Long-term Prescribed Fire Does Not Alter Litter Decomposition and Bioavailable Nitrogen in Xeric Oak Forests

The Cross Timbers is a patchwork of grassland, savanna, and xeric oak forest that stretch across Kansas, Oklahoma, and Texas. Historically a pyric ecosystem, burning of the Cross Timbers became infrequent. Currently, land managers are increasingly using prescribed fire as a tool to increase biodiversity, reduce woody encroachment, and decrease wildfire risk. Understanding the effects fire has on litter decomposition is important due to its impacts on carbon storage, nutrient cycling, and erosion. Nitrogen volatilizes in fire and this can reduce the bioavailable nitrogen that, in turn, lowers litter quality. Previous studies have shown that lower litter quality can slow decomposition. Fire can also affect decomposition environment, resulting in altered microbial communities, arthropods, litter depth, moisture, and temperature in the litter layer that can change the rate of decomposition. The objective of our study was to determine whether fire frequency effects on litter quality and decomposition environment alter the rate of decomposition. Litterbags were installed at three wildlife management areas in Oklahoma that have been periodically burned for at least 24 years. Litterbags were collected every three months for a period of 15 months. Major findings of our study were decomposition environment did not affect the rate of decomposition under a closed canopy with fire frequency between 0 and 4.6 fires per decade, and differences observed in litter quality decomposition rates were not due to fire, but some other unexplored mechanism.Forest Resource

Benefits of using liquid sources of potassium fertilizer in northern highbush blueberry

Fertigation with N increases growth and production relative to granular N applications in northern highbush blueberry (Vaccinium corymbosum L.), but little information is available on whether there is any benefit to fertigating with other nutrients. The objective of this study was to evaluate the use of K for fertigation. An initial study was done in a greenhouse to identify appropriate combinations of liquid N and K sources for fertigation using potted plants of ‘Duke’ blueberry. The results indicated that the concentration of K in the soil solution increased by 25% with potassium sulfate (K2SO4) and by 39% with potassium thiosulfate (KTS) and, depending on the soil type, was highest when KTS was applied with urea or ammonium sulfate. Leaf K was affected by K as well as N fertilizers and, on average, was greater with than without K in both an optimum and high pH soil and with KTS than with K2SO4 in the latter soil. A second study was conducted to compare fertigation to granular application of K fertilizer using a mature planting of ‘Duke’ blueberry. Treatments included fertigation (once a week from April to August) with water-soluble K2SO4 or KTS, a single application (April) of granular K2SO4, and no K fertilizer. Each K fertilizer was applied at a total rate of 84 kg/ha K2O per year. After 2 years, the treatments have had no effect on yield or fruit quality. However, fertigation with K2SO4 or KTS resulted in lower pH and higher concentrations of K, Ca, Mg, and S in soil solution under the drip emitters than either no K or granular K2SO4, while granular K2SO4 resulted in higher concentration of K than any other treatment at 15 cm from the drip emitter (edge of the wetting front). The fertigated treatments also had greener leaves (based on SPAD meter readings), greater whole-plant leaf K concentrations, and nearly twice as much extractable K in the soil as the non-fertigated treatments. Additional measurements are underway to determine whether K fertigation will have any effect on yield or fruit quality over the long term

Top Quark Physics at the Tevatron

The discovery of the top quark in 1995, by the CDF and D0 collaborations at the Fermilab Tevatron, marked the dawn of a new era in particle physics. Since then, enormous efforts have been made to study the properties of this remarkable particle, especially its mass and production cross section. In this article, we review the status of top quark physics as studied by the two collaborations using the p-pbar collider data at sqrt(s) = 1.8 TeV. The combined measurement of the top quark mass, m_t = 173.8 +- 5.0 GeV/c^2, makes it known to a fractional precision better than any other quark mass. The production cross sections are measured as sigma (t-tbar) = 7.6 -1.5 +1.8 pb by CDF and sigma (t-tbar) = 5.5 +- 1.8 pb by D0. Further investigations of t-tbar decays and future prospects are briefly discussed.Comment: 119 pages, 59 figures, 17 tables Submitted to Int. J. Mod. Phys. A Fixed some minor error

Weather-based Scheduling and Pulse Drip Irrigation Increase Growth and Production of Northern Highbush Blueberry

Northern highbush blueberry (Vaccinium corymbosum L.) often requires frequent irrigation for commercial production, but irrigation is becoming increasingly challenging for many growers because of warmer and drier weather conditions, increased water regulations, and other water-use limitations. The purpose of this study was to develop improved methods of irrigation to prepare the industry more effectively against future water uncertainties. Treatments were applied for 2 years (2021 and 2022) and included a combination of weather-based or fixed irrigation schedules using continuous or pulse irrigation in a commercial field of ‘Draper’ blueberry in eastern Washington, USA. The soil at the site was a silt loam, and irrigation was applied using two laterals of drip tubing per row. Plants on a fixed schedule were irrigated for 12 to 13 hours per application (set by the grower), whereas those on a weather-based schedule were irrigated according to daily estimates of crop evapotranspiration (downloaded from an automated weather station). In both cases, irrigation was applied every 2 to 4 days as a single, continuous application or in 30- to 50-minute pulses every 2 hours (up to nine times per day) with the same amount of water as the continuous treatment. During the first year of the study, weather-based scheduling maintained greater stem water potentials in the plants and, on average, increased yield by 3.4 t⋅ha–1, berry weight by 0.14 g/berry, berry diameter by 0.4 mm, and fruit bud set by 4.3% when compared with fixed scheduling. Likewise, pulse irrigation maintained greater stem water potentials and, on average, increased berry weight and diameter by 0.10 g and 0.4 mm, respectively, fruit bud set by 3.3%, and canopy cover by 2.4% relative to continuous irrigation. Yield and canopy cover were unaffected by any treatment in the second year, which was likely a result of uncharacteristically cool, wet weather in the spring. However, weather-based scheduling continued to maintain greater stem water potentials and, when combined with pulse irrigation, increased berry weight and diameter by 3.7 g and 1.0 mm, respectively, relative to continuous irrigation on a fixed schedule. Pulse drip irrigation also increased fruit bud set by 5.1% during the second year. These results demonstrate the potential benefits of using weather-based scheduling and pulse drip in northern highbush blueberry, especially when the plants are grown on light-textured soils in hot, dry climates

Surveillance guidelines for disease elimination: a case study of canine rabies

Surveillance is a critical component of disease control programmes but is often poorly resourced, particularly in developing countries lacking good infrastructure and especially for zoonoses which require combined veterinary and medical capacity and collaboration. Here we examine how successful control, and ultimately disease elimination, depends on effective surveillance. We estimated that detection probabilities of <0.1 are broadly typical of rabies surveillance in endemic countries and areas without a history of rabies. Using outbreak simulation techniques we investigated how the probability of detection affects outbreak spread, and outcomes of response strategies such as time to control an outbreak, probability of elimination, and the certainty of declaring freedom from disease. Assuming realistically poor surveillance (probability of detection <0.1), we show that proactive mass dog vaccination is much more effective at controlling rabies and no more costly than campaigns that vaccinate in response to case detection. Control through proactive vaccination followed by 2 years of continuous monitoring and vaccination should be sufficient to guarantee elimination from an isolated area not subject to repeat introductions. We recommend that rabies control programmes ought to be able to maintain surveillance levels that detect at least 5% (and ideally 10%) of all cases to improve their prospects of eliminating rabies, and this can be achieved through greater intersectoral collaboration. Our approach illustrates how surveillance is critical for the control and elimination of diseases such as canine rabies and can provide minimum surveillance requirements and technical guidance for elimination programmes under a broad-range of circumstances

Top-quark pole mass

The top quark decays more quickly than the strong-interaction time scale, \lqcd^{-1}, and might be expected to escape the effects of nonperturbative QCD. Nevertheless, the top-quark pole mass, like the mass of a stable heavy quark, is ambiguous by an amount proportional to \lqcd.Comment: 9 pages, LaTe

A Brief History of AGN

Astronomers knew early in the twentieth century that some galaxies have emission-line nuclei. However, even the systematic study by Seyfert (1943) was not enough to launch active galactic nuclei (AGN) as a major topic of astronomy. The advances in radio astronomy in the 1950s revealed a new universe of energetic phenomena, and inevitably led to the discovery of quasars. These discoveries demanded the attention of observers and theorists, and AGN have been a subject of intense effort ever since. Only a year after the recognition of the redshifts of 3C 273 and 3C 48 in 1963, the idea of energy production by accretion onto a black hole was advanced. However, acceptance of this idea came slowly, encouraged by the discovery of black hole X-ray sources in our Galaxy and, more recently, supermassive black holes in the center of the Milky Way and other galaxies. Many questions remain as to the formation and fueling of the hole, the geometry of the central regions, the detailed emission mechanisms, the production of jets, and other aspects. The study of AGN will remain a vigorous part of astronomy for the foreseeable future.Comment: 37 pages, no figures. Uses aaspp4.sty. To be published in Publications of the Astronomical Society of the Pacific, 1999 Jun

Clinical course, therapeutic responses and outcomes in relapsing MOG antibody-associated demyelination.

Abstract OBJECTIVE: We characterised the clinical course, treatment and outcomes in 59 patients with relapsing myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelination. METHODS: We evaluated clinical phenotypes, annualised relapse rates (ARR) prior and on immunotherapy and Expanded Disability Status Scale (EDSS), in 218 demyelinating episodes from 33 paediatric and 26 adult patients. RESULTS: The most common initial presentation in the cohort was optic neuritis (ON) in 54% (bilateral (BON) 32%, unilateral (UON) 22%), followed by acute disseminated encephalomyelitis (ADEM) (20%), which occurred exclusively in children. ON was the dominant phenotype (UON 35%, BON 19%) of all clinical episodes. 109/226 (48%) MRIs had no brain lesions. Patients were steroid responsive, but 70% of episodes treated with oral prednisone relapsed, particularly at doses <10\u2009mg daily or within 2 months of cessation. Immunotherapy, including maintenance prednisone (P=0.0004), intravenous immunoglobulin, rituximab and mycophenolate, all reduced median ARRs on-treatment. Treatment failure rates were lower in patients on maintenance steroids (5%) compared with non-steroidal maintenance immunotherapy (38%) (P=0.016). 58% of patients experienced residual disability (average follow-up 61 months, visual loss in 24%). Patients with ON were less likely to have sustained disability defined by a final EDSS of 652 (OR 0.15, P=0.032), while those who had any myelitis were more likely to have sustained residual deficits (OR 3.56, P=0.077). CONCLUSION: Relapsing MOG antibody-associated demyelination is strongly associated with ON across all age groups and ADEM in children. Patients are highly responsive to steroids, but vulnerable to relapse on steroid reduction and cessation

Designing programs for eliminating canine rabies from islands: Bali, Indonesia as a case study

&lt;p&gt;Background: Canine rabies is one of the most important and feared zoonotic diseases in the world. In some regions rabies elimination is being successfully coordinated, whereas in others rabies is endemic and continues to spread to uninfected areas. As epidemics emerge, both accepted and contentious control methods are used, as questions remain over the most effective strategy to eliminate rabies. The Indonesian island of Bali was rabies-free until 2008 when an epidemic in domestic dogs began, resulting in the deaths of over 100 people. Here we analyze data from the epidemic and compare the effectiveness of control methods at eliminating rabies.&lt;/p&gt; &lt;p&gt;Methodology/Principal Findings: Using data from Bali, we estimated the basic reproductive number, R0, of rabies in dogs, to be ~1·2, almost identical to that obtained in ten–fold less dense dog populations and suggesting rabies will not be effectively controlled by reducing dog density. We then developed a model to compare options for mass dog vaccination. Comprehensive high coverage was the single most important factor for achieving elimination, with omission of even small areas (&#60;0.5% of the dog population) jeopardizing success. Parameterizing the model with data from the 2010 and 2011 vaccination campaigns, we show that a comprehensive high coverage campaign in 2012 would likely result in elimination, saving ~550 human lives and ~$15 million in prophylaxis costs over the next ten years.&lt;/p&gt; &lt;p&gt;Conclusions/Significance: The elimination of rabies from Bali will not be achieved through achievable reductions in dog density. To ensure elimination, concerted high coverage, repeated, mass dog vaccination campaigns are necessary and the cooperation of all regions of the island is critical. Momentum is building towards development of a strategy for the global elimination of canine rabies, and this study offers valuable new insights about the dynamics and control of this disease, with immediate practical relevance.&lt;/p&gt

IKK phosphorylates Huntingtin and targets it for degradation by the proteasome and lysosome

Expansion of the polyglutamine repeat within the protein Huntingtin (Htt) causes Huntington's disease, a neurodegenerative disease associated with aging and the accumulation of mutant Htt in diseased neurons. Understanding the mechanisms that influence Htt cellular degradation may target treatments designed to activate mutant Htt clearance pathways. We find that Htt is phosphorylated by the inflammatory kinase IKK, enhancing its normal clearance by the proteasome and lysosome. Phosphorylation of Htt regulates additional post-translational modifications, including Htt ubiquitination, SUMOylation, and acetylation, and increases Htt nuclear localization, cleavage, and clearance mediated by lysosomal-associated membrane protein 2A and Hsc70. We propose that IKK activates mutant Htt clearance until an age-related loss of proteasome/lysosome function promotes accumulation of toxic post-translationally modified mutant Htt. Thus, IKK activation may modulate mutant Htt neurotoxicity depending on the cell's ability to degrade the modified species