Nitrous Oxide Emissions from a Fertilized and Grazed Grassland in the South East of Ireland

Agriculture currently accounts for 28% of national greenhouse gas emissions in Ireland. Nitrous oxide (N₂O) emissions from agricultural soils account for 38% of this total. A 2-year study was conducted, using the chamber technique on a fertilized and grazed grassland to quantify the effect of fertilizer application rate, soil and meteorological variables on N₂O emissions. Three N fertilizer regimes (0, 225 & 390 kg N ha⁻¹) were imposed with three replicates of each treatment. Nitrogen fertilizer was applied as urea (46% N) in spring with calcium ammonium nitrate (CAN-26% N) applied in the summer (June–September). Rotational grazing was practiced using steers. Nitrous oxide emissions arising from the unfertilized plots (0 N) were consistently low. Emissions from the N-fertilized plots (225 & 390 kg N ha⁻¹) were concentrated in relatively short periods (1–2 weeks) following fertilizer applications and grazing, with marked differences between treatments, relative patterns and magnitudes of emissions at different times of the year and between years. Variation in N₂O emissions throughout both years was pronounced with mean coefficients of variation of 116% in year 1 and 101% in year 2. The study encompassed two climatologically contrasting years. As a result the N₂O–N loss, as a percent of the N applied in the cooler and wetter 2002 (0.2–2.0%), were similar to those used for N-fertilized grasslands under the Intergovernmental Panel on Climate Change (IPCC) N₂O emission inventory calculation methodology (1.25% ± 1). In contrast, the percentage losses in the warmer and drier 2003 (3.5–7.2%) were substantially higher.     

Preventing Substance Abuse in American Indian and Alaska Native Youth: Promising Strategies for Healthier Communities.

Substance abuse has had profoundly devastating effects on the health and well-being of American Indians and Alaska Natives. A wide variety of intervention methods has been used to prevent or stem the development of alcohol and drug problems in Indian youth, but there is little empirical research evaluating these efforts. This article is an overview of the published literature on substance use prevention among Indian adolescents, providing background epidemiological information, a review of programs developed specifically for Indian adolescents, and recommendations for the most promising prevention strategies currently in practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrated hollow waveguides with arch-shaped cores

An optical waveguide is described that has a hollow arch-shaped core. Optical confinement for this structure is based on the antiresonant reflecting optical waveguide principle. The waveguides are built on a silicon substrate using a sacrificial etch technique with reflowed photoresist serving as the sacrificial material and producing the core's arch shape. Investigations of fabrication parameters are reported that allow for predicting a final arch-shaped geometry based on initial photoresist width and thickness. Optical mode guiding is demonstrated in an arch-shaped waveguide with a liquid core.     

Maltose-binding protein interacts simultaneously and asymmetrically with both subunits of the Tar chemoreceptor

The Tar chemotactic signal transducer of Escherichia coli mediates attractant responses to L-aspartate and to maltose. Aspartate binds across the subunit interface of the periplasmic receptor domain of a Tar homodimer. Maltose, in contrast, first binds to the periplasmic maltose-binding protein (MBP), which in its ligand-stabilized closed form then interacts with Tar. Intragenic complementation was used to determine the MBP-binding site on the Tar dimer. Mutations causing certain substitutions at residues Tyr-143, Asn-145, Gly-147, Tyr-149, and Phe-150 of Tar lead to severe defects in maltose chemotaxis, as do certain mutations affecting residues Arg-73, Met-76, Asp-77, and Ser-83. These two sets of mutations defined two complementation groups when the defective proteins were co-expressed at equal levels from compatible plasmids. We conclude that MBP contacts both subunits of the Tar dimer simultaneously and asymmetrically. Mutations affecting Met-75 could not be complemented, suggesting that this residue is important for association of MBP with each subunit of the Tar dimer. When the residues involved in interaction with MBP were mapped onto the crystal structure of the Tar periplasmic domain, they localized to a groove at the membrane-distal apex of the domain and also extended onto one shoulder of the apical region.     

Diagnostic criteria for degenerative, inflammatory, proliferative nonneoplastic and neoplastic liver lesions in medaka (Oryzias latipes): consensus of a National Toxicology Program Pathology Working Group

Women residing in villages in three districts of Pakistan were recruited, trained to deliver primary care and mobilize their communities for health, assigned to limited catchment areas, provided with supervisory and managerial support, and remunerated. Their comprehensive activities substantially reduced infant, child and maternal mortality within a year and generated positive perceptions of family planning in the communities. The programme was cost-effective and appeared suitable as a model for reforming the organization and provision of health care services.     

Variations in the frequency sensitivity of waveguide horns

Rectangular horns have extra parameters, when our only requirement is to design to a particular gain. We can use these to improve the design in various ways. The author has designed horns with a maximally flat frequency response. To achieve this goal, it is necessary to consider the slope of the phase-error loss. When the sum of the phase-error slopes in the E plane and H planes of the rectangular-aperture horn equals 6 dB/octave, the antenna-gain response is flat. The rate of change of phase-error loss equals the 6 dB/octave rate of increase with frequency of an aperture antenna. The article goes beyond the maximally flat frequency response to help the designer find parameters for any reasonable frequency-response gain slope     

The pharmacology of local anesthetics

As practitioners of dentistry we are truly fortunate to have these wonder agents which we tend to use like water everyday. It is estimated that over 11,000,000 cartridges of local anesthetics are administered every year in Ontario. The incredible safety record speaks for itself. However, we must caution ourselves that a local anesthetic is a drug and as such demands our ongoing skill, care and judgment for each individual case.     

The effect of age-dependent increase in fat mass on peripheral insulin action is saturable

Insulin resistance and increased fat mass (FM) are common in human aging. We aimed to investigate the relationship between the age-dependent increase in FM and insulin resistance (by euglycemic hyperinsulinemic clamp technique), in a homogenous rodent model. The decline in insulin responsiveness was linear until late adulthood when body weight, FM, and epididymal fat reached a critical amount (r > .750, for all). Above this critical point, there was no further decline in insulin responsiveness with aging and with increased BW (p < .00001 for all spline curve analyses). This decline in insulin-mediated glucose uptake was accounted for by a decrease in whole body glycolytic rate with no change in the rate of glycogen synthesis. Thus, in this homogenous model, an early increase in FM is associated with impairment in insulin action until a critical FM is achieved, after which there is no additional insulin resistance with aging. We suggest that decreasing insulin responsiveness, in a heterogeneous group such as humans, will only occur within a specific accretion of visceral or total FM.     

CD4 cell counts of 200 x 10(6)/1 or below in natural history studies and surveillance: is one enough or are two better?

A retrospective cohort study was performed to examine the extent and clinical significance of misclassification associated with using the current United States AIDS case defining category of an initial CD4 count < or = 200 cells x 10(6)/l (< or = 200) compared with a definition requiring two consecutive counts below this level. The main outcomes examined were the probability of subsequent CD4 counts > 200 x 10(6)/l (> 200) and progression times to AIDS and death. Of the 2025 predominantly male homosexual HIV-positive patients attending two hospital based HIV clinics with initial CD4 cell counts < or = 200, 1524 (75%) subsequently had consecutive counts < or = 200, but only half did so at the next CD4 count. Ten per cent had either no further or only non-consecutive counts < or = 200, and 15% had only one CD4 count available for analysis. The cumulative proportion of patients with a CD4 count > 200 at one year after a first count of < or = 200 was about twice (39%) that observed among the subgroup with at least two consecutive counts < or = 200 (19%). The times from the initial counts of < or = 200 to AIDS and death were also shorter by six months and two months, respectively, in the subgroup with two or more consecutive counts < or = 200. A significant proportion of patients will be prematurely classified as having a CD4 cell count < or = 200 if a single CD4 count below this level is accepted. A definition of two consecutive counts < or = 200 should be adopted in preference to a single count < or = 200 for natural history studies and clinical trials, in which precise estimates of the time to or from a defined CD4 threshold are important. In surveillance programmes, however, such an approach may be impractical because of missing or infrequent serial CD4 counts, although adjustments can be made based on these estimates of premature misclassification.     

Insulin-dependent diabetes mellitus presenting with ketoalkalosis in Rett syndrome

A 9-year-old girl with Rett syndrome presented with typical symptoms of insulin-dependent diabetes mellitus. Upon investigation she was found to have a primary respiratory alkalosis associated with diabetes ketoacidaemia. Once non-ketotic normoglycaemia was achieved her respiratory alkalosis persisted. This was felt to be due to an abnormal breathing pattern of hyperventilation punctuated by apnoeas which is associated with Rett syndrome.