ecosystems have demonstrated that as the number of species in assembled communities increases, so too do certain ecosystem processes, such as productivity, whereas others such as decomposition can remain unaffected. Diversity can influence aspects of ecosystem function, but questions remain as to how generic the patterns observed are, and whether they are the product of diversity, as such, or of the functional roles and traits that characterize species in ecological systems. Here we demonstrate variable diversity effects for species representative of marine coastal systems at both global and regional scales. We provide evidence for an increase in complementary resource use as diversity increases and show strong evidence for diversity effects in naturally assembled communities at a regional scale. The variability among individual species responses is consistent with a positive but idiosyncratic pattern of ecosystem function with increased diversity.

A microbiologist's view of factors contributing to infection.

Why some patients develop postoperative surgical wound infection and others do not remains a mystery. There are many risk factors for infection, and mathematical scoring systems are often good predictors of infection; yet, some patients with a plethora of risk factors fail to develop surgical site infections. Even patients with established abdominal infection do not automatically develop wound infection. Early experimental work, now confirmed in the clinical setting, dictates that bacteria must be in the wound to cause infection; the minimal infecting dose will depend on the environmental conditions in the wound. The presence of foreign bodies, trauma, hematoma, etc., will enhance the effect of the inoculum; therefore, surgical debridement and careful surgery are necessary to reinforce the host defenses. Some bacteria, e.g., Staphylococcus aureus and Streptococcus pyogenes, have a greater propensity to cause infection, so extensive infection-control practices are necessary to prevent or contain these pathogens. To minimize the risk of surgical site infection, individual patient risk factors must be identified and modified whenever possible. The patient should be prepared for the operation and appropriate skin antiseptics should be used on the operative site. The patient should be considered for perioperative antibiotic prophylaxis and, if appropriate, bowel preparation should be carried out. Care and attention to the theater operating environment is important, especially for cases in which airborne transmission of bacteria should be controlled, e.g., ultraclean air systems for implant surgery. In elective surgery, the source of bacteria that cause infection is either the patient's normal flora (e.g., skin or bowel), i.e., endogenous, or the surgical staff or environment, i.e., exogenous. Surgical expertise and theater discipline are essential components in the fight against surgical sepsis.

Nosocomial staphylococcal outbreaks.

Staphylococcus aureus is the most frequently isolated single bacterial species from surgical wounds. During 1954-59, S. aureus phage 80/81 was responsible for more than 20% of staphylococcal epidemics in British hospitals. With the introduction of methicillin came satisfactory treatment of staphylococcal infection, though strains of methicillin-resistant S. aureus (MRSA) were quickly discovered. Outbreaks of MRSA infection usually start with the transfer or admission of either a patient or healthcare worker colonized or infected with MRSA from another hospital or the community. Long-stay patients act as reservoirs for MRSA which spread via several modes of transmission. Hospital outbreaks of MRSA infection are difficult to control and may require stringent containment measures entailing considerable expense. Infection control is dependent on staff education programmes and surveillance. In the event of an MRSA epidemic, infection control staff may need to solicit the help of a team of trained specialists to implement intensive surveillance programmes, to identify and isolate MRSA carriers and eradicate the carriage of MRSA. Antibiotics are widely used for the prevention of infection, but control should be exercised as excessive antibiotic use has been identified as a risk factor for outbreaks of infection.

Determining and improving the fault tolerance of multilayer perceptrons in a pattern-recognition application.

We investigate empirically the performance under damage conditions of single- and multilayer perceptrons (MLP's), with various numbers of hidden units, in a representative pattern-recognition task. While some degree of graceful degradation was observed, the single-layer perceptron was considerably less fault tolerant than any of the multilayer perceptrons, including one with fewer adjustable weights. Our initial hypothesis that fault tolerance would be significantly improved for multilayer nets with larger numbers of hidden units proved incorrect. Indeed, there appeared to be a liability to having excess hidden units. A simple technique (called augmentation) is described, which was successful in translating excess hidden units into improved fault tolerance. Finally, our results were supported by applying singular value decomposition (SVD) analysis to the MLP's internal representations.

An evaluation of five serological tests for the detection of antibody to bovine herpesvirus 1 in vaccinated and experimentally infected cattle.

More than 300 bovine sera from a previously reported vaccination and challenge trial were tested for antibodies to bovine herpesvirus 1 (BHV1) by five serological assays: enzyme-linked immunosorbent assay (ELISA) for IgM and IgG, passive haemagglutination (PHA), and two methods of virus neutralisation (VN). In a statistical comparison of ELISA (IgG), PHA and VN results, the assays showed highly significant correlations (P less than 0.01). The sensitivities of ELISA and 24-hour neutralisation tests were similar, in contrast to passive haemagglutination and one hour neutralisation which failed to detect BHV1 antibodies in some low titre sera.

Efficacy of porcine parvovirus vaccines.

Three inactivated porcine parvovirus vaccines were tested for efficacy in 66 susceptible gilts. The gilts were challenged with virulent virus on the 40th day of gestation. All the vaccines provided excellent protection against fetal mortality despite insignificant serological responses to one of them. Good protection was obtained with two of the vaccines even when the dose was substantially reduced. Unvaccinated controls had very few viable fetuses.