cssi/SciSciGPT-SciSciNet huggingface dataset:
Model Based Sensitivity Analysis of EMG–Force Relation with Respect to Motor Unit Properties: Applications to Muscle Paresis in Stroke

The sensitivity of the electromyogram (EMG)–force relation to changes in motoneuron and muscle properties was explored using a simulation approach, and by applying existing motoneuron pool, muscle force, and surface EMG models. The simulation results indicate that several factors contribute potently to known changes in the EMG–force relation in paretic stroke muscles. First, compression of the motor unit recruitment range with respect to the injected current tends to generate greater EMG amplitude at a given force, and to produce a highly nonlinear EMG–force relation. The overall mean slope of the EMG–force relation tends to be flatter, primarily because of this non-linear behavior. Second, with reductions of the mean motor unit firing rates, the slope of the EMG–force relation also tends to increase especially as the mean firing rates dropped substantially below the motor unit fusion frequency. Finally, similar effects were observed with a reduction in the number of motor units, and with variation in motor unit contractile properties, which also altered the EMG–force relation. These findings provide new insight toward our understanding of experimental EMG–force relations in both normal and pathological states, such as the abnormal EMG–force relations of paretis muscles in stroke.
Neuronal aggregation and neurotransmitter regulation: partial purification and characterization of a membrane-derived factor.

Abstract Cell membrane contact induces marked differential changes in neurotransmitter expression. In cultures of virtually pure dissociated sympathetic neurons, when such contact is provided by either high cell densities or addition of membranes derived from specific tissues, there is a marked increase in cell-specific content of substance P and de novo induction of choline acetyltransferase. To identify molecular mechanisms underlying regulation of transmitter expression by neuronal aggregation and membrane contact, we have begun to isolate and characterize a membrane-associated factor responsible for stimulation of choline acetyltransferase activity. The factor was found in substantial quantities in membranes from adult rat spinal cord as well as from sympathetic and sensory ganglia. Ionic mechanisms were employed to extract transmitter-inducing activity from spinal cord membranes in soluble form. The solubilized factor was then partially purified by ion exchange and gel filtration chromatography. It appears to be an extrinsic (non-integral) protein with an apparent molecular weight of 27. It is inactivated by trypsin and chymotrypsin, but is only moderately sensitive to heat inactivation, retaining activity at 60°C but not at 90°C. Neuronal perikaryal contact via aggregation represents a critical mechanism by which neurons themselves may influence phenotypic expression. Membrane localization of the factor provides a means by which cell contact may regulate transmitter expression.
Isolation, structural characterization and pharmacological activity of dog neuromedin U

Abstract The neuromedin U-like immunoreactivity in an extract of dog small intestine was resolved by reversed-phase HPLC into two molecular forms. The primary structure of the larger form (NMU-25) was established as: Phe-Arg-Leu-Asp-Glu-Glu-Phe-Gln-Gly-Pro10-Ile-Ala-Ser-Gln-Val-Arg-Arg-Gln-Phe-Leu20-Phe-Arg-Pro-Arg-Asn-NH2. This sequence shows five substitutions relative to pig neuromedin U-25. The primary structure of the second peptide (NMU-8) was established as: pGlu-Phe-Leu-Phe-Arg-Pro-Arg-Asn-NH2. The sequence contains the substitution pGlu for Tyr1 compared with pig neuromedin U-8. The potency of synthetic dog NMU-8 in contracting smooth muscle from the rat uterus ( EC 50 10±2 nM ; mean ± S.E., n =6 ) was not significantly different from the corresponding potency of pig NMU-8 ( EC 50 16±5 nM ) but the maximum response produced by the dog peptide was greater (58%; p ) than that produced by pig NMU-8.
Importance of lymph node metastases in primary peritoneal carcinoma

Background and Objectives: The incidence and significance of lymph node involvement in patients with primary peritoneal adenocarcinoma (PPA) are unknown. The aim of the current study is to report on the incidence and significance of clinically or surgically detectable lymphadenopathy in women with PPA. Methods The study is a retrospective clinical review of patients with the confirmed diagnosis of PPA treated at Roswell Park Cancer Institute between 1982 and 1996. Patients with clinically or surgically detectable lymphadenopathy confirmed on histologic examination to be secondary to metastases from PPA were identified and compared to patients with negative lymph nodes with regard to clinicopathologic characteristics, treatment, response to treatment, and survival. Results Seventy-two patients with PPA were identified. Pelvic and periaortic lymph node biopsies or sampling were performed in 35% of the patients. In 8/72 patients (11%), lymphadenopathy was one of the presenting clinical or surgical findings. The clinicopathologic features, treatment, response to first-line chemotherapy, and estimated median overall survival were not different in patients with or without lymph node involvement (71.4% vs. 69.7%, P = 1.0, and 21.5 vs. 23.5 months, P = 0.14). Conclusions Lymph node involvement is not an infrequent occurrence in patients with PPA and does not seem to be of adverse prognostic significance. J. Surg. Oncol. 1998;68:144–148. © 1998 Wiley-Liss, Inc.
Depressive symptoms and sleepiness among Latino farmworkers in eastern North Carolina.

ABSTRACT Depression and sleepiness are both risk factors for occupational accidents and unintentional injury. Relatively little is known about the experiences of these risk factors in the immigrant Latino farmworker population. This analysis uses prospective panel data from a sample of Latino farmworkers in eastern North Carolina that were collected at monthly intervals during the 2008 agricultural season to (1) describe depressive symptoms and daytime sleepiness among immigrant Latino farmworkers across the agricultural season; (2) delineate associations of depressive symptoms with sleepiness across time; and (3) determine whether depressive symptoms precede sleepiness, or if sleepiness precedes depressive symptoms. Results indicated that 45% of farmworkers experienced elevated depressive symptoms across the season, whereas 20% experienced elevated sleepiness. Elevated depressive symptoms were more common among farmworkers living in barracks, and less common among those living in trailers. Sleepiness was...
Advances in collaborative evaluation.

Collaborative evaluation is an approach that offers, among others, many advantages in terms of access to information, quality of information gathered, opportunities for creative problem-solving, and receptivity to findings. In the last decade, collaborative evaluation has grown in popularity along with similar participatory, empowerment, and utilization-focused evaluation approaches. Increasingly, it has brought together evaluators and stakeholders from different sectors, disciplines, and cultures to exchange knowledge on how collaboration can be used as a strategic tool for fostering and strengthening evaluation practice. O'Sullivan (2004) and Rodriguez-Campos (2005, 2008) brought forward collaborative evaluation conceptual frameworks that distinguished it from other approaches. This article updates those conceptual frameworks and discusses key collaborative evaluation advances in order to further clarify and facilitate engagement in sound practice.
Adequacy of well-child care and immunization.

To the Editor. —We are concerned that the otherwise valuable study by Dr Mustin and colleagues 1 has been misinterpreted by the media and will be similarly misunderstood by others unaware of the limitations of secondary data analysis. Mustin et al 1 concluded that while most US infants have adequate well-child visits, many remain inadequately immunized. The authors defined adequate well-child visits as one prior to 3 months of age plus one between the ages of 3 and 6 months. They defined adequate immunization as receipt of three diphtheria and tetanus toxoids and pertussis (DTP) vaccines and two oral poliomyelitis vaccines (OPVs) by 6 months of age. Because three visits at least 4 weeks apart are required to administer these immunizations, by the authors' definitions many infants will be classified as having received adequate well-child visits, but will be inadequately immunized at 6 months of age. Furthermore, some of the
Rapidity of freshwater calcite cementation—implications for carbonate diagenesis and sequence stratigraphy

Abstract In less than 10 years, subaerially-exposed Holocene oolitic sand on Eleuthera Island, Bahamas was completely case-hardened by freshwater vadose calcite cementation. This phenomenon demonstrates the rapidity of freshwater carbonate diagenesis and explains, in part, why carbonate platforms preferentially shed unconsolidated sediment during highstands and not during lowstands when they are subaerially exposed. It further proves, contrary to what the Exxon conceptual sequence stratigraphic models imply, that carbonate deposits do, in fact, respond differently to subaerial exposure than siliciclastic deposits. Case hardening of unconsolidated carbonate sediment in response to subaerial exposure and early, near-surface freshwater diagenesis helps explain why shallow-water platform sediments are preferentially shed into adjacent basins during highstands of sea level and not during lowstands. During lowstands, rapid subaerial lithification of carbonate sediments retards their reworking by wind or water. Once lithified, these deposits are further stabilized by vegetation and karstification, inhibiting their transport as unconsolidated sediment into adjacent deeper-water basins. Observations from Eleuthera Island also document the reciprocal processes associated with freshwater carbonate diagenesis. Calcium carbonate released by partial dissolution of aragonitic ooids was locally reprecipitated as pore-filling, low-magnesian calcite cement. This reciprocity is confirmed by the confinement of freshwater dissolution and cementation to the upper 10–20 cm of the subaerially-exposed body of oolitic sand. Below this case-hardened surface, oolitic sands remained unconsolidated. Only very minor amounts of calcite cement were required for effective casae hardening.
Synthesis of Modular Headgroup Conjugates Corresponding to All Seven Phosphatidylinositol Polyphosphate Isomers for Convenient Probe Generation

Phosphatidylinositol polyphosphate lipids (PIPns) play key roles in important biological pathways, and defects in the signaling activities of these molecules have been implicated in a number of disease states. As such, it is necessary to understand the complex roles of these lipids in biological pathways, which often involve their actions as site-specific ligands that recruit receptors to the surfaces of cellular membranes. However, the complex structures of PIPn family members, of which seven biologically active isomers exist, complicate studies. Derivatized analogs of the PIPn structures are beneficial as chemical tools for elucidating signaling and binding activities. Herein, we present an efficient approach to probe the generation in which amino conjugates of PIPn headgroups can be conveniently functionalized in the final step of the synthesis to obtain a number of derivatized analogs of use for different studies. In addition to the application of this strategy to generate PI-(4,5)-P2 headgroup probes, we also report the synthesis of PIPn–amine conjugates corresponding to all seven naturally existing isomers. This approach will be invaluable for generating the range of probe structures that is required to elucidate the intricacies of PIPn signaling. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
A two step stain for normal and leukemic monocytes using two different dyes applied in sequence.

A staining procedure for monocytes in specimens of blood and bone marrow was developed. The technique was a two step procedure in which unfixed cells were exposed first to a methanolic solution of C.I. basic blue 54. Next, an aqueous alkaline buffered solution of C.I. basic blue 141 was added to the first staining solution. After staining for 10 min in the solution with two stains, slides or coverslips were washed for 5 sec in pH 5.6 phosphate buffer and drained dry. The cytoplasm of monocytes stained intensely deep purple and frequently nuclei were stained red. Similar staining was not found in other types of normal or abnormal blood and bone marrow cells.
Modal Mereology and Modal Supervenience

David Lewis insists that restrictivist composition must be motivated by and occur due to some intuitive desiderata for a relation R among parts that compose wholes, and insists that a restrictivist’s relation R must be vague. Peter van Inwagen agrees. In this paper, I argue that restrictivists need not use such examples of relation R as a criterion for composition, and any restrictivist should reject a number of related mereological theses. This paper critiques Lewis and van Inwagen (and others) on their respective mereological metaphysics, and offers a Golden Mean between their two opposite extremes. I argue for a novel account of mereology I call Modal Mereology that is an alternative to Classical Mereology. A modal mereologist can be a universalist about the possible composition of wholes from parts and a restrictivist about the actual composition of wholes from parts. I argue that puzzles facing Modal Mereology (e.g., puzzles concerning Cambridge changes and the Problem of the Many, and how to demarcate the actual from the possible) are also faced in similar forms by classical universalists. On my account, restricted composition is rather motivated by and occurs due to a possible whole’s instantiating an actual type. Universalists commonly believe in such types and defend their existence from objections and puzzles. The Modal Mereological restrictivist can similarly defend the existence of such types (adding that such types are the only wholes) from similar objections and puzzles.
Racial difference in diabetes preventive care

Abstract Background Diabetes has long been a leading cause of death in the United States, and worldwide. Diabetes-related preventive services are recommended to delay or to avoid diabetes complications. Racial disparity in the receipt of diabetes preventive care is well documented; however, little is known about the contributors to this disparity. Objective This study aims to explore potential mediators linking race/ethnic disparities to reduced receipt of preventive care, and to better understand the dynamics underlying the relationships between race/ethnic characteristics and preventive care. Implications for pharmacist roles are explored. Methods This study used 2008 Medical Expenditure Panel Survey (MEPS) data. The outcome of diabetes preventive care was assessed by participants' self-reports in MEPS. Household income and health insurance coverage were identified as potential mediators based on Andersen's Health Care Utilization Behavior model. Logistic regression was used to examine the direct effects of study independent variables on diabetes preventive care. Path analysis was conducted to identify racial disparities' direct and indirect effects on diabetes preventive care via potential mediators. All estimates were weighted to the U.S. non-institutionalized population. Results Racial differences occurred with respect to receiving A1C tests, diabetic foot exams, and eye exams. After controlling for patient age, gender, living area, income, and health insurance status, racial differences persisted in diabetes preventive care. Hispanics were the least likely to receive all three elements of diabetes preventive care. In addition, patients were less likely to receive diabetes preventive care who were younger, lived in rural areas, had lower family income and were uninsured. A lower rate of diabetes preventive care in minority patients was partially explained by their higher rate of being uninsured or having low family income. Conclusion The results suggest that minority, rural, low-income, uninsured, and young diabetes patients are at a higher risk of not receiving diabetes preventive care. This study is unique in its use of path analysis to assess racial disparities in diabetes preventive care and to do so drawing on Andersen's Health Care Utilization Behavior model. In response to the disparity findings which were reinforced in this study, pharmacists have a need and an opportunity to help identify and address important gaps in diabetes preventive care through diabetes patient assessment, education, referral, and monitoring.
Mutational analysis of ion conduction and drug binding sites in the inner mouth of voltage-gated K+ channels

Pore properties that distinguish two cloned, voltage-gated K+ channels, Kv2.1 and Kv3.1, include single-channel conductance, block by external and internal tetraethylammonium, and block by 4-aminopyridine. To define the inner mouth of voltage-gated K+ channels, segmental exchanges and point mutations of nonconserved residues were used. Transplanting the cytoplasmic half of either transmembrane segments S5 or S6 from Kv3.1 into Kv2.1 reduced sensitivity to block by internal tetraethylammonium, increased sensitivity to 4-aminopyridine, and reduced single-channel conductance. In S6, changes in single-channel conductance and internal tetraethylammonium sensitivity were associated with point mutations V400T and L403 M, respectively. Although individual residues in both S5 and S6 were found to affect 4-aminopyridine blockade, the most effective change was L327F in S5. Thus, both S5 and S6 contribute to the inner mouth of the pore but different residues regulate ion conduction and blockade by internal tetraethylammonium and 4-aminopyridine.
Correlation in VHF propagation over irregular terrain

A study has been made of the correlation in transmission loss observed over irregular-terrain paths. Simultaneous mobile measurements were made of two pairs of VHF broadcasting stations in the Washington, D. C-Baltimore, Maryland area. The correlation coefficients derived from sample sets of transmission loss data indicate that when reception is from opposite directions, no significant correlation is evident, and when the paths of propagation are the same even though the frequencies are separated considerably, the correlation appears to be significantly high.
Array Observations of Microseismic Noise and the Nature of H/V in the Mississippi Embayment

Abstract Ambient ground-motion data were collected using phased seismic arrays in fall 2002 and spring 2007 within the Mississippi embayment and at a single station external to the embayment. These data allowed us to determine the wave-field composition of ambient noise for understanding wave-propagation mechanisms giving rise to spectral peaks using Nakamura’s H/V technique. Ambient ground motions in the frequency band of 0.1–0.33 Hz (10–3 sec period) were dominated by spatially localized Rayleigh- and Love-wave microseisms generated by high-ocean waves along the North American seaboard in the time periods of analysis. Seismic waves important in forming the H/V peak near 4 sec period are composed of relatively high-phase velocity Rayleigh and Love waves that convert to propagating homogeneous shear waves in the thick unconsolidated sediments of the embayment. The H/V resonant period is controlled by both constructive and destructive interference of these shear waves. A simple relationship for the H/V peak is given using a propagator matrix formulation that predicts the resonance frequency of a layered medium for surface wave motion at the base of the system. The amplitude of the observed H/V peak, however, does not give an accurate estimate of shear-wave amplification because it depends on the slowness of the incident wave. The inconsistency in estimated average shear-wave velocities using the H/V method and differential travel times of local earthquake Sp phases in the Mississippi embayment may be explained by misidentification of Sp -wave conversion points from deeper interfaces.
Overcoming drug resistance in chronic myeloid leukemia

Purpose of reviewDespite the excellent clinical results with imatinib in chronic myeloid leukemia, most patients have minimal residual disease and others will develop resistance and may eventually progress. Thus there is a need for developing approaches to overcome and prevent resistance to imatinib
Impact of spatially and temporally varying estimates of error covariance on assimilation in a simple atmospheric model

The background error covariance (correlation) between model state variables is of central importance for implementing data assimilation and understanding model dynamics. Traditional approaches for estimating the background error covariance involve many heuristic approximations, and often the estimated covariance is flow-independent, i.e. only reflecting statistics of the climatological background. This study examines temporally and spatially varying estimates of error covariance in a spectral barotropic model using a Monte Carlo approach, an implementation of an ensemble square root filter called the ensemble adjustment Kalman filter (EAKF). The EAKF is designed to maintain as much information about the distribution of the prior state variables as possible, and results show that this method can produce reasonable estimates of error correlation structure with an affordable sample (ensemble) size. The impact of using temporally and spatially varying estimates of error covariance in the EAKF is examined by using the time and spatial mean error covariances derived from the EAKF in an ensemble optimal interpolation (OI) assimilation scheme. Three key results are: (1) for the same ensemble size, an ensemble filter such as the EAKF produces better assimilations since its flow-dependent error covariance estimates are able to reflect more about the synoptic-scale wave structure in the simulated flows; (2) an ensemble OI scheme can also produce reasonably good assimilation results if the time-invariate covariance matrix is chosen appropriately; (3) when using the EAKF to estimate the error covariance matrix for improving traditional assimilation algorithms such as variational analysis and OI, a relatively small ensemble size may be used to estimate correlation structure although larger ensembles produce progressively better results.
Prospective life-cycle modeling of a carbon capture and storage system using metal–organic frameworks for CO2 capture

Metal–organic frameworks (MOFs) are promising new material media for carbon dioxide (CO2) capture. Their tunable adsorption patterns may allow relatively efficient separation of gases, e.g. from power plant exhaust. Here we conduct scenario-based prospective life-cycle system modeling to estimate the potentials and implications of large-scale MOF application for post-combustion carbon capture and storage (CCS), and estimate the source and magnitude of uncertainties. The methodological approach includes parametric system modeling to quantify relations between system components; scenario projections of plausible pathways for system scale-up; proxy data on analogous materials and processes; and uncertainty analysis of parameter significance. We estimate the system-wide material and energy flows and economic costs associated with projected large-scale CCS deployment. We compare the performance of a MOF-based system to currently more mature amine-based capture technology. We discuss balancing two critical factors that determine the success of CO2 capture media: thermodynamic efficiency of the capture/regeneration cycle, and life-cycle embodied energy and cost of the material and its ancillary systems.
Genetic algorithm-based induction machine characterization procedure with application to maximum torque per amp control

There has been considerable research in developing improved induction motor models. One recently developed model simultaneously includes magnetizing path saturation, leakage saturation, and a highly flexible transfer function approach to represent the rotor circuits. This alternate QD model (AQDM) is also computationally efficient in that it is noniterative at each time step. It is considerably more accurate than the classical QD model (CQDM). However, the suggested characterization procedure is complicated and time consuming. This paper proposes a new characterization procedure for the AQDM. The proposed procedure employs a genetic algorithm (GA) as an optimization engine to identify the parameters of the AQDM by simultaneously considering per-phase fundamental frequency impedance and stand-still frequency response (SSFR) impedance. The proposed approach is validated by comparison of current ripple predictions (to validate high-frequency model behavior) and by application to maximum torque per ampere control design (to validate fundamental frequency model behavior). The proposed procedure is significantly more straightforward than the other published method of obtaining AQDM parameters.
Bosnian immigrants' perceptions of the United States health care system: a qualitative interview study.

During the 1990s, approximately 300,000 Bosnian immigrants came to the United States as a result of the Balkan wars. In contrast to immigrants from less developed countries, Bosnian refugees were typically older, had experienced significant war related trauma, and were accustomed to universal health insurance coverage. There is little information about Bosnian immigrants' transition to the U.S. health care system. As part of a related project, 12 Bosnian immigrants were interviewed about their perceptions of the U.S. health care system and their experiences as patients. Participants were universally critical of the U.S. system and described several core issues: confusion about insurance coverage, personalized quality of care, access to primary and specialty care; and a perception of U.S. health care as bureaucratic. Participants compared their experience with prewar Bosnian health care along these dimensions. Implications of the findings and suggestions for improving care to the Bosnian immigrant population are provided.
The Valence Electronic Structure of Co3O4: Is It a Charge-Transfer Insulator?

Despite the relevance to a variety of materials applications, the electronic and bonding properties of spinel transition metal oxides are not well established. We report here the slow oxidation of CoO(100) to Co3O4, studied by photoemission (UPS and XPS), low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS) with the aim of elucidating the valence band electronic structure of the Co3O4 spinel. The original Mott insulator picture of the parent CoO substrate has been revised in recent times, after careful analyses and extensive debate, to the more detailed charge-transfer insulator model which includes some admixture of oxygen 2p levels in the 3d-derived valence band. No equivalent band structure analysis has been performed on the spinel oxides, perhaps in part because of the greater complexity of the 56-atom unit cell with two different cation lattice sites and oxidation states. In this study, we determine the valence band structure of the spinel oxide and address the question of whether Co3O4 can be modeled as a charge-transfer insulator in analogy with its closely related rocksalt substrate.
Magnetic noise associated with ocean internal waves

Environmental noise can be a major limitation on the performance of magnetic sensor systems in continental shelf regions. Previous work has predicted the magnetic influence from internal waves and indicates that these could be important components of ambient ocean magnetic noise. Existing electric and magnetic field sensor technology has an instrument noise floor well below the ambient magnetic noise in shallow water applications. Model predictions indicate that internal oceanographic features, such as high amplitude internal waves, internal bores and solitary waves, can contribute magnetic variations in the very low frequency band ranging from 0.1 to 1.0 nT which is well above the noise level of commercial magnetometer systems. Predictions of the magnetic character for internal ocean dynamics are computed using a nested non-hydrostatic ocean model coupled with a simple electromagnetic model. These predictions should correlate with oceanographic observations of water velocity. Comparison of the model predictions with observed oceanographic measurements is under investigation.
Assessing Quality of Policy Properties in Verification of Access Control Policies

Access control policies are often specified in declarative languages. In this paper, we propose a novel approach, called mutation verification, to assess the quality of properties specified for a policy and, in doing so, the quality of the verification itself. In our approach, given a policy and a set of properties, we first mutate the policy to generate various mutant policies, each with a single seeded fault. We then verify whether the properties hold for each mutant policy. If the properties still hold for a given mutant policy, then the quality of these properties is determined to be insufficient in guarding against the seeded fault, indicating that more properties are needed to augment the existing set of properties to provide higher confidence of the policy correctness. We have implemented Mutaver, a mutation verification tool for XACML, and applied it to policies and properties from a real-world software system.
Observation and quantification of ultraviolet-induced reactive oxygen species in ex vivo human skin.

Abstract Two-photon fluorescence imaging is used to detect UV-induced reactive oxygen species (ROS) in ex vivo human skin in this study. ROS (potentially H2O2, singlet oxygen or peroxynitrite [or all]) are detected after reaction with nonfluorescent dihydrorhodamine-123 (DHR) and the consequent formation of fluorescent rhodamine-123 (R123). The cellular regions at each epidermal stratum that generate ROS are identified. R-123 fluorescence is detected predominately in the lipid matrix of the stratum corneum. In contrast, the strongest R123 fluorescence signal is detected in the intracellular cytoplasm of the viable epidermal keratinocytes. A simple bimolecular one-step kinetic model is used for estimating the upper bound of the number of ROS that are generated in the skin and that react with DHR. After ultraviolet-B radiation (280–320 nm) (UVB) equivalent to 2 h of noonday summer North American solar exposure (1600 J m−2 UVB), the model finds that 14.70 × 10−3 mol of ROS that react with DHR are generated i...
Design and Analysis of a Sensing Error-Aware MAC Protocol for Cognitive Radio Networks

In this paper, we present a spectrum sensing error-aware MAC protocol for a cognitive radio (CR) network collocated with multiple primary networks. We explicitly consider sensing errors in the CR MAC design, since such errors are inevitable for practical spectrum sensors. Two spectrum sensing polices are presented with which secondary users collaboratively sense the licensed channels. The sensing policies are then incorporated into p-Persistent CSMA to coordinate dynamic spectrum access for CR network users. We present an analysis of the interference and throughput performance of the proposed CR MAC, and find the analysis highly accurate in our simulation studies. The proposed sensing error-aware CR MAC protocol outperforms two existing approaches with considerable margins in our simulations, which justify the importance of considering spectrum sensing errors in CR MAC design.
ENERGETIC AND ECONOMIC FEASIBILITY ASSOCIATED WITH THE PRODUCTION, PROCESSING, AND CONVERSION OF BEEF TALLOW TO A SUBSTITUTE DIESEL FUEL

Abstract This study investigates the resource availability, energetic efficiency, and economic feasibility of converting edible and inedible beef tallow into biodiesel, a substitute diesel fuel. A resource assessment of edible and inedible beef tallow generation in the United States was performed for the period of 1997–2001. At that time, an average of more than 1.8 Mt (4 billion pounds) of edible and inedible tallow were generated each year in the 11 largest commercial cattle slaughtering states, which would equate to more than 2.08 GL (551 million gallons) of biodiesel (∼1% of the total US distillate consumption). Tallow is a by-product of our meat production and processing system, which complicates its energy and economic analysis. Although tallow is available in significant quantities at relatively low cost, it is not intentionally produced as a feedstock for biodiesel. Because of this uncertainty, energetic (energy ratio) and economic (production cost per gallon) feasibilities were estimated for three different system boundaries: (1) conversion of tallow by a continuous-flow transesterification process only with co-product (glycerin) credit, (2) rendering plant operations plus tallow transesterification, and (3) growth and maintenance of the beef animal from conception through rendering and transesterification. Energy ratios varied from 17.29 to 0.81 within the three system boundaries based on various assignments of the co-product energy credit for glycerin. Cost-sensitivity analyses were performed to determine the effect of feedstock cost and by-product (glycerin) credit on biodiesel cost. Feedstock cost had the greatest impact, while by-product credit effect was minimal. Cost of production ranged from $0.22 to $0.63 L −1 ($0.82–$2.38 gallon −1 ) produced.
Studies of contractile force in man. The effects of myocardial hypothermia or coronary perfusion during aortic occlusion.

Forty-five patients undergoing open-heart surgery for acquired aortic valve disease were studied with measurements of left ventricular contractile force. The data presented clearly indicate that coronary perfusion afforded, on the average, better protection to left ventricular contractility as recorded by a strain-gage arch than did hypothermia. This was particularly true in the usual case, which required an hour or longer of aortic occlusion. Patients who required 40 minutes or less of aortic occlusion demonstrated approximately identical decreases in contractile force with hypothermia or coronary perfusion. Bilateral coronary perfusion did not usually afford much additional left ventricular protection as compared to unilateral left coronary perfusion. In a small number of patients with significant coronary arterial occlusion, bilateral coronary perfusion appeared to give better left ventricular protection.
Bathtub dynamics: initial results of a systems thinking inventory

In a world of accelerating change, educators, business leaders, environmentalists and scholars are calling for the development of systems thinking to improve our ability to take effective actions. Through courses in the K-12 grades, universities, business schools, and corporations, advocates seek to teach people to think systemically. These courses range from one-day workshops with no mathematics to graduate level courses stressing formal modeling. But how do people learn to think systemically? What skills are required? Does a particular type of academic background improve one’s ability to think systemically? What systems concepts are most readily understood? Which tend to be most difficult to grasp? We describe initial results from an assessment tool or systems thinking inventory. The inventory consists of brief tasks designed to assess particular systems thinking concepts such as feedback, delays, and stocks and flows. Initial findings indicate that subjects from an elite business school with essentially no prior exposure to system dynamics concepts have a poor level of understanding of stock and flow relationships and time delays. Performance did not vary systematically with prior education, age, national origin, or other demographic variables. We hope the inventory will eventually provide a means for testing the effectiveness of training and decision aids used to improve systems thinking skills. We discuss the implications of these initial results and explore steps for future research. Copyright © 2000 John Wiley & Sons, Ltd.
Pathogenesis of Helicobacter pylori infection

Helicobacter pylori induces chronic gastritis, the strongest known risk factor for peptic ulcer disease and distal gastric cancer, yet only a fraction of colonized individuals ever develop clinical disease. H. pylori isolates possess substantial genotypic diversity, which engenders differential host inflammatory responses that influence pathologic outcome. However, clinical sequelae are not completely dependent upon bacterial virulence factors, and disease is also influenced by host genetic diversity, particularly within immune response genes. The focus of this article will be to provide an understanding of mechanisms that underlie H. pylori persistence and pathogenesis as a framework for understanding disease processes that develop from chronic inflammation. Identification of mechanisms that regulate ongoing H. pylori–host interactions will not only improve targeted diagnostic and therapeutic modalities, but may also provide insights into other diseases that arise within the context of pathogen-initiated inflammatory states.
Performance analysis of distributed intrusion detection protocols for mobile group communication systems

Under highly security vulnerable, resource restricted, and dynamically changing mobile ad hoc environments, it is critical to be able to maximize the system lifetime while bounding the communication response time for mission-oriented mobile groups. In this paper, we analyze the tradeoff of security versus performance for distributed intrusion detection protocols employed in mobile group communication systems (GCSs). We investigate a distributed voting-based intrusion detection protocol for GCSs in multi-hop mobile ad hoc networks and examine the effect of intrusion detection on system survivability measured by the mean time to security failure (MTTSF) metric and efficiency measured by the communication cost metric. We identify optimal design settings under which the MTTSF metric can be best traded off for the communication cost metric or vice versa.
Magnesium in the 1990's: Implications for Veterinary Critical Care

Summary Magnesium is the second most abundant intracelular cation, exceeded only by potassium. The majority of magnesium is found in bone and muscle. This cation is required for many metabolic functions, most notably as a coenzyme for the sodium-potassium ATPase pump. Magnesium functions to maintain the electrolyte gradient across all membranes. Interference with this gradient may result in changes in the resting membrane potential and disturbances in repolarization, resulting in cardiovascular and neuromuscular abnormalities. Hypomagnesemia may be the most underdiagnosed electrolyte disorder. Incidence rates greater than 50 percent have been reported in critically ill human patients. Currently there is little or no information available regarding the incidence and significance of hypomagnesemia in hospitalized animals. Causes of magnesium deficiency can be divided into four general categories: gastrointestinal, renal, endocrine and miscellaneous. The diagnosis of magnesium depletion can be difficult since less than one percent of total body magnesium is located in serum. Alternative methods of evaluating magnesium status include determining ultrafilterable magnesium levels, mononuclear blood cell magnesium levels or by quantifying magnesium retention of an administered loading dose.
Solute response to changing nutrient loads in soil and walled ceramic cup samplers under continuous extraction.

This report evaluates a vacuum-assisted walled percolation sampler preconditioned in soil, and examines the dynamic response of leachate solutes. The 20-cm walled percolation sampler extracted soil water under continuous tension via a ceramic cup collector embedded in a silica flour layer, whose upper surface interfaced with field soil. In the laboratory, alternating solutions with high and low NO3-N (232 or 3.6 mg L-1), molybdate-reactive P (MRP) (1.75 or 0.0 mg L -1), K+ (568 or 3.6 mg L-1), and Br- (9.6 or 0.0 mg L-1) concentrations were delivered directly to the (i) sampler ceramic cup; (ii) silica flour bed surface, or (iii) 12-mm soil layer placed over the silica flour bed. For alternating input solutions delivered to the silica-flour bed surface, (i) solute breakthrough (95% equivalency) occurred in 4 pore volumes and was the same for both the high and low concentration input phases of the application, and (ii) concentrations of NO 3-N, Br-, and MRP in cumulative extracted water volumes were within 5% of those in corresponding input volumes. Alternating nutrient loads from high to low levels in the fixed flow rate input waters caused excess MRP (L6 times that in the high concentration MRP solution) to leach from the calcareous soil. The dynamic character of P transport in K-fertilized soils deserves further study and may have important environmental implications.
The Myth of the Elite Cue Influence of Voters’ Preferences on the US Congress

While various scholars of public opinion in the United States explain that the ideology of partisan legislators influences the preferences of partisan voters, the literature within the paradigm of represen tational politics maintains the reverse�that partisan voters� ideology affects legislators� voting preferences. By employing Vector Autoregression analysis, this article examines whether changes in the preferences of US Congress members lead to changes in the ideology of partisan voters, or vice versa. The findings indicate that the legislators� ideology in the House or Senate has no impact on the preferences of partisan voters as measured by the ANES seven-point ideology scale. Rather, Democratic voters� ideological shift influences the change in Democratic members� preferences in both the Senate and the House. However, Republican voters do not exert equivalent influence on GOP legislators.
Lidar observations of ship spray plumes

As part of the Monterey Area Ship Track experiment, which was designed to study ship-generated cloud tracks, ship-based measurements were made by a gyroscopically stabilized scanning lidar system. This paper focuses on the spray plume observed by lidar behind the USS Truxton, a nuclear-powered surface ship. Measurements are included from five passes at different speeds. Observed parameters include the speed of the plume meander, maximum speed of vertical mixing, and dispersion time.
A sequential algorithm for multiblock orthogonal projections to latent structures

Methods of multiblock bilinear factorizations have increased in popularity in chemistry and biology as recent increases in the availability of information-rich spectroscopic platforms has made collecting multiple spectroscopic observations per sample a practicable possibility. Of the existing multiblock methods, consensus PCA (CPCA-W) and multiblock PLS (MB-PLS) have been shown to bear desirable qualities for multivariate modeling, most notably their computability from single-block PCA and PLS factorizations. While MB-PLS is a powerful extension to the nonlinear iterative partial least squares (NIPALS) framework, it still spreads predictive information across multiple components when response-uncorrelated variation exists in the data. The OnPLS extension to O2PLS provides a means of simultaneously extracting predictive and uncorrelated variation from a set of matrices, but is more suited to unsupervised data discovery than regression. We describe the union of NIPALS MB-PLS with an orthogonal signal correction (OSC) filter, called MB-OPLS, and illustrate its equivalence to single-block OPLS for regression and discriminant analysis.
FACTORES QUE PREDISPONEN A LA INGESTIÓN DE PLANTAS TÓXICAS POR EL GANADO

El diagnostico de intoxicaciones por plantas toxicas suele ser dificil, ya que en la mayoria de los casos se producen cuadros no especificos que deben diferenciarse de otras enfermedades. Si el veterinario esta familiarizado con las plantas del medio y las condiciones que predisponen a intoxicaciones por vegetales puede llegar a hacer un diagnostico presuntivo identificando la planta en el forraje o pasto, evidenciando el consumo por parte del animal y reconociendo un cuadro clinico esperado por ingestion de dicha planta. En este trabajo se describen los principales factores desencadenantes que favorecen la aparicion de intoxicaciones por plantas y que abarcan las condiciones medioambientales, practicas agricolas y de manejo del ganado. Puesto que los herbivoros por lo general rechazan consumir plantas nocivas en su medio natural, tambien se explican cuales son los mecanismos de conducta que utilizan para seleccionar su dieta. Por ultimo, se describen los metodos corrientes de prevencion y tambien se expone un caso clinico tipico producido por Senecio jacobea y cuya presentacion es similar a la que puede observarse por el Senecio inaequidens en Colombia. Abstract The diagnosis of plant-related toxicosis can be most challenging due to the lack of specific signs that can also relate to other disease conditions. When veterinarians are familiar with the toxic plants in their area and the factors favoring intoxications, a presumptive diagnosis can be made through: a) identification of the plant on the field and/or forage, b) evidence of consumption and, c) relating the disease state of the animal to that expected from exposure to the suspect plant. This report describes those conditions that favor plant-related toxicosis, including adverse climatic conditions, agricultural practices and animal management practices. Since herbivores usually avoid consuming toxic plants, the report also explains the basic mechanisms by which animals select their diet. General preventive measures to avoid plant intoxications are also addressed together with a typical field case caused by Senecio jacobea . A similar toxic plant, Senecio inaequidens , is likely to cause similar cases in Colombia.
Trellis group codes for the Gaussian channel

In this paper, trellis group codes are introduced as an extension of Slepian group codes to codes over sequence spaces. A trellis group code is defined over R/sup n/ as the orbit of a bi-infinite "seed sequence", x/sub 0//spl isin/(R/sup n/)/sup Z/, under an infinite, defining group of transformations. This group of transformations is generated by a symbolic system. The theory is developed by combining a nontrivial extension of the notion of an isometric labeling, with results from the theory of symbolic dynamics over groups. New results presented here include a useful characterization of uniform partitions and a symbolic dynamic classification of trellis group codes. The theory is used to develop a class of rotationally invariant, nonabelian trellis group codes for QAM modulation. It is also shown that the 8-state, rotationally invariant trellis code designed by Wei (1984), used in the V.32 (and V.32 bis) international modem standard, belongs to this class. >
Research in improving self‐concept in the basic course: Review and recommendations

Analysis of current research suggests that there is little evidence to prove that the basic speech course improves the student's self‐concept as a speaker. Future research should consider the factors of: (1) general tendency of self‐concept to change, (2) differences betwen male and female self‐concept, (3) individual differences in direction of change, (4) effects of reward, and, (5) possible variability among measures of self‐concept.
The enduring value of Gánti's chemoton model and life criteria: Heuristic pursuit of exact theoretical biology.

Abstract Ganti׳s chemoton model of the minimal chemical organization of living systems and life criteria for the living state and a living world are characterized. It is argued that these are better interpreted as part of a heuristic pursuit of an exact theoretical biology than as a “definition of life.” Several problems with efforts to define life are discussed. Clarifying the proper use of Ganti׳s ideas to serve constructive engineering idealizations helps to show their enduring value.