Simulating nitrogen balance in Canadian agricultural soils from 1981 to 2016.

Agriculture produces food, fiber and biofuels for the world's growing population, however, agriculture can be a major contributor of nitrogen (N) losses including emissions of ammonia (NH3), nitrous oxide (N2O) and nitrate (NO3-) leaching and runoff. A Canadian Agricultural Nitrogen Budget for Reactive N (CANBNr) model was developed to estimate the soil N balance in 3487 soil landscape of Canada polygons from 1981 to 2016. The CANBNr model integrates NH3 emission from fertilizers, manure from housing, storage and field, as well as direct/indirect N2O emissions from fertilizers, manures, crop residues and soil organic matter. The NO3- leaching is estimated based on the residual soil N (RSN) at harvest and drainage derived with the DeNitrification-DeComposition (DNDC) model. From 1981 to 2016, the N input from fertilizer and N fixation increased at a greater rate than N removal in harvested crops in all provinces of Canada, resulting in an increase in the RSN and N losses. In 2016, the Prairie provinces had lower N losses (11.7 kg N ha-1) from N2O, NH3 and NO3- compared with 43.2 kg N ha-1 in central Canada, and 76.5 kg N ha-1 in Atlantic Canada. However, the Prairie provinces had 84.3% of the total Canadian farmland (74.3% of the total Canadian N input), while central Canada had 12.9% of Canadian farmland (21.7% of the total Canadian N input). In the Prairie provinces, the total N2O loss from fertilizer N ranged 4.4-8.6 Gg N whereas NH3 loss ranged from 17.1 to 44.6 Gg N and these values were influenced by both emission intensity and total land area. Total N2O losses from manure were highest in Alberta, Ontario and Quebec resulting in 4.8, 4.4, and 3.4 Gg N and NH3 losses from manure were also highest in these 3 provinces at 61.1, 45.2 and 40.4 Gg N, respectively. Nitrate leaching was impacted by drainage volumes, soil type and N inputs. In the non-growing season, NO3- leaching losses (36-yr average) were 63.3 Gg in Ontario and 57.5 Gg N in Quebec compared with 20.8 Gg N for Ontario and 35.5 Gg N for Quebec in the growing season. In contrast, the Prairie provinces showed higher NO3- leaching in the growing season (23.1-37.4 Gg N) than in the non-growing season (10.4-13.7 Gg N). In summary, total fertilizer N increased the most over the 36 years in the Prairies which resulted in increased RSN and N leaching losses that will require further intervention.

Influence of two management practices in the Canadian Prairies on radiative forcing.

Surface albedo and soil carbon sequestration are influenced by agricultural management practices which impact the Earth's radiation budget and climate change. In this study we investigate the impact of reduced summer fallowing and reduced tillage in the Canadian Prairies on climate change by estimating the change in radiative forcing due to albedo and soil carbon sequestration. Seasonal variations of albedo, which are dependent on agricultural management practices and soil colour in three soil zones, were derived from 10-day composite 250-m Moderate Resolution Imaging Spectroradiometer (MODIS) data. Using this information, we found an overall increase of surface albedo due to the conversion from summer fallowing to continuous cropping and from conventional tillage (CT) to either no-tillage (NT) or reduced tillage (RT). The increase was dependent on soil brightness, type of vegetation and snow cover. Using data from the Census of Agriculture and taking into consideration both albedo and soil carbon changes, we estimated that from 1981 to 2016, the total radiative forcing for the cropland area in the Canadian Prairies was -405 µW m-2 due to the conversion of CT to either NT or RT and about 70% was due to the change in albedo. During the same period, the total radiative forcing was -410 µW m-2 due to a reduction in the area under summer fallow and about 62% was due to the change in albedo. The equivalent atmospheric CO2 drawdown from these two management changes from albedo change was about 7.8 and 8.7 Tg CO2 yr-1, respectively. These results demonstrate that it is important to consider both the changes of soil carbon and surface albedo in evaluating climate change impacts due to agricultural management practices.

Assessing the effects of manure application rate and timing on nitrous oxide emissions from managed grasslands under contrasting climate in Canada.

It is uncertain whether process-based models are currently capable of simulating the complex soil, plant, climate, manure management interactions that influence soil nitrous oxide (N2O) emissions from perennial cropping systems. The objectives of this study were (1) to calibrate and evaluate the DeNitrification DeComposition (DNDC) model using multi-year datasets of measured nitrous oxide (N2O) fluxes, soil moisture, soil inorganic nitrogen, biomass and soil temperature from managed grasslands applied with manure slurry in contrasting climates of Canada, and (2) to simulate the impact of different manure management practices on N2O emissions including slurry application i) rates (for both single vs. split); and ii) timing (e.g., early vs. late spring). DNDC showed "fair" to "excellent" performance in simulating biomass (4.7% ≤ normalized root mean square error (NRMSE) ≤ 29.8%; -9.5% ≤ normalized average relative error (NARE) ≤ 16.1%) and "good" performance in simulating soil temperature (13.2% ≤ NRMSE ≤ 18.1%; -0.7% ≤ NARE ≤ 10.8%) across all treatments and sites. However, the model only showed "acceptable" performances in estimating soil water and inorganic N contents which was partially attributed to the limitation of a cascade water sub-model and inaccuracies in simulating root development/uptake. Although, the DNDC model only demonstrated "fair" performance in simulating daily N2O fluxes, it generally captured the impact of the timing and rate of slurry application and soil texture (loam vs. sandy loam) on total N2O emissions. The DNDC model simulated N2O emissions from spring better than split manure application (fall and spring) at the Manitoba site partially due to the overestimation of available substrates for microbial denitrification from fall application during the wet spring periods. Although DNDC performed adequately for simulating most of the manure management impacts considered in this study we recommend improvements in the simulation of soil freeze-thaw cycles, manure decomposition dynamics, soil water storage, rainfall canopy interception, and microbial denitrification and nitrification activities in grasslands.

Parenting and female dermatologists' perceptions of work-life balance.

BACKGROUND: Women in medicine may feel pressure to choose between the competing demands of career goals and being a dedicated spouse and parent. OBJECTIVE: The purpose of this survey study is to report on the current opinions of female dermatologists with regard to family planning, maternity leave, and career success. METHODS: We surveyed 183 members of the Women's Dermatologic Society using a 13-question survey that was approved for distribution by the institutional review board committee of the University of Connecticut Health Center. RESULTS: We found that women were most likely to have children while they were residents (51%), despite the fact that residents were more likely to report barriers to childbearing at this career stage. These barriers included length of maternity leave, appearing less committed to residency responsibilities compared with peers, and inadequate time and privacy to breast feed. Strategies to achieve a work-life balance included hiring in-home help and working part-time. Of note, many women commented on the need for more family planning resources at work. CONCLUSION: Thought should be given to future administrative strategies that can lessen the burden of parents who are dermatologists and have academic ambitions.

Differences in dermatology training abroad: A comparative analysis of dermatology training in the United States and in India.

Dermatology residency training is not standardized internationally, and each country dictates how training is conducted within its own borders. This article highlights the types of variability in training that can occur from country to country by comparing dermatology residency training programs in the United States and India. This article specifically analyzes the differences that pertain to application and selection, residency program structure, and post-residency opportunities.

The drebrin/EB3 pathway drives invasive activity in prostate cancer.

Prostate cancer is the most common cancer in men and the metastatic form of the disease is incurable. We show here that the drebrin/EB3 pathway, which co-ordinates dynamic microtubule/actin filament interactions underlying cell shape changes in response to guidance cues, plays a role in prostate cancer cell invasion. Drebrin expression is restricted to basal epithelial cells in benign human prostate but is upregulated in luminal epithelial cells in foci of prostatic malignancy. Drebrin is also upregulated in human prostate cancer cell lines and co-localizes with actin filaments and dynamic microtubules in filopodia of pseudopods of invading cells under a chemotactic gradient of the chemokine CXCL12. Disruption of the drebrin/EB3 pathway using BTP2, a small molecule inhibitor of drebrin binding to actin filaments, reduced the invasion of prostate cancer cell lines in 3D in vitro assays. Furthermore, gain- or loss-of-function of drebrin or EB3 by over-expression or siRNA-mediated knockdown increases or decreases invasion of prostate cancer cell lines in 3D in vitro assays, respectively. Finally, expression of a dominant-negative construct that competes with EB3 binding to drebrin, also inhibited invasion of prostate cancer cell lines in 3D in vitro assays. Our findings show that co-ordination of dynamic microtubules and actin filaments by the drebrin/EB3 pathway drives prostate cancer cell invasion and is therefore implicated in disease progression.

Dermatologic diseases of the breast and nipple.

Breast and nipple skin is commonly affected by various inflammatory and neoplastic processes. Despite this fact, many physicians are unaware of the spectrum of diseases that can involve this area. Because breast and nipple skin represents a cosmetically, sexually, and functionally important entity to most patients, awareness of these disease entities is invaluable. This article reviews the normal anatomy of the breast, cutaneous manifestations of neoplastic processes that can present in these areas, and common inflammatory diseases of the breast and nipple skin.

Urinary excretion profiles of 11-nor-9-carboxy-delta9-tetrahydrocannabinol: a delta9-THCCOOH to creatinine ratio study.

Monitoring the major cannabinoid metabolite (delta9-THCCOOH) to creatinine ratio (M/C) has been used to predict new drug use. According to Huestis and Cone, the best accuracy (85.4%) for predicting new marijuana use was a ratio > or = 0.5 from two urine specimens collected at least 24 h apart. Manno et al. recommended an M/C ratio of > or = 1.5. Subjects with a history of chronic marijuana use were screened for cannabinoid use by immunoassay (50-ng/mL cutoff), and presumptive positives were confirmed by gas chromatography-mass spectrometry for delta9-THCCOOH (15-ng/mL cutoff). Creatinine was analyzed with a cutoff concentration of 25 mg/dL. The study objective was to apply the criteria from both groups of workers to determine if consecutive urine specimens (collected at least 24 h apart) positive for cannabinoids could be used to differentiate new marijuana use from the excretion of residual cannabinoid metabolite (delta9-THCCOOH) in an uncontrolled setting. Serial urine specimens (826) were collected from 26 individuals. Huestis and Cone and Manno et al. ratios indicated new drug use in 83% and 33% of serial urine specimens collected at least 24 h apart, respectively. Clinically, the Huestis and Cone ratio is recommended because of a lower false-negative rate (7.4%) than the Manno et al. false-negative rate (24%). In legal situations, we recommend using the Manno et al. ratio because of its lower false-positive rate (0.1%) as stated by Huestis and Cone.

Experience with a urine opiate screening and confirmation cutoff of 2000 ng/mL.

Until recently, most laboratories used an opiate immunoassay screening and confirmation cutoff value of 300 ng/mL for codeine and morphine detection by gas chromatography-mass spectrometry (GC-MS). The cutoff value for opiates was increased to 2000 ng/mL or higher in various laboratories because of concerns that small doses of codeine and foods containing poppy seeds would give a positive opiate-screening result. Workplace drug-testing programs in the U.S. raised the opiate cutoff value to 2000 ng/mL on 30 November 1998. The objective of this study is to describe the results of opiate testing of 8600 urine specimens collected over 24 months with a 2000-ng/mL screening and confirmation (codeine and morphine) cutoff value. Specimens were screened by the EMITdau opiate assay using an in-house 2000-ng/mL morphine calibrator. Presumptive positive findings (N = 621) were analyzed quantitatively by GC-MS for codeine and morphine. One hundred and eighty six urine specimens were positive for codeine and morphine (> 2000 ng/mL), 298 specimens were positive for codeine only (> 2000 ng/mL) and 26 specimens were positive for morphine only (> 2000 ng/mL). All remaining specimens had codeine and morphine values < 2000 ng/mL. The codeine and morphine confirmation rate in this program reduced from 7.1% in 1994-1996 (300-ng/mL cutoff) to 2.1% in 1997-1998 with a 2000-ng/mL cutoff value. The codeine-only confirmation rate lowered from 6.6% (300-ng/mL cutoff) to 3.4% (2000-ng/mL cutoff). It was concluded that increasing opiate screening and codeine and morphine confirmation cutoff values led to > 300% reduction in the confirmed-positive rate for codeine and morphine and a 47% reduction in codeine-only confirmations in a urine drug-testing program where codeine was the major opiate used.

Mucocutaneous reactions to chemotherapy.

UNLABELLED: Chemotherapeutic agents are a widely used treatment modality. Side effects range from common to unusual and may be confused with other cutaneous sequelae of oncologic treatment. The goal of this communication is to elaborate on previous descriptions of the cutaneous manifestations of chemotherapeutic treatment and to discuss more recent findings. LEARNING OBJECTIVE: At the conclusion of this learning activity, participants should be able to generate a differential diagnosis of possible etiologies for varying patterns of cutaneous involvement in patients receiving chemotherapy and identify the various cutaneous side effects of chemotherapeutic treatment. In addition, they should be able to distinguish life-threatening side effects that require immediate management from more benign manifestations of chemotherapeutic treatment.

Variation amongst human isolates of Brachyspira (Serpulina) pilosicoli based on biochemical characterization and 16S rRNA gene sequencing.

Brachyspira pilosicoli (formerly Serpulina pilosicoli) causes swine spirochaetosis and can also be isolated fro human faeces, although its role in human disease remains unclear. The genetic and biochemical variations amongst 19 isolates of human spirochaetes from five different countries were evaluated and compared to those found amongst swine isolates of B. pilosicoli. All isolates were negative for beta-glucosidase and all but one were positive for hippurate hydrolysis, which are characteristics typical of B. pilosicoli. The isolates showed variation in indole production and alpha-galactosidase and alpha-glucosidase activity, other characteristics which can be used to identify B. pilosicoli. The DNA sequences of part of the 16S rRNA gene differed from each other and from that of B. pilosicoli by 0-3 bp out of 283 bp. It is concluded that there is considerable variation amongst human intestinal spirochaetes. Since few of the isolates reported here match the current criteria for B. pilosicoli, it is concluded that this species is more heterogeneous than previously appreciated. However, it cannot be excluded that some isolates may belong to uncharacterized related Brachyspira/Serpulina species.

Quinolone antibacterials: preparation and activity of bridged bicyclic analogues of the C7-piperazine.

A series of quinolone and naphthyridine antibacterial agents possessing as the C7-heterocycle bicyclic 2,5-diazabicyclo[n.2.m]alkanes, where n = 2, 3 and m = 1, 2, and a series including 4-aminopiperidine and 3-amino-8-azabicyclo[3.2.1]octanes have been prepared and evaluated in vitro and in vivo for antibacterial activity against a variety of Gram-negative and Gram-positive organisms. These compounds were also tested against the target enzyme bacterial DNA gyrase. All the examples investigated are nearly equipotent with the parent 7-piperazinyl analogues. Only endo-7-(3-amino-8-azabicyclo[3.2.1]oct-8-yl)-1-cyclopropyl-6,8-difluoro- 1,4- dihydro-4-oxo-3-quinolinecarboxylic acid displays activity that surpasses that of the piperazine parent.

Instantaneous axes of rotation of the typical cervical motion segments: a study in normal volunteers.

The locations of the instantaneous axes of rotation for the cervical motion segments C2-3 to C6-7 were determined from flexion-extension radiographs of 40 normal subjects using a modified overlay technique. The biological variation of the instantaneous axes of rotation was small, as was the technical error associated with the technique used. The data obtained enabled the formal definition of the normal range of locations for the instantaneous axes of rotation of the typical cervical motion segments.

Instantaneous axes of rotation of the typical cervical motion segments: I. an empirical study of technical errors.

The reliability of the conventional technique for determining the instantaneous axes of rotation of the cervical motion segments was evaluated by comparing the determinations made by two observers and the same observer on two separate occasions. Different observers found the same mean location for the instantaneous axis at each segment in a test population of 17 normal subjects, but for any given subject the interobserver and intraobserver differences were large, with a relative variation of up to 35%. Thus, while reliable for determining the mean location of the instantaneous axis of rotation in a population, the technique was not reliable for determining the axis in a given subject. Qualitative analysis suggested that the identification of the radiographic images of the vertebrae and their tracing is the greatest source of error for this technique.