cssi/SciSciGPT-SciSciNet huggingface dataset:
Homeostatic role of heterosynaptic plasticity: models and experiments.

Homosynaptic Hebbian-type plasticity provides a cellular mechanism of learning and refinement of connectivity during development in a variety of biological systems. In this review we argue that a complimentary form of plasticity - heterosynaptic plasticity - represents a necessary cellular component for homeostatic regulation of synaptic weights and neuronal activity. The required properties of a homeostatic mechanism which acutely constrains the runaway dynamics imposed by Hebbian associative plasticity have been well-articulated by theoretical and modeling studies. Such mechanism(s) should robustly support the stability of operation of neuronal networks and synaptic competition, include changes at non-active synapses, and operate on a similar time scale to Hebbian-type plasticity. The experimentally observed properties of heterosynaptic plasticity have introduced it as a strong candidate to fulfill this homeostatic role. Subsequent modeling studies which incorporate heterosynaptic plasticity into model neurons with Hebbian synapses (utilizing an STDP learning rule) have confirmed its ability to robustly provide stability and competition. In contrast, properties of homeostatic synaptic scaling, which is triggered by extreme and long lasting (hours and days) changes of neuronal activity, do not fit two crucial requirements for a hypothetical homeostatic mechanism needed to provide stability of operation in the face of on-going synaptic changes driven by Hebbian-type learning rules. Both the trigger and the time scale of homeostatic synaptic scaling are fundamentally different from those of the Hebbian-type plasticity. We conclude that heterosynaptic plasticity, which is triggered by the same episodes of strong postsynaptic activity and operates on the same time scale as Hebbian-type associative plasticity, is ideally suited to serve homeostatic role during on-going synaptic plasticity.
Personal versus professional values in social work: A methodological note

Empirical studies of the values of the social work profession typically have focused on the personal values of social workers. This study is a pretest of a research design that distinguishes between the personal values of social workers and their perceptions of the values of the social work profession. The findings indicate that both the personal values of social workers and their perceptions of the values of the profession are distinguishable from the values of a sample of U.S. adults, but in different ways. The authors conclude that the values of the profession are accessible to empirical research and propose a research methodology.
Co-authorship, rational Erdős numbers, and resistance distances in graphs

The Erdős number (EN) for collaborative papers among mathematicians was defined as indicating the topological distance in the graph depicting the co-authorship relations, i. e., EN = 1 for all co-authors of Paul Erdős; EN = 2 for their co-authors who did not publish jointly with Erdős; etc. A refinement of this notion uses resistance distances leading to rational Erdős numbers (REN), which (as indicated by their name) are rational numbers. For acyclic graphs, EN = REN, but for graphs with circuits these numbers differ. Further refinements are possible using weighted edges in the co-authorship graph according to the number of jointly authored papers.
Chronic active gastritis due to Helicobacter pylori in immunized gnotobiotic piglets

In gnotobiotic piglets, parenteral vaccination with formalin-killed Helicobacter pylori and oral vaccination with live bacteria induced H. pylori-specific serum immunoglobulins G, M, and A. Vaccination reduced but did not prevent infection by subsequent challenge with viable H. pylori. Oral vaccination with killed bacteria was less effective in inducing serum antibody and had no effect on bacterial colonization. Immunization status influenced the histologic response of piglets to challenge by H. pylori. Lymphoplasmacytic gastritis was more severe in parenterally vaccinated piglets than in the other groups. In addition, neutrophilic infiltrates and neutrophilic gland abscesses in the gastric mucosa were present in 5 of 7 parenterally immunized piglets, none of the orally immunized piglets, and only 1 of 8 infected nonimmune control piglets. Furthermore, there was a positive correlation between immunoglobulin G, M, and A titer at challenge and severity of both neutrophilic and lymphocytic inflammation. These results suggest that although vaccination does not prevent infection by H. pylori, infection of an immune host leads to increased severity and activity of gastritis.
Drug Binding of Ophthalmic Viscoelastic Agents

• When viscoelastic agents that contain hyaluronate sodium are used during anterior segment surgical procedures, it is common for some of the material to remain intraocularly after the surgery is completed. A variety of drugs, used intracamerally or topically following surgery, are also present. These drugs may be bound to the polyanionic hyaluronate molecule. This occurrence may cause drug alterations in therapeutic effectiveness, pharmacokinetics, and toxicity. To investigate the possibility for drug-viscoelastic agent adsorption, in vitro drug-binding studies were performed on three commercial viscoelastic agents; undiluted aliquots of Amvisc, Healon, or Viscoat were mixed with radiolabeled d-threo-chloramphenicol, dexamethasone, l-epinephrine, or pilocarpine hydrochloride, placed in dialysis membranes, and dialyzed for 24 hours against an isotonic phosphate buffer. The calculated drug binding by a viscoelastic agent ranged from 0% to 1.5%. These extremely low values for in vitro drug uptake by viscoelastic agents made it unlikely that any significant drug-viscoelastic agent interaction would occur in the postoperative eye.
Efficient population transfer in a multilevel system using diverging laser beams

We investigate a three-step population scheme to efficiently transfer atoms to a particular metastable state of atomic dysprosium, and present evidence of adiabatic passage in the first step. This scheme will be employed in an ongoing search for parity nonconservation (PNC) in dysprosium. In order to excite a large fraction of the transverse velocity distribution, laser beams with divergences matched to the atomic beam are applied in the first and second steps. The total efficiency of the population transfer is analyzed, and the implications for the PNC work are discussed.
Proton translocation and proline uptake associated with reduction of nitric oxide by denitrifying Paracoccus denitrificans.

Summary Minimum →H + /2e − ratios for both the NO→1/2N 2 O and NO→1/2N 2 reactions were about 3.7 with denitrifying Paracoccus denitrificans . These ratios are only slightly less than those obtained with other N-oxides similarly linked to the oxidation of endogenous substrate. Active transport of [ 14 C]L-proline was supported by the above two reactions of NO in denitrifying cells. NO failed to promote proline uptake with aerobically grown cells. The uncoupler, carbonyl cyanide m -chlorophenylhydrazone, abolished proline uptake and greatly diminished proton translocation with NO and other N-oxides. The results directly demonstrate for the first time that reduction of exogenous NO is energy yielding in a denitrifying bacterium.
Oxidative degradation of phenol–formaldehyde polycondensation initial degradation reactions

The initial degradation of phenol–formaldehyde polycondensates has been found to follow two distinct pathways. Oxidation of the dihydroxydiphenylmethane unit to substituted dihydroxybenzophenone and dihydroxybenzhydrol species has been observed and substantiated using model compounds to support the characteristic infrared spectral changes. The ingrowth of ketonic species has been evaluated kinetically on phenol–formaldehyde polymers which have been cured fully to remove residual methylol groups. The rate constants have been found to be a factor of 33 times slower than those observed earlier for partially cured resins having relatively large numbers of residual methylol groups present. The activation energy for the initial ketonic carbonyl was found to be 15.6 ± 3.9 kcal. This value compares favorably with other values obtained for phenolic oxidation. The potential oxidation of methylol groups to substituted salicylic acid moieties could not be substantiated spectrally. However, a polymer containing 2-methylol-p-cresol on oxidation gave a small quantity of 5-methylsalicylic acid, thus substantiating methylol oxidation in competition with the further curing reaction which produces new diphenylmethane linkages. The secondary oxidation resulting in chain scission can be separated on a time scale from oxidations of the methylol type. The present study therefore significantly extends the initial oxidative degradation chemistry of phenol–formaldehyde polycondensates.
A passive radio-frequency identification (RFID) gas sensor with self-correction against fluctuations of ambient temperature

Abstract Uncontrolled fluctuations of ambient temperature in the field typically greatly reduce accuracy of gas sensors. In this study, we developed an approach for the self-correction against fluctuations of ambient temperature of individual gas and vapor sensors. The main innovation of our work is in the temperature correction which is accomplished without the need for a separate uncoated reference sensor or a separate temperature sensor. Our sensors are resonant inductor–capacitor–resistor (LCR) transducers coated with sensing materials and operated as multivariable passive (battery-free) radio-frequency identification (RFID) sensors. Using our developed approach, we performed quantitation of an exemplary vapor over the temperature range from 25 to 40 °C. This technical solution will be attractive in numerous applications where temperature stabilization of a gas sensor or addition of auxiliary temperature or uncoated reference sensors is prohibitive.
Generalized Tonic-Clonic Status Epilepticus in a Child with Cat-Scratch Disease and Encephalopathy

Cat-scratch disease occasionally can be associated with encephalopathy and present as status epilepticus. However, the majority of these patients recover without sequelae, as shown by our patient and previous reports. Cat-scratch disease with encephalopathy should be considered in the differential diagnosis of status epilepticus in children.
Aggregatibacter actinomycetemcomitans leukotoxin is post-translationally modified by addition of either saturated or hydroxylated fatty acyl chains

Aggregatibacter actinomycetemcomitans, a common inhabitant of the human upper aerodigestive tract, produces a repeat in toxin (RTX), leukotoxin (LtxA). The LtxA is transcribed as a 114-kDa inactive protoxin with activation being achieved by attachment of short chain fatty acyl groups to internal lysine residues. Methyl esters of LtxA that were isolated from A. actinomycetemcomitans strains JP2 and HK1651 and subjected to gas chromatography/mass spectrometry contained palmitoyl (C16:0, 27–29%) and palmitolyl (C16:1 cis Δ9, 43–44%) fatty acyl groups with smaller quantities of myristic (C14:0, 14%) and stearic (C18:0, 12–14%) fatty acids. Liquid chromatography/mass spectrometry of tryptic peptides from acylated and unacylated recombinant LtxA confirmed that Lys562 and Lys687 are the sites of acyl group attachment. During analysis of recombinant LtxA peptides, we observed peptide spectra that were not observed as part of the RTX acylation schemes of either Escherichia coli α-hemolysin or Bordetella pertussis cyclolysin. Mass calculations of these spectra suggested that LtxA was also modified by the addition of monohydroxylated forms of C14 and C16 acyl groups. Multiple reaction monitoring mass spectrometry identified hydroxymyristic and hydroxypalmitic acids in wild-type LtxA methyl esters. Single or tandem replacement of Lys562 and Lys687 with Arg blocks acylation, resulting in a >75% decrease in cytotoxicity when compared with wild-type toxin, suggesting that these posttranslational modifications are playing a critical role in LtxA-mediated target cell cytotoxicity.
Sequential chemical/biological oxidation of chlorendic acid

Chlorendic acid, a fire retardant, was subjected to sequential chemical/biological oxidation. Degradation of chlorendic acid was achieved by ozonation with chlorinated and non-chlorinated by-product production. The destruction of chlorendic acid and by-product distribution was a function of ozone contact time. After 450 min of ozonation, chlorendic acid and TOC removal percentages equaled 98% and 62.5%, respectively. When subject to 210 min of UV oxidation, chlorendic acid and TOC removal equaled 70 and 31%, respectively. With combined ozone/UV, near complete removal of chlorendic acid and TOC was achieved in 90 and 120 min, respectively. In biodegradation testing, chlorendic acid was not degradable. Biodegradation efficiency (DOC removal) of chlorendic acid ozonation by-products was a function of ozone contact time and approached 80%. Chlorendic acid UV oxidation products (210 min contact time) were poorly biodegraded. Ozone/UV oxidation products (40 min contact time) from chlorendic acid achieved 89% biodegradation. Biodegradation rates of chlorendic acid chemical oxidation by-products also were assessed. Based on the computed biokinetic values of biodegradation rates for the chemical oxidation products of chlorendic acid are sufficiently high to enable use of existing biological process infrastructure for treatment of chemical oxidation products.
Forced plume characteristics

This paper describes an investigation of turbulent forced plumes generated by the steady release of mass, momentum and buoyancy from a finite source in a uniform environment. The entrainment coefficient assumption has been made; however a variable coefficient has been used so that the characteristics of the transition from jet to plume behaviour can be presented more clearly. A modified Boussinesq approximation has been made which corrects for the effect of density variations in the mass and momentum fluxes. The treatment reveals that the characteristics of forced plumes can best be discussed by reference to the Froude number. For all cases of forced plumes (except a pure jet) the Froude number approaches a particular constant value as the height increases. DOI: 10.1111/j.2153-3490.1977.tb00758.x
Association of “Macho Man” Sexual Attitudes and Behavioral Risks in Urban Adolescents

We examined whether sexual attitudes of adolescents were related to their self-reported sexual risk behavior by analyzing survey data from 1,052 boys and girls aged 14 to 17 years from a low income, urban community. Sexual behavior norms that may increase sexually transmitted infection/HIV risks in youth were sanctioned more by males and by sexually experienced youth, but their attitudes were unassociated with either their age or race/ethnicity. Endorsement was correlated with greater intention to have sexual intercourse among all youth. Among sexually experienced participants, it was associated with earlier sexual debut, more partners, and less intention to use condoms but not with the number of unprotected sexual episodes in the prior six months. Sexual attitudes of youth may conflict with initiation and maintenance of safer sex practices, making them vulnerable to HIV and other sexually transmitted infections. Risk reduction interventions for adolescents should address this.
Minority charge storage characteristics of HBTs in saturation

Abstract An analytical model is developed to study the minority charge storage characteristics of heterojunction bipolar transistors in saturation. The model is used to compare the performance of single and double heterojunction bipolar transistors with both emitter-up and emitter-down configurations. It is shown that for the emitter-up structure a DHBT performs better than SHBT, while for the emitter-down structure the reverse holds true. It is also argued that best I 2 L performance may be obtained using a DHBT with a “weak” collector-base heterojunction.
Multi-detector computed tomography of an aortic dissection in a cat

Contrast enhanced, multi-detector computed tomography (MDCT) is a useful diagnostic imaging modality that has become increasingly available in veterinary medicine. Multi-planar and three-dimensional reconstructions allow accurate and comprehensive assessment of cardiac and vascular lesions with short image acquisition times. ECG-gated, contrast enhanced MDCT was used to assess the lesion extent and therapeutic options in a case of aortic dissection diagnosed in a hypertensive cat.
Poster abstract: A beamforming method for multiple source DOA estimation, spectrum separation and localization from field data

In this abstract, we present a beamforming method for estimating the directions and locations of multiple sources and separating each source's spectrum from field data collected by a wireless acoustic sensor network. Each acoustic sensor is equipped with four microphones that receive acoustic signals in a time-synchronized manner. The difference in time-of-arrival of proximal signals depends on the source direction with respect to the geometry of the microphone array. We show that by using beamforming in the frequency domain, the locations and Direction-Of-Arrivals (DOAs) of multiple 3D sources may be estimated, and the source spectrum may be separated from the audio data spectra.
Assessing Research Impact: Semiquantitative Methods

Three types of semiquantitative methods used by the federal government in research impact assessment are presented. These include the classic retrospective method (Project Hindsight), another retro...
Deficient cellular cyclic AMP may causeboth cardiac and skeletal muscle dysfunction in heart failure

Deficient myocardial cyclic AMP concentrations contribute to abnormal Ca2+ handling and systolic and diastolic dysfunction in chronic heart failure (CHF). We tested the hypothesis that decreased cyclic AMP in skeletal muscle of animals with failure may contribute to the weakness and easy fatiguability also common in patients with CHF. We compared intracellular Ca2+ signaling and contractility in skeletal muscle preparations from rats 6 weeks after myocardial infarction-induced CHF versus sham-operated controls. Bundles of 100 to 200 cells were dissected from the extensor digitorum longus (EDL) muscle of control and CHF rats. Muscles from CHF rats exhibited depressed tension development compared with control muscles during twitches. Treatment with 2mM dibutyryl cyclic AMP returned tension and Ca2+ towards normal levels. There was no evidence of cellular atrophy in the CHF rats. In conclusion, EDL skeletal muscle from rats with CHF had intrinsic abnormalities in excitation-contraction coupling that could be reversed with cyclic AMP supplementation as previously reported for the heart. This suggests that deficient cyclic AMP levels may contribute to both cardiac and skeletal muscle dysfunction in CHF.
Personal communication systems-integration opportunities and trends

The opportunity for system integration that is presented by the trend towards personal communication products is examined. It is pointed out that the performance of the semiconductor industry will be key in achieving the cost, size, and performance necessary to satisfy the needs of business and the mass market. A range of semiconductor capabilities will be needed which raise interesting questions concerning system partitioning and the choice of technology. It is noted that the current adoption of digital standards in Europe, North America, and Japan represents the first step towards the personal communicator. However, one of the main enabling factors in achieving this goals, a very low-cost terminal, will be an evolution which will take place in parallel with the growth of systems. It is concluded that the rate at which this will be achieved will be a consequence of commonality of standard. >
Crack tip plasticity in single crystal UO2: Atomistic simulations

Abstract The fracture behavior of single crystal uranium dioxide under mode-I loading is studied using molecular dynamics simulations at room temperature. The initial cracks are introduced as elliptical notches on either {1 1 1} or {1 1 0} planes. Two crack tip shielding mechanisms, dislocation emission and metastable phase transformation are identified. Crack extension is observed for cracks residing on {1 1 1} plane only. The dislocations have a Burgers vector of 〈1 1 0〉/2 and glide on {1 0 0} planes. Two metastable phases, Rutile and Scrutinyite, are identified during the phase transformation, and their relative stability is confirmed by separate density-functional-theory calculations. Examination of stress field near the crack tips reveals that dislocation emission is not as an effective shielding mechanism as the phase transformation. The formation of new phases may effectively shield the crack if all phase interfaces formed near the crack tips are coherent, as in the case of cracks residing on {1 1 0} planes.
Influence of severity of ventricular dysfunction on hemodynamic responses to intravenously administered verapamil in ischemic heart disease

The effects of verapamil, 0.145 mg/kg body weight, administered intravenously in a bolus injection followed by 0.005 mg/kg per min, on cardiovascular hemodynamics and on ventricular ejection fraction, determined with gated cardiac blood pool scanning, were studted in 25 patients, 8 with acute myocardial infarction and 17 with symptomatic coronary artery disease who were undergoing diagnostic cardiac catheterization. The mean (± standard deviation) plasma verapamil level, determined with a gas liquid chromatographic technique utilizing a nitrogen detector, was 161 ± 47 ng/ml (n = 8) during steady state conditions of drug infusion. In 15 patients with stable coronary artery disease having a normal or moderately reduced ejection fraction, verapamil reduced mean arterial pressure (−16 percent, probability [p] < 0.001), systemic vascular resistance (−23 percent, p < 0.001), stroke work index (−13 percent, p < 0.02), with no significant change in pulmonary vascular resistance, ejection fraction or heart rate; cardiac index was increased (+11 percent, p < 0.001) as was the stroke volume index (+7 percent, p < 0.01) and mean capillary wedge pressure (+10 percent, p < 0.01). In the seven patients with uncomplicated infarction, there was no effect on ejection fraction, heart rate or pulmonary vascular resistance. There was a decrease in systemic vascular resistance (−22 percent, p < 0.01) and mean arterial pressure (−16 percent, p < 0.01) with an increase in cardiac index (+27 percent, p < 0.05), stroke volume index (+4 percent, p < 0.05) and mean capillary wedge pressure (+17 percent, p < 0.02). In three patients, one wlth acute infarction and two with coronary artery disease, having a severely reduced ejection fraction and elevated mean capillary wedge pressure (20 mm Hg or greater), mean arterial pressure decreased markedly with a fall in stroke volume index and an abrupt increase in the mean pulmonary capillary wedge pressure. These findings were associated with clinical evidence of heart failure and dyspnea. It is concluded that (1) in patients with cardiac disease having a mild to moderate decrease in left ventricular ejection fraction accompanied by a normal or mildly elevated mean pulmonary capillary wedge pressure, the intrinsic depressant effect of verapamil is offset almost entirely by its potent vasodilator proporties, but (2) in patients with a severely reduced ejection fraction and a high pulmonary capillary wedge pressure, the depressant effects of the compound become clinically apparent with sudden further increases in pulmonary capillary wedge pressure and a decrease in stroke volume and mean arterial pressure.
Effects of response force on conjugate rates

Abstract The effects of increased response-force on conjugate response rates were investigated by two procedures which required subjects to work to maintain the intensity of the audio and video channels of a continuously available filmed narration. In the first procedure nine normal boys responded via handswitches requiring 600 g of force to operate while another group of nine boys used handswitches requiring 3000 g of force. The high force group emitted significantly lower rates than the low force group. Added force also increased behavioral responsiveness to two deceleration contingencies. In the second procedure a single group of six learning disabled boys worked under two force conditions. Added force resulted in significant group differences on one of the arrangements of consequences. It also amplified the effect of the deceleration contingencies, and clarified differences in the consequential value of the two narrations. Increasing the response-force requirement heightens the sensitivity of a conjugate analysis of preferences.
A sequential pursuer-target assignment problem under external disturbances

In this paper we deal with the problem of a team of pursuers distributed in the plane subject to an environmental disturbance (e.g., wind). The objective of the pursuers is to intercept a moving target which is not affected by the presence of the disturbance. We solve this problem by assigning only one pursuer to chase the target at every instant of time, based on a Voronoi-like partition of the plane. During the pursuit, the pursuer assignment changes dynamically based on this partition. We present an algorithm to efficiently update this Voronoi-like partition on-line. Simulations are included to illustrate the theoretical results.
Responses of the Murine Myeloid Colony-Forming Cell to Ansamycin Antibiotics

The in vitro susceptibility of murine myeloid colony-forming cells to the antiproliferative activities of three ansamycin antibiotics was determined. These cells were found to be 10- to 40-fold more susceptible than the corresponding human ones.
Hydrogen production from methane and solar energy – Process evaluations and comparison studies

Three conventional and novel hydrogen and liquid fuel production schemes, i.e. steam methane reforming (SMR), solar SMR, and hybrid solar-redox processes are investigated in the current study. H2 (and liquid fuel) productivity, energy conversion efficiency, and associated CO2 emissions are evaluated based on a consistent set of process conditions and assumptions. The conventional SMR is estimated to be 68.7% efficient (HHV) with 90% CO2 capture. Integration of solar energy with methane in solar SMR and hybrid solar-redox processes is estimated to result in up to 85% reduction in life-cycle CO2 emission for hydrogen production as well as 99–122% methane to fuel conversion efficiency. Compared to the reforming-based schemes, the hybrid solar-redox process offers flexibility and 6.5–8% higher equivalent efficiency for liquid fuel and hydrogen co-production. While a number of operational parameters such as solar absorption efficiency, steam to methane ratio, operating pressure, and steam conversion can affect the process performances, solar energy integrated methane conversion processes have the potential to be efficient and environmentally friendly for hydrogen (and liquid fuel) production.
Mechanisms and advances in allergic diseases

There have been many attempts to explain the increases in the incidence of allergic diseases, including hay fever and allergic asthma, that have been documented worldwide in recent decades. Epidemiologic studies offer rich opportunities to uncover sometimes unexpected correlations between lifestyle, environmental exposures, temporal development of the immune system, and genetics. Examples include the differing prevalence of atopy, bronchial hyperresponsiveness, and asthma in East and West Germany around the time of reunification, which suggests that a "western lifestyle presents a greater risk for the development of allergic responses than the more traditionally suspected factor of outdoor air pollutant levels. Other epidemiologic studies suggest how infections may interface with an atopic patterning: Evidence from natural measles exposure and nonwheeze-inducing lower respiratory tract infections in young children implicate early childhood viral infections as protective against the development of atopy and airway allergic sensitivity, although in later life viral airway infections exacerbate asthma symptoms. These studies and others involving the scrutiny of lymphocyte subtypes in atopic individuals, notably T(H1) and T(H2) cells, are helping to formulate a theory of interdependence between the early development of the immune system, allergen exposure, and the diverse community of airway cells whose secretory products generate the final physiologic response pattern.
Fentanyl citrate analgesia during labor

Fentanyl citrate is a potent short-acting narcotic reported to cause less nausea and sedation than morphine or meperidine hydrochloride. The purpose of this prospective investigation was to determine whether a safe but adequate intrapartum dosing schedule is possible. A total of 137 women with uncomplicated term pregnancies were offered a standard intravenous dose (50 mcg or 100 mcg hourly as needed) of fentanyl citrate during active labor. Temporary analgesia and mild sedation were apparent in each case. The cumulative dose varied in accordance with maternal needs (mean, 140 ± 42 µg; range, 50 mcg to 600 µg). Apart from a brief decrease in fetal heart rate variability that lasted 30 minutes, no worrisome pattern was apparent from exposure to fentanyl citrate. Pediatric examinations were performed without knowledge of analgesic therapy on infants exposed to fentanyl citrate and those not exposed to analgesics. No differences were found in frequencies of newborn depressed respirations, low Apgar scores, or neurologic and adaptive capabilities at two hours and 24 hours postnatally. With the use of the described dosing schedule, fentanyl citrate was helpful during labor and did not cause immediate or prolonged hazards to the mother and unborn infant.
Advanced feature extraction in remote sensing using artificial intelligence and geographic information systems

Traditional computer-assisted image-analysis techniques in remote sensing lag well behind human abilities in terms of both speed and accuracy. A fundamental limitation of computer-assisted techniques is their inability to assimilate a variety of different data types leading to an interpretation in a manner similar to human image interpretation. Expert systems and computer-vision techniques are proposed as a potential solution to these limitations. Some aspects of human expertise in image analysis may be codified into expert systems. Image understanding and symbolic reasoning provide a means of assimilating spatial information and spatial reasoning into the analysis procedure. Knowledge-based image-analysis systems incorporate many of these concepts and have been implemented for some well defined problem domains. Geographic information systems represent an excellent environment for this type of analysis, providing both analytic tools and contextual information to the analysis procedure.
Virtual teams: a review of current literature and directions for future research

Information technology is providing the infrastructure necessary to support the development of new organizational forms. Virtual teams represent one such organizational form, one that could revolutionize the workplace and provide organizations with unprecedented levels of flexibility and responsiveness. As the technological infrastructure necessary to support virtual teams is now readily available, further research on the range of issues surrounding virtual teams is required if we are to learn how to manage them effectively. While the findings of team research in the traditional environment may provide useful pointers, the idiosyncratic structural and contextual issues surrounding virtual teams call for specific research attention.This article provides a review of previously published work and reports on the findings from early virtual team research in an effort to take stock of the current state of the art. The review is organized around the input - process - output model and categorizes the literature into issues pertaining to inputs, socio-emotional processes, task processes, and outputs. Building on this review we critically evaluate virtual team research and develop research questions that can guide future inquiry in this fertile are of inquiry.
Effects of histrionicotoxin on the chemosensitive and electrical properties of skeletal muscle.

Abstract Histrionicotoxin (HTX), a spiropiperidine alkaloid from the Colombian frog, Dendrobates histrionicus , has a variety of effects on the function of mammalian and amphibian nerve-muscle preparations. At a concentration of 70 × 10 −6 m , HTX blocks indirectly elicited muscle twitches in the mouse phrenic nerve-diaphragm preparation within 20 min, while potentiating directly elicited twitches. Resting membrane potential and passive electrical properties are little affected by the drug. HTX prolongs the falling phase of the action potential and blocks delayed rectification, indicating that the potassium conductance is suppressed. Endplate potentials are also blocked by the toxin, and the onset of this blockade is dependent on the frequency of stimulation. Similarly, HTX decreases the sensitivity of denervated mammalian skeletal muscles to repetitive applications of acetylcholine, the degree of blockade also being dependent on the rate and duration of iontophoretic application of acetylcholine. All effects of HTX are reversed by washing the muscle. HTX does not prevent the irreversible effects of an acetylcholine antagonist, α-bungarotoxin, in the mouse phrenic nerve-diaphragm preparation. It is suggested that HTX acts on the ionic conductance modulator of the acetylcholine receptor in a manner similar to its semisynthetic derivative perhydrohistrionicotoxin.
Catalysis of coal conversion at mild temperatures

Abstract Many materials have been used or tested as catalysts for the direct conversion of coal to liquids. However, the factors which determine whether a particular substance will be an excellent, fair or poor catalyst, or an inhibitor, are still not understood. Most of the catalyst studies have been of empirical nature and neither the specific catalytic mechanisms nor the exact forms responsible for the catalytic effects observed have been elucidated. In studies on the catalytic action of Lewis acids for the liquefaction of coal, many properties of these materials were correlated. After testing more than eighty catalysts, only one property was found to directly correlate with the yield of liquefaction products in coal conversion experiments. This property was found to be the electronic softness of the Lewis acids studied. Results from mild liquefaction experiments on bituminous coal have been obtained and give insight into the reactions taking place and the moieties involved in most of the liquefaction reactions.
Regional Trade and Production Blocs in a Global Industry: Towards a Comparative Framework for Research:

While apparel manufacturing is often considered the quintessential global industry, the regional dimension of trade and production in the textile and clothing sector is less widely noted. In this paper I discuss two macroregional production blocs: North America (defined as the United States, Mexico, and the Caribbean Basin countries) and Greater Europe [which includes the European Union (EU), Central and Eastern Europe, Turkey, and North Africa]. Analyzing what opportunities regionalization might provide is particularly relevant given China's increasing dominance of both the EU and US import markets in the post-Multifibre Arrangement period. Drawing on the global commodity chains literature, I discuss three dimensions around which cross-regional comparative research on the European and North American apparel sectors can be organized: (1) production model; (2) institutional context; and (3) development outcomes. Several similarities between these production blocs are noted, particularly with regard to the ...
Non-linear finite element dynamic analysis of two-dimensional concrete structures

Abstract This paper presents a numerical procedure for predicting the non-linear dynamic response of plane and axisymmetric reinforced concrete structures. Isoparametric elements with special embedded axial members are used to discretize concrete and steel in space. A summary of a rate and history dependent constitutive model for progressive failure analysis of concrete is given in which the compression behaviour is modelled as a strain rate sensitive elasto-viscoplastic material and in tension as strain rate dependent linear elastic strain softening material. The different rales governing the pre-failure and post-failure behaviour in compression and tension are developed in which the strain rate dependency is included. Steel is modelled as a strain rate dependent uniaxial elasto-viscoplastic material. Explicit central difference scheme in conjunction with an energy balance check is employed for time integration of equations of motion. A computer program for linear and non-linear dynamic analysis of concrete structures is described. Finally, some numerical applications are presented.
Damage Accumulation Model of Prosthetic Heart Valves in Forward and Reverse Flow Phases

A highly resolved 3D geometry of a bileflet mechanical heart valve (MHV) was constructed to study the contribution of the forward and regurgitant flow phases to platelet damage. Platelet stress accumulation during repetitive passages past the valve was calculated using a damage accumulation model in pertinent trajectories. Additionally a discrete particles dynamics (DPD) multiscale modeling approach, which widely departs from the traditional continuum approach, was applied to this MHV geometry. It generated viscous blood flow velocity distributions, and is envisioned to further facilitate multiscale simulations of flow induced thrombogenicity in blood recirculating devices.Copyright © 2008 by ASME
The impact of differences in methodology and population characteristics on the prevalence of hypertension in US adults in 1976-1980 and 1999-2002.

Background Results from the National Health and Nutrition Examination Survey (NHANES) indicate that hypertension prevalence declined by 9% points from 34% in 1976-1980 to 25% in 1999-2002 in adults 20-74 years. The purpose of this study was to estimate the impact on hypertension prevalence of measurement error and selected risk factors. Methods Using cross-sectional survey data from NHANES, we estimated the effect on hypertension of incorrect blood pressure (BP) cuff size and zero end-digit preference and the effect of changes in the distribution of age, body mass index (BMI), sex, race-ethnicity, smoking, and education. The analytic sample of persons 20-74 years consisted of 11,563 from 1976-1980 and 7,901 from 1999-2002 NHANES. Covariate-adjusted prevalences were calculated using log-linear regression models to produce predictive margins. Results After adjustment to age, BMI, sex, race-ethnicity, smoking, and education, the prevalence difference became higher, changing from -9% (95% confidence interval (CI): -11, -6) to -14% (95 CI: -17, -11). After adjustment to these risk factors and correction for measurement error the prevalence difference was -9% (95 CI: -11, -6). Conclusions Measurement error, mainly from cuff size differences, inflated the temporal decline in hypertension prevalence. The results indicate that age, sex, race-ethnicity, smoking, or education did not fully explain the lower prevalence of measured hypertension in all BMI groups and suggest that a change in some unmeasured factor or factors contributed to the decline.
Dispersion studies of the 22 GHz water vapor line shape II. Instrumental correction

Anomalies in the resonance dispersion of the pressure-broadened water vapor line at a frequency of 22.235 GHz are resolved. The pressure-scanning differential-refraction spectrometer gives rise to a signal enhancement as the line center moves within the width of the dispersion discriminator. Resonance absorption prevents the frequency of peak transmitted power from coinciding with the resonance condition of zero phase. The results reported for the 23.6 GHz rotational line of ethylene oxide show a Lorentzian molecular line shape.
the emergence of the northern Ojibwa: social and economic consequences1

During the historic period, the Ojibwa expanded over an area considerably larger than that which they had occupied at contact and, in the process, grew in numbers. Those groups which migrated into the area north and west of Lake Superior, the Northern Ojibwa, segmented into smaller entities, as they adapted to the fur trade and a new environmental setting. The original patrilineal clan-totem groups split off into subgroups, which, in time, often became widely separated. As the environment became depleted of large game and beaver, and the Ojibwa became dependent on European commodities for survival, these clan-named groups further fragmented into families during the colder months to hunt and trap. By the nineteenth century, trade and ecological conditions had made the former clan system dysfunctional. The major process in the early historic dispersal, one which may have predated contact, was segmentation along lineage lines.
Twelve-lead electrocardiographic characteristics of the aortic cusp region guided by intracardiac echocardiography and electroanatomic mapping.

Background The most common site of origin of idiopathic ventricular tachycardia (VT) is the right ventricular outflow tract. Idiopathic VT also can arise from the left ventricular outflow tract and the surrounding structures. Morphologic descriptions of 12-lead ECG characteristics of the aortic cusp region are limited. Objective The purpose of this study was to define unique ECG characteristics of the aortic cusp region by performing a systematic analysis of pacemapping of this region in patients with structurally normal hearts. Methods A combination of electroanatomic mapping, intracardiac echocardiography, and fluoroscopic guidance was used to study a total of 30 patients with structurally normal hearts undergoing left-sided ablation procedures. Each of the aortic valve cusps and the aortomitral continuity were paced at threshold and analyzed offline to determine unique ECG characteristics. Results Pacing from the left coronary cusp typically produced a multiphasic QRS morphology consistent with an M or W pattern in lead V 1 with a precordial transition (R>S) no later than V 2 . Pacing from the right coronary cusp typically resulted in a left bundle-type pattern with a broad small R wave in V 2 and a precordial transition generally at V 3 . Pacing from the aortomitral continuity resulted in a qR pattern that was not observed anywhere else in the left ventricular outflow tract. When comparing the right coronary cusp and left coronary cusp, the precordial transition was earlier in the left coronary cusp than in the right coronary cusp. Pacing the noncoronary cusp uniformly resulted in atrial capture. Conclusion When considering ablation of idiopathic VT, the aortic cusps and aortomitral continuity must be considered as possible foci. The 12-lead ECG, a readily and easily obtainable source of information, has useful characteristics for differentiating VTs arising from the cusp region.
Calcium-dependent atrial slow action potentials generated with phosphatidic acid or phospholipase D

Phosphatidic acid (PA) formed following phosphatidylinositol hydrolysis has been proposed as a necessary step in receptor-mediated Ca2+ flux. This study demonstrates that PA generates Ca2+-dependent slow action potentials (APs) in rat atrium partially depolarized with 22 mM K+. The slow response was not due to release of endogenous catecholamines or prostaglandin formation since propranolol and indomethacin failed to attenuate the PA-induced slow AP in normal and reserpinzed rats. PA-induced slow APs demonstrated Ca2+-dependence such that increasing [Ca2+]o from 0.5 to 5.0 mM caused the amplitude of the slow AP to rise linearly with the logarithm of [Ca2+]o. Phospholipase D (PLD) but not phospholipase C, was able to induce a slow AP, possibly through PA formation. Adenosine attenuated the PA and PLD-induced slow response and aminophylline reversed these effects. The observation that PA and PLD generate Ca2+-dependent slow APs in depolarized rat atrium supports a role for PA mediating Ca2+ influx.
A mechanistic model of GPS collar location data: Implications for analysis and bias mitigation

Abstract Global positioning system (GPS) collars have revolutionized the collection of animal location data; however, it is well-recognized that considerable bias can be present in these data due to habitat or behavior-induced obstruction of satellite signals resulting in inaccurate or missing locations. To date, no explicit theoretical framework of GPS fix acquisition specific to animal telemetry has been presented, and studies make differing assumptions regarding factors influencing GPS fix acquisition and how these data should be analyzed. Inappropriate statistical models have been used, interaction effects have been misunderstood, and the implementation of bias mitigation techniques has been problematic. Herein we outline current conceptual and analytical problems in the GPS animal telemetry literature, and subsequently present a theoretical model-based framework for GPS fix acquisition that clarifies the single and interactive effects of habitat and behavioral obstruction, fix interval, and collar model on GPS collar performance. By recognizing that GPS fix acquisition is a Bernoulli process, it becomes apparent that all forms of obstruction inherently interact with each other, making generalizations across study areas, study species, and collar models problematic. Stationary collar tests to determine the probability of fix acquisition (PFA), location accuracy, and the response to sources of obstruction are thus of limited applicability to animal-deployed collars. Bias mitigation techniques that extrapolate PFA models across samples, especially those using stationary collar tests to correct animal-deployed collars, are theoretically unsound. It is also demonstrated that nonlinearities in the relationships between sources of obstruction and PFA complicate PFA modeling with limited data and that even slight model misspecification can lead to considerable errors in correction factors, especially when using inverse weighting to mitigate bias. By emphasizing the importance of GPS collar sensitivity and ephemeris retention, the theoretical framework predicts that newer, more sensitive GPS collars will be less severely biased by sources of obstruction than reported for the older, less sensitive collars that have been used in the majority of GPS performance studies to date and we expect this trend to continue. This heuristic modeling exercise should be of value to researchers planning and analyzing studies using GPS collars and it also establishes a starting point for future theoretical investigations into GPS collar performance and bias mitigation.
Focal seizure and cerebral contrast retention after cardiac catheterization

Although rare, ionic and nonionic contrast-induced seizures occur as a complication of enhanced cranial computed tomography for both adults and children. However, contrast-induced seizures after cardiac catheterization has only been reported in adults. This report describes an 18-month-old male who developed a new-onset focal seizure 12 hours after cardiac catheterization. Unenhanced cranial computed tomography 1 hour after the seizure demonstrated general cerebral edema and unilateral focal cerebral contrast retention with sparing of the area supplied by the middle cerebral artery. The contrast was reabsorbed from the subarachnoid space over a 48-hour period, the cerebral edema resolved over several days, and the child returned to his baseline state 4 days after the seizure episode. This study documents the evolution of computed tomographic findings after contrast-induced seizures in a child. Contrast toxicity should be considered in any case of a new-onset neurologic deficit arising after angiography or enhanced computed tomography.