459 research outputs found
Evaluating the Conservation Security Program utilizing the perceptions and economics of producer participation: implications for land stewardship in Iowa agriculture
Agriculture in the United States (US) has been the focus of a number of studies that address the link between on-farm agricultural practices and the degradation of natural resources. The mounting body of evidence that associates certain cropping and grazing practices with soil and waterway damage points to a need for federal agricultural policy to provide improved conservation incentives for agricultural producers. This study focuses on the first two years of the Conservation Security Program (CSP) in Iowa, a watershed based conservation program introduced with the 2002 Federal Farm Act. This new green payment program emphasizes rewarding the best stewards of natural resources and attracting the rest via reward payments and cost share incentives.;Previous studies of the CSP have been performed in a number of agricultural regions of the US including the Midwest corn belt. All have typically utilized only one research method such as interviews, focus groups, case studies or in-depth examinations of program spending. While collectively these studies have established the promise of the program as well as its limitations, this study provides a thorough examination of the CSP\u27s implemnetation in Iowa, using an approach that combines a statisitically representative mail survey of producers in the state\u27s first four CSP watersheds with 13 in-depth interviews in a complimentary manner.;Results are consistent with the findings of other studies, suggesting that the CSP is rewarding the status quo of corn, and soybean crop production in the state with little incentive for producers who have not invested previously in stewardship to improve their standards of conservation. There appears to be little to distinguish among CSP enrollees as program participants were found to be relatively homogeneous, with many already receiving payments through other conservation programs. CSP payments were found to be unevenly distributed among producers, with some probably being over compensated for the costs of their conservation which threatens program compliance with World Trade Organization (WTO) green box rules.;Rewarding producers for practices already in place is not lost on long term stewards, as enrollment in traditional conservation programs has typically allocated the highest payments to those practicing the least conservation. With the 2007 Farm Bill in mind, the effectiveness of the CSP at promoting and preserving natural resources could be greatly improved by capitalizing on the current period of high commodity prices by redirecting savings from Loan Deficiency and Counter-Cyclical payments into simplifying the CSP exclusively as a reward program for proven stewards. Additionally, conservation compliance for commodity programs should be improved and enforced so that the environmental benefits of producers practicing land stewardship is not undermined by producers unwilling to maintain conservation minimums. Promoting the CSP exclusively as a reward program should provide the needed incentive for unproven land stewards to take advantage of costshare programs such as the Environmental Quality Incentives Program (EQIP) to transition to higher levels of stewardship, increasing the overall acreage of conservation treatment in Iowa and reducing the total area of environmentally damaging practices
Economics of Breeding, Gestating and Farrowing Hogs in “Natural Pork” Production; Financial Comparison
Naturally raised pork has become a fast-growing niche market for small mid-western livestock operators. Producer marketing organizations such as Niman Ranch and Eden Natural are working to meet growing demand. While financial numbers have been comprehensively calculated for grow-finish operations in this sector, particularly with hoop production systems being compared to conventional production systems, there has been a lack of information on the breeding and farrowing stages. The objective of this report is to provide an analysis of breeding and farrowing production costs and financial analysis for naturally raised pigs in a hoop production system. A low investment pork operation typical to that of a Niman Ranch sized operation (100 breeding sows) is utilized for the analysis. The lactating period is 5 weeks with therapeutic use of antibiotics only. We will examine costs per weaner pig for different types of facilities and herd management techniques
ISU Student Organic Farm
The ISU Student Organic Farm (SOF) is a student-operated club with a mission to create a functional organic farm that meets production, educational, and marketing goals. Specifically, farm objectives are: 1) to practice and research organic production methods, 2)to educate community members and encourage active community participation, and 3) to support a local food system with a diversity of market outlets, including charitable donation
Landau theory of bi-criticality in a random quantum rotor system
We consider here a generalization of the random quantum rotor model in which
each rotor is characterized by an M-component vector spin. We focus entirely on
the case not considered previously, namely when the distribution of exchange
interactions has non-zero mean. Inclusion of non-zero mean permits
ferromagnetic and superconducting phases for M=1 and M=2, respectively. We find
that quite generally, the Landau theory for this system can be recast as a
zero-mean problem in the presence of a magnetic field. Naturally then, we find
that a Gabay-Toulouse line exists for when the distribution of exchange
interactions has non-zero mean. The solution to the saddle point equations is
presented in the vicinity of the bi-critical point characterized by the
intersection of the ferromagnetic (M=1) or superconducting (M=2) phase with the
paramagnetic and spin glass phases. All transitions are observed to be second
order. At zero temperature, we find that the ferromagnetic order parameter is
non-analytic in the parameter that controls the paramagnet/ferromagnet
transition in the absence of disorder. Also for M=1, we find that replica
symmetry breaking is present but vanishes at low temperatures. In addition, at
finite temperature, we find that the qualitative features of the phase diagram,
for M=1, are {\it identical} to what is observed experimentally in the random
magnetic alloy .Comment: 20 pages, 5 figure
Nanomechanical spectroscopy of 2D materials
We introduce a nanomechanical platform for fast and sensitive measurements of the spectrally resolved optical dielectric function of 2D materials. At the heart of our approach is a suspended 2D material integrated into a high Q silicon nitride nanomechanical resonator illuminated by a wavelength-tunable laser source. From the heating-related frequency shift of the resonator as well as its optical reflection measured as a function of photon energy, we obtain the real and imaginary parts of the dielectric function. Our measurements are unaffected by substrate-related screening and do not require any assumptions on the underling optical constants. This fast (τrise ∼ 135 ns), sensitive (noise-equivalent power = 90pW√Hz), and broadband (1.2–3.1 eV, extendable to UV–THz) method provides an attractive alternative to spectroscopic or ellipsometric characterization techniques
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Social Determinants of Health Are Associated with Markers of Renal Injury in Adolescents with Type 1 Diabetes.
OBJECTIVE: To examine the relationship between the social determinants of health and markers of early renal injury in adolescent patients with type 1 diabetes (T1D). STUDY DESIGN: Renal outcomes included estimated glomerular filtration rate (eGFR) and albumin-creatinine excretion ratio (ACR). Differences in urinary and serum inflammatory markers also were assessed in relation to social determinants of health. Regression analysis was used to evaluate the association between the Ontario Marginalization Index (ON-Marg) as a measure of the social determinants of health, patient characteristics, ACR, eGFR, and renal filtration status (hyperfiltration vs normofiltration). RESULTS: Participants with T1D (n = 199) with a mean age of 14.4 ± 1.7 years and diabetes duration of 7.2 ± 3.1 years were studied. Mean eGFR was 122.0 ± 19.4 mL/min/1.73 m2. Increasing marginalization was positively associated with eGFR (P < .0001) but not with ACR (P = .605). Greater marginalization was associated with greater median levels of urinary interleukin (IL)-2, IL-12 (p40), macrophage-derived chemokine, monocyte chemoattractant protein-3, and tumor necrosis factor-β and serum IL-2. ON-Marg was significantly associated with eGFR after we controlled for age, sex, body mass index z score, ethnicity, serum glucose, and hemoglobin A1c in linear regression. A similar association between hyperfiltration and ON-Marg score was observed in multivariable logistic regression. CONCLUSION: Increasing marginalization is significantly associated with both eGFR and hyperfiltration in adolescents with T1D and is associated with significant changes in urinary inflammatory biomarkers. These findings highlight a potentially important interaction between social and biological determinants of health in adolescents with T1D
Melting transition of an Ising glass driven by magnetic field
The quantum critical behavior of the Ising glass in a magnetic field is
investigated. We focus on the spin glass to paramagnet transition of the
transverse degrees of freedom in the presence of finite longitudinal field. We
use two complementary techniques, the Landau theory close to the T=0 transition
and the exact diagonalization method for finite systems. This allows us to
estimate the size of the critical region and characterize various crossover
regimes. An unexpectedly small energy scale on the disordered side of the
critical line is found, and its possible relevance to experiments on metallic
glasses is briefly discussed.Comment: 4 pages, 3 figure
Nanomechanical absorption spectroscopy of 2D materials with femtowatt sensitivity
Nanomechanical spectroscopy (NMS) is a recently developed approach to determine optical absorption spectra of nanoscale materials via mechanical measurements. It is based on measuring changes in the resonance frequency of a membrane resonator vs. the photon energy of incoming light. This method is a direct measurement of absorption, which has practical advantages compared to common optical spectroscopy approaches. In the case of two-dimensional (2D) materials, NMS overcomes limitations inherent to conventional optical methods, such as the complications associated with measurements at high magnetic fields and low temperatures. In this work, we develop a protocol for NMS of 2D materials that yields two orders of magnitude improved sensitivity compared to previous approaches, while being simpler to use. To this end, we use mechanical sample actuation, which simplifies the experiment and provides a reliable calibration for greater accuracy. Additionally, the use of low-stress silicon nitride membranes as our substrate reduces the noise-equivalent power to fW , comparable to commercial semiconductor photodetectors. We use our approach to spectroscopically characterize a 2D transition metal dichalcogenide (WS2), a layered magnetic semiconductor (CrPS4), and a plasmonic super-crystal consisting of gold nanoparticles
The urinary cytokine/chemokine signature of renal hyperfiltration in adolescents with type 1 diabetes.
OBJECTIVE: Urinary cytokine/chemokine levels are elevated in adults with type 1 diabetes (T1D) exhibiting renal hyperfiltration. Whether this observation extends to adolescents with T1D remains unknown. Our first objective was to determine the relationship between hyperfiltration and urinary cytokines/chemokines in normotensive, normoalbuminuric adolescents with T1D using GFR(cystatin). Our second aim was to determine the relationship between urine and plasma levels of inflammatory biomarkers, to clarify the origin of these factors. METHODS: Urine and serum cytokines/chemokines (Luminex platform) and GFR(cystatin) were measured in normofiltering (n = 111, T1D-N, GFR<135 ml/min/1.73 m(2)) and hyperfiltering (n = 31, T1D-H, GFR ≥ 135 ml/min/1.73 m(2)) adolescents with T1D (ages 10-16), and in age and sex matched healthy control subjects (HC, n = 59). RESULTS: We noted significant step-wise increases in urinary cytokine/chemokine excretion according to filtration status with highest levels in T1D-H, with parallel trends in serum analyte concentrations. After adjusting for serum glucose at the time of sampling, differences in urinary cytokine excretion were not statistically significant. Only serum IL-2 significantly differed between HC and T1D (p = 0.0076). CONCLUSIONS: Hyperfiltration is associated with increased urinary cytokine/chemokine excretion in T1D adolescents, and parallel trends in serum cytokine concentration. The GFR-associated trends in cytokine excretion may be driven by the effects of ambient hyperglycemia. The relationship between hyperfiltration, glycemia, and variations in serum and urine cytokine expression and their impact on future renal and systemic vascular complications requires further study
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