Further results related to the turbulent boundary layer with slot injection of helium

Data from an experiment involving the slot injection of helium into a turbulent boundary layer in air are analyzed in terms of unconditioned and conditioned Favre-averages. The conditioning is based on two levels of helium concentration so that the contributions to the unconditioned statistics from air, helium, and mixture of these two gases can be determined. The distributions of intermittency associated with the two helium levels establish the domains of influence of air, helium, and mixture

Estimation and Inference for Threshold Effects in Panel Data Stochastic Frontier Models

One of the most enduring problems in cross-section or panel data models is heterogeneity among individual observations. Different approaches have been proposed to deal with this issue, but threshold regression models offer intuitively appealing econometric methods to account for heterogeneity. We propose three different estimators that can accommodate multiple thresholds. The first two, allowing respectively for fixed and random effects, assume that the firms specific inefficiency scores are time-invariant while the third one allows for time-varying inefficiency scores. We rely on a likelihood ratio test with m − 1 regimes under the null against m regimes. Testing for threshold effects is problematic because of the presence of a nuisance parameter which is not identified under the null hypothesis. This is known as Davies problem. We apply procedures pioneered by Hansen (1999) to test for the presence of threshold effects and to obtain a confidence set for the threshold parameter. These procedures specifically account for Davies problem and are based on non-standard asymptotic theory. Finally, we perform an empirical application of the fixed effects model on a panel of Quebec dairy farms. The specifications involving a trend and the Cobb- Douglas and Translog functional forms support three thresholds or four regimes based on farm size. The efficiency scores vary between 0.95 and 1 in models with and without thresholds. Therefore, productivity differences across farm sizes are most likely due to technological heterogeneity.Stochastic frontier models, threshold regression, technical efficiency, bootstrap, dairy production, C12, C13, C23, C52, Research Methods/ Statistical Methods,

Beyond the DSM-IV: Assumptions, Alternatives, and Alterations

Current diagnostic processes reflect the limitations and utility of the framework of the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994). Clinical information in the DSM-IV\u27s 5-axis system almost exclusively focuses on weaknesses and pathology and is summarized in a flawed categorical system. Hence, the authors describe 3 adjunctive, or alternative, means of conceptualizing behavior; several means of altering the current DSM-IV system; and 2 future directions in the diagnosis of strengths

Inter-Company Investments Between Affiliates Of Multinational Enterprises: Applying The Substance-Over-Form Doctrine To Distinguish Equity From Debt

The classification of a financial instrument as “debt” or as “equity” is crucial in applying a wide range of income tax provisions.  “Interest” expenses incurred on “debt,” for example, are deductible in computing a firm’s taxable income, whereas “dividends” paid on the firm’s outstanding “equity” are not.  “Interest” paid by a U.S. corporation to a foreign creditor is generally not subject to U.S. withholding taxes, whereas “dividends” paid on stock held by a foreign shareholder are typically subject to U.S. withholding taxes that range from 5% to 30% of the gross amount of the dividend paid.  And the list goes on . . . .  Not surprisingly, these disparities in tax treatment have inspired a plethora of schemes, many of them successful, designed to disguise equity investments as “debt.”  The urge to do so is perhaps nowhere more intense than in situations where the “debt” of a U.S. corporation is held by a foreign sister corporation located in a tax haven country.  Interest paid or accrued on debt would be deductible in computing the U.S. corporation’s U.S. taxable income, and would thereby permanently reduce the debtor’s U.S. tax liability.  The interest income earned by the foreign creditor would be exempt from both U.S. withholding taxes and income taxes in the foreign tax haven country.  This interdisciplinary case was developed from the facts and circumstances before the U.S. Tax Court in litigation that resulted from the government’s assertion that $975 million in “loans” made by a wholly owned Dutch subsidiary of Laidlaw Transit, Ltd. to several of Laidlaw’s U.S. subsidiaries were in substance “equity.”   As in most debt-versus-equity cases, the stakes were high:  Laidlaw’s U.S. subsidiaries had deducted over$133 million of intercompany “payments” made to their Dutch sister corporation as “interest expense” and the IRS was suing to recover $52 million in back taxes (plus interest and penalties).  This case integrates three disciplines – tax accounting, financial accounting, and finance -- in an easy-to-comprehend, yet rich setting appropriate for general management, finance, and accounting audiences.  It invites students to thoroughly explore the substance-over-form doctrine as it applies to the debt-versus-equity issue, together with many of the tax, financial, accounting, and economic ramifications that flow from an instrument’s classification.  It also provides students with an opportunity to identify the ethical issues that attend the formulation and implementation of many tax minimization strategies and to identify factors that separate legal “tax avoidance” from criminal “tax evasion.

Molecular mechanisms of retroviral integration site selection

Retroviral replication proceeds through an obligate integrated DNA provirus, making retroviral vectors attractive vehicles for human gene-therapy. Though most of the host cell genome is available for integration, the process of integration site selection is not random. Retroviruses differ in their choice of chromatin-associated features and also prefer particular nucleotide sequences at the point of insertion. Lentiviruses including HIV-1 preferentially integrate within the bodies of active genes, whereas the prototypical gammaretrovirus Moloney murine leukemia virus (MoMLV) favors strong enhancers and active gene promoter regions. Integration is catalyzed by the viral integrase protein, and recent research has demonstrated that HIV-1 and MoMLV targeting preferences are in large part guided by integrase-interacting host factors (LEDGF/p75 for HIV-1 and BET proteins for MoMLV) that tether viral intasomes to chromatin. In each case, the selectivity of epigenetic marks on histones recognized by the protein tether helps to determine the integration distribution. In contrast, nucleotide preferences at integration sites seem to be governed by the ability for the integrase protein to locally bend the DNA duplex for pairwise insertion of the viral DNA ends. We discuss approaches to alter integration site selection that could potentially improve the safety of retroviral vectors in the clinic

Adoption of site-specific variable rate sprinkler irrigation systems

More than 20 years of private and public research on site-specific variable rate sprinkler irrigation (SS-VRI) technology on self-propelled center pivot and linear move irrigation systems has resulted in limited commercial adoption of the technology. Competing patents, liability, and proprietary software have affected industry’s willingness to move into a new technology area. Documented and proven water conservation strategies using site specific irrigation are quite limited. Marginal costs associated with site-specific technologies are high. Although sales of SS-VRI are increasing, they are primarily being used for eliminating irrigation and chemigation on non-cropped areas of a field or for land application of liquid agricultural and municipal wastes. Various aspects of SS-VRI technologies for general crop production are beginning to slowly gain widespread acceptance; however, their uses are largely focused on addressing symptoms of poor design and suboptimal water and nutrient management. Although currently underutilized, SS-VRI technology has the potential to positively impact crop water productivity, water and energy conservation, and the environment. There are also few economic incentives to motivate growers to move to higher levels of SS-VRI management. Greater adoption rates will likely require higher costs for water and energy, severely restricted water diversions on a broad scale, and enforcement of compliance with environmental and other regulations. Sustainable use of SS-VRI will require strong research support, which is currently limited. In the short term, adoption of SS-VRI technologies will be enhanced by addressing equipment deficiencies and research developing basic criteria and systems for defining management zones and locations of various sensor systems for both arid and humid regions. Training adequate personnel to help write site-specific variable rate irrigation prescriptions in humid and arid areas to assist growers with the decision-making process is also a high priority. There is also a large need to educate government boards and bankers on the potential benefits of these systems. The long-term challenges will be to demonstrate that SS-VRI will improve water management or increase net returns. There is a critical need to develop fully integrated management systems with supporting elements that accurately and inexpensively define dynamic management zones, sense within-field variability in real time, and then adaptively control site-specific variable rate water applications, which will be challenging as significant knowledge gaps exist