Grain import dependency in the MENA region: risk management options

The Middle East and North Africa (MENA) Region is the largest grain importing region in the world. Severe constraints on arable land and water, coupled with a growing population and rising incomes, make the region inherently dependent on imports to meet rising demand for food, particularly cereals. These imports became exorbitantly expensive in recent years as world market prices for cereals were high and erratic. As a result, MENA countries, as well as food importing countries throughout the world, have placed a new premium on designing strategies for improving food security by reducing the risks that accompany being a food importing nation. This paper is meant to be an overview of strategies available to policy makers in the region in order to improve food security under the assumption of continued import dependence.     

Generalized study of crank-rocker mechanisms driven by a d.c. motor Part I. Mathematical model

A mathematical model is developed for analyzing a 4-bar linkage driven through a speed reducer by a separately-excited d.c. motor. A set of nonlinear differential equations, governing the dynamic response of this system, is derived and converted to dimensionless form. This dimensionless form is described by newly defined linkage and drive parameters. It is believed that these parameters may find convenient use in estimating the overall behavior of motor-mechanism systems from performance graphs and guidelines which can be established by numerical study of typical cases.

The performance characteristics which are considered in this analysis are the steady-state speed fluctuation of the mechanism and its steady-state energy consumption as well as the time required for mechanism “start-up” and the energy consumption during start-up. Expressions are derived in a dimensionless form to represent these performance characteristics. In Part II of this paper, specific numerical examples are presented which relate the performance characteristics to the linkage and drive parameters for two different mechanisms.     

Generalized study of crank-rocker mechanisms driven by a d.c. motor Part II. Applications

Simulation studies are performed for two different 4-bar mechanisms using separately-excited d.c. motors for actuation. The dynamic time-response analyses are carried out by means of numerical solution of the governing state equations on a digital computer. The influence of system parameters, including both motor properties and mechanism properties, on various performance characteristics is investigated, and the results are presented in the form of nondimensional graphs. These graphs help in understanding the interaction between the mechanism and its d.c. drive and are a start at obtaining generalized, quantitative information for the design of actuator-mechanism systems.     

Roots & uprisings of the RPA

Health promotion is the desired objective of dialysis treatment. Achieving the highest level of functioning not only improves the life of the patient but rewards the staff through the positive feedback that improvement produces. The facility is rewarded by a stable population producing a more secure stream of income. The therapeutic environment is improved through better communication, positive attitudes, and more active participation of patients in their care. When maximum health is the focus of care, activities to achieve health are part of routine clinical contact, not additional effort requiring more staff. Fundamental to achieving health is adequate dialysis, control of anemia, good nutrition, and attention to comorbid conditions. The "Five Es" Life Options model of rehabilitation is a pattern for pursuing health and life enhancement. Encouragement is the positive attitude and expectations for each patient. Evaluation is individualized planning and periodic assessment of progress. Education prepares the patient for participation and responsibility. Exercise (on dialysis and off) improves physical capacity and well being. Employment is sought for those of working age and capability. A number of facilities have shown the effectiveness and benefits of these practices. In addition, using health status/quality of life measures to obtain patient-reported assessment of condition allows objective scoring. Comparisons and compilations can be made to evaluate the effect of interventions or illness on status. This can be accomplished for groups or individuals to document the effect of health promotion.     

Horsefeathers: A commentary on "Evolutionary versus prototype analyses of the concept of disorder."

J. C. Wakefield's (see record 1999-03409-002) article further develops his harmful dysfunction (HD) model for disorder concepts. This commentary focuses on three areas. The first notes the imbalance in the debate between the S. O. Lilienfeld and L. Marino (see record 1995-43832-001) Roschian model and the HD model for disorder concepts. The second claims that Wakefield's purposes for the HD model have changed over the years and progressed toward irrelevance to psychopathology in general and toward irrelevance to actual nosologic, reimbursement, and sociopolitical controversies about disorder status. Further discussion is on how certain structural elements in Wakefield's arguments and current limitations of evolutionary theory permit a superficially attractive model for psychopathology. These arguments and limitations, however, harbor serious problems when confronted with actual disputes about disorders. The conclusion notes some virtues to Wakefield's inquiry, in style and substance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bounds on bearing and symbol estimation with side information

We develop Cramer-Rao bounds (CRBs) for bearing, symbol, and channel estimation of communications signals in flat-fading channels. We do this using the constrained CRB formulation of German and Hero (1990), and Stoica and Ng (see IEEE Signal Processing Lett., vol.5, p.177-79, 1998), with the unknown parameters treated as deterministic constants. The equality constraints may be combined arbitrarily, e.g., we may develop CRBs for bearing estimation of constant modulus (CM) signals where a subset of the symbols are known (semi-blind, CM case). The results establish the value of side information in a large variety of communications scenarios. We focus on the CM and semi-blind properties and develop closed-form CRBs for these cases. Examples are presented indicating the relative value of the training and CIM property. These show the significant amount of signal processing information provided under these two conditions. In addition, we consider the performance of the maximum-likelihood beamformer for the semi-blind case, assuming the bearings are known. This semi-blind beamformer achieves the appropriate (constrained) CRB with finite data at finite SNR. Analysis also reveals that in a semi-blind scenario with two closely spaced sources, ten or more training symbols are sufficient to achieve the asymptotic training regime. Together with previous results on angle estimation for known sources, these results indicate that relatively few training samples enable both angle estimation and closely spaced co-channel source separation that approaches the CRB with finite data and finite SNR     

Mycoplasma pneumoniae infection presenting as Stevens-Johnson syndrome: a case report

A case of Mycoplasma pneumoniae infection as a precipitating factor in Stevens-Johnson Syndrome is presented. As the dentist may well be the first to see this syndrome, it is appropriate to highlight the condition and this particular organism as an infective cause.     

Is who you are who you're talking to? Interpersonal style and complementarily in mixed-sex interactions.

To investigate interpersonal theory, the authors examined the social behavior of 112 previously unacquainted male-female pairs collaborating on a joint task. Structural equation modeling analyses provided clear evidence of complementarity: In addition to trait affiliation and dominance both predicting situational behavior, each interaction partner's behavior influenced the other's in accordance with the theory, eliciting similar levels of affiliation and opposite levels of dominance. There were also clear biases related to participants' interpersonal traits: When behavior, as indexed by observers, was held constant, more trait affiliative participants tended to view themselves and their partner as warmer during the interaction; likewise, more trait dominant participants perceived themselves to act more dominantly than they actually did. Throughout, there were no sex differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Source localization with distributed sensor arrays and partial spatial coherence

Multiple sensor arrays provide the means for highly accurate localization of the (x,y) position of a source. In some applications, such as microphone arrays receiving aeroacoustic signals from ground vehicles, random fluctuations in the air lead to frequency-selective coherence losses in the signals that arrive at widely separated sensors. We present performance analysis for localization of a wideband source using multiple, distributed sensor arrays. The wavefronts are modeled with perfect spatial coherence over individual arrays and frequency-selective coherence between distinct arrays, and the sensor signals are modeled as wideband, Gaussian random processes. Analysis of the Cramer-Rao bound (CRB) on source localization accuracy reveals that a distributed processing scheme involving bearing estimation at the individual arrays and time-delay estimation (TDE) between sensors on different arrays performs nearly as well as the optimum scheme while requiring less communication bandwidth with a central processing node. We develop Ziv-Zakai bounds for TDE with partially coherent signals in order to study the achievability of the CRB. This analysis shows that a threshold value of coherence is required in order to achieve accurate time-delay estimates, and the threshold coherence value depends on the source signal bandwidth, the additive noise level, and the observation time. Results are included based on processing measured aeroacoustic data from ground vehicles to illustrate the frequency-dependent signal coherence and the TDE performance.