Use of cluster and principal component analyses to profile areas in California where ground water has been contaminated by pesticides

An empirical approach to profiling areas of ground water contamination by pesticides was devised that did not rely upon determining the level of vulnerability between land areas and that did not assume any particular pathway for ground water contamination. Climatic and soil data were obtained for 1-square mile sections of land in California where pesticide residues had been found in well water samples and the detection was attributed to legal agricultural applications. These sections were designated as known contaminated (KC) sections. Climate and soil data were also obtained for sections which lacked either well sampling data or a positive pesticide detection. These sections were designated as candidate sections. Statistical procedures were used to cluster groups of KC sections first with respect to climate characteristics and then with respect to soil characteristics. Principal components analysis (PCA) was used to construct a statistical profile of soil variables for each cluster of KC sections. A method based on the PCA was developed to compare the similarity of soil profiles derived for each KC section cluster to individual candidate sections. Since the profiling scheme was based only on data from KC sections, candidate sections that did not match any KC cluster profile could only be considered dissimilar to contaminated sections, receiving a status of not-classified. This profiling method is flexible and it can be revised to incorporate updated well sampling information.

Differential modulation of chemical and electrical components of mixed synapses in the lobster stomatogastric ganglion

1. Two pairs of neurons in the pyloric network of the spiny lobster, Panulirus interruptus, communicate through mixed graded chemical and rectifying electrical synapses. The anterior burster (AB) chemically inhibits and is electrically coupled to the ventricular dilator (VD); the lateral pyloric (LP) and pyloric (PY) neurons show reciprocal chemical inhibition and electrical coupling. We examined the effects of dopamine (DA), serotonin (5HT) and octopamine (Oct) on these mixed synapses to determine the plasticity possible with opposing modes of synaptic interaction. 2. Dopamine increased net inhibition at all three pyloric mixed synapses by both reducing electrical coupling and increasing chemical inhibition. This reversed the sign of the net synaptic interaction when electrotonic coupling dominated some mixed synapses, and activated silent chemical components of other mixed synapses. 3. Serotonin weakly enhanced LP-->PY net inhibition, by reducing electrical coupling without altering chemical inhibition. Serotonin reduced AB-->VD electrical coupling, but variability in its effect on the chemical component made the net effect non-significant. 4. Octopamine enhanced LP-->PY and PY-->LP net inhibition by enhancing the chemical inhibitory component without altering electrical coupling. 5. Differential modulation of chemical and electrical components of mixed synapses markedly changes the net synaptic interactions. This contributes to the flexible outputs that modulators evoke from anatomically defined neural networks.

Tunable fast-pulse amplification based on the timing of photodissociation

A new type of ultrafast laser amplifier is proposed based on timed interruption of photodissociation. The principle is demonstrated with time-dependent quantum calculations for the molecule CsCl. This disomer and disoplex laser can potentially exhibit a very large tuning range for amplification of fast pulses.

Dopamine induces sign reversal at mixed chemical-electrical synapses

A mixed chemical/electrical synapse can generate variable output when the strength of each synaptic component is modulated. At mixed synapses of the lobster pyloric network, the chemical component is inhibitory. Without neuromodulation, the chemical component is weak or absent and the electrical component often dominates. Dopamine reverses the sign of these mixed synaptic interactions by a reduction in the strength of electrical coupling and an enhancement of chemical inhibition, including activation of silent chemical synapses. Sign reversal at mixed synapses by neuromodulators may contribute to functional rewiring of neural networks.

Probing Chemical Reactions: Evidence for Exploration of an Excited Potential Energy Surface at Thermal Energies

The reaction K + NaBr --> KBr + Na is probed during the reactive collision by a continuous wave laser tuned to frequencies not resonant with excitation in either reagents or products. Transient [K..Br..Na] absorbs a laser photon giving [K..Br..Na](*), which can decompose to Na(*) + KBr. Emission from excited Na(*) at the sodium D lines provides direct evidence of laser absorption during the reaction. Different excitation spectra were observed, depending on which sodium D line was monitored. This difference is explicable if, in the absence of the laser, the reaction flux partially bifurcates to a second potential energy surface during the reaction.

Amine modulation of electrical coupling in the pyloric network of the lobster stomatogastric ganglion

1. The neurons of the pyloric network of the lobster (Panulirus interruptus) stomatogastric ganglion organize their rhythmic motor output using both chemical and electrical synapses. The 6 electrical synapses within this network help set the firing phases of the pyloric neurons during each rhythmic cycle. We examined the modulatory effects of the amines dopamine (DA), serotonin (5HT) and octopamine (Oct) on coupling at all the electrical synapses of the pyloric network. 2. Electrical coupling within the pacemaker group [anterior burster (AB) to pyloric dilator (PD), and PD-PD] was non-rectifying, while coupling at the other electrical synapses [AB to ventral dilator (VD), PD-VD, lateral pyloric (LP) to pyloric (PY), and PY-PY] was rectifying. 3. Dopamine decreased or increased the coupling strength of all the pyloric electrical synapses: the sign of the effect depended upon which neuron was the target of current injection. For example, DA decreased AB-->PD coupling (i.e., when current was injected into the AB) but increased coupling in the other direction, PD-->AB. Dopamine decreased AB to VD coupling when current was injected into either neuron. Serotonin also had mixed effects; it enhanced PD-->AB coupling but decreased AB to VD and PD to VD coupling in both directions. Octopamine's only effect was to reduce PD-->VD coupling. 4. Dopamine increased the input resistance of the AB neuron but decreased the input resistance of the PD and VD neurons. Serotonin reduced the input resistance of the VD and PY neurons, while Oct did not significantly change the input resistance of any pyloric neuron. 5. The characteristic modulation of electrical coupling by each amine may contribute to the unique motor pattern that DA, 5HT and Oct each elicit from the pyloric motor network.

Costs and resource utilization for the treatment of incomplete abortion in Kenya and Mexico

In much of the developing world, sharp curettage (SC) is the most commonly used technique for treating incomplete abortion. The procedure is usually performed in a hospital setting where physicians and operating theatres are available; it often involves light to heavy sedation for pain control and an overnight hospital stay for patient recuperation and monitoring. This study examined the hypothesis that use of manual vacuum aspiration (MVA)--a variation of vacuum aspiration (VA)--would be less costly than SC and thus be advantageous to healthcare systems with limited resources. The purpose of the study was to identify and, where possible, to explain the factors that contributed to cost differences between MVA and SC for treatment of incomplete abortion. To achieve this objective, researchers observed patient management and documented resource use at hospital sites in Kenya and Mexico. The results of the study support the researchers' hypothesis that, in most cases, treatment with MVA required a shorter patient stay and fewer hospital resources than SC, as the two techniques were practiced at the various study sites. The policy decision to adopt MVA, supported by procurement of instruments and incorporation of training in its use, is the basic prerequisite to achieving reduced levels of resource use. The study results also suggest that the full advantages of MVA can be realized only if it is introduced in conjunction with certain changes in patient management, such as offering outpatient treatment for incomplete abortion.

Contraception and abortion in Romania

After the downfall of the Ceausescu regime in December, 1989, the new Government of Romania abolished the law that prohibited abortions on request. Subsequently, the rate of legally induced abortions increased significantly while the rate of maternal mortality declined dramatically. Despite the large number of women who request induced abortions, most women and gynaecologists say that they would prefer to prevent unwanted pregnancies through the use of modern contraception. In this paper we examine factors that contribute to the disparity between women's desire to use modern contraception to prevent unwanted pregnancies and their practice of having induced abortions to prevent unwanted births. The results show that women (and suggest that men) need a wide choice of dependably available high-quality contraceptives; they need to be able to obtain information, counselling, and methods from a wide range of sources/health-care providers; both women's and men's perceptions about, and use of, modern contraception could be positively affected through sexual education started in secondary school; and, to reduce repeat abortions, women's post-abortion family-planning needs must not be neglected.

Effective shelf-life of prepared sodium hypochlorite solution

Although the tissue solvent and bactericidal properties of sodium hypochlorite are well known, the effective shelf-life of prepared sodium hypochlorite solutions is not known. The stability of sodium hypochlorite is adversely affected by exposure to high temperature, light, air, and the presence of organic and inorganic contaminants. The purpose of this study was to investigate the variables of storage conditions and time on the tissue-dissolving capacity of three different concentrations of sodium hypochlorite. Fresh frozen human umbilical cord was used as the tissue sample for this experiment. Tissue samples were dissolved at time intervals ranging from 1 day to 10 wk in 5.25%, 2.62%, and 1.0% solutions of sodium hypochlorite. The tissue-dissolving ability of 5.25% sodium hypochlorite remains stable for at least 10 wk. The tissue-dissolving ability of 2.62% and 1.0% sodium hypochlorite remains relatively stable for 1 wk after mixing, then exhibits a significant decrease in tissue-dissolving ability at 2 wk and beyond.

Viral pathogens of acute lower respiratory infections in pre-school Nigerian children and clinical implications of multiple microbial identifications

In a prospective study of acute lower respiratory infections (ALRI), at the University College Hospital, UCH, Ibadan, 35 viral pathogens were identified by immunofluorescence (IF) techniques from 24 (68.6%) respiratory specimens from 35 hospitalised pre-school children. The respiratory diagnoses comprised croup, bronchiolitis, pneumonia and pleural effusion. The viral identifications comprised 14 (40.0%) of parainfluenza virus type 3, 10 (28.6%) of respiratory syncytial virus (RSV), 5 (14.3%) of influenza virus type A, 4 (11.4%) of parainfluenza virus type 1 and 2 (5.7%) of influenza virus type B. Two or more viral agents were identified in as many as 10 (41.7%) of the 24 IF positive secretions, 8 (80.0%) of which were obtained from children with features of protein energy malnutrition. Twenty subjects had both virological and bacteriological analyses, in 8 (40.0%) of whom co-existing bacteraemia was identified. Four (50.0%) of these blood culture positive subjects, also had features of overt malnutrition. Neither the age nor the sex was significantly related to the viral identifications (P > 0.81 & 0.35 respectively). Similarly, the final respiratory diagnoses were not significantly related to the viral identifications despite the seemingly suggestive relationship between a diagnosis of croup and parainfluenza identifications as well as that between pneumonia and RSV/parainfluenza type 3 identifications. It is concluded that the high proportion of positive viral identifications is a pointer to the importance of viruses as possible primary etiological agents of ALRI in countries of the West African sub-region and perhaps in developing countries of other tropical subregions. The multiplicity of microbial identifications (viruses and bacteria), seen in malnourished children, may explain the clinical severity of ALRI in the same group of children. The usefulness of IF as a rapid diagnostic tool, as well as the potential implications of our findings on ARI control in developing countries, are discussed.

A new sampling technique that allows quantitative fit testing by using the employee's own respirator

A new, in-mask sampling technique has been developed that enhances current quantitative respirator fit test methods. This new sampling technique eliminates the need for a permanently modified (probed) respirator for conducting fit tests. With this new technique, a sample was drawn from the breathing zone inside the respirator by means of a sampling adapter, which was temporarily attached between one of the air-purifying filters and the facepiece before a fit test was performed. To ensure that the performance of the respirator was not altered, the sampling adapter was designed so that all major functional aspects of the respirator were unchanged. This new sampling technique was evaluated on human test subjects by simultaneous sampling from a probed respirator by using two quantitative respirator fit test instruments. One instrument sampled through a conventional respirator probe; the other used the new method. Test results show that equivalent fit test data were obtained with both sampling techniques.

Endothelin induces vascular and mucosal lesions, enhances the injury by HCl/ethanol, and the antibody exerts gastroprotection

Vascular factors play an important role in the pathogenesis and prevention of acute gastric mucosal lesions. Endothelin-3 (ET-3), a potent vasoactive peptide, was infused intra-arterially to induce gastric microvascular and hemorrhagic mucosal lesions, and to enhance the damaging effects of dilute HCl and ethanol. ET-3 antibody was injected intravenously to decrease hemorrhagic mucosal lesions induced by ethanol. Locally infused ET (0.01, 0.1, and 1.0 nmol.100 g-1.min-1 for up to 15 min) was followed in some cases by intragastric dilute ethanol or HCl, which alone caused no or only mild vascular and mucosal lesions. Monastral blue was used to visualize and quantify vascular injury. ET-3 produced dose-dependent vascular lesions that affected the walls of mucosal capillaries and venules and induced mucosal congestion and focal endothelial labeling in vessels of the gastric muscular layers. The highest dose of ET induced hemorrhagic gastric mucosal lesions, mortality, and periods of hyper- and hypotension in the rat. Medium and low doses of ET-3 caused vascular injury, and dose-dependently potentiated the vascular and hemorrhagic mucosal lesions caused by dilute HCl and ethanol. Indomethacin slightly enhanced damage induced by ET and 50% ethanol, suggesting a limited mediatory role of prostaglandins in the ET-induced mucosal lesions. Anti-ET-3 serum dose-dependently decreased but did not abolish the hemorrhagic gastric mucosal lesions induced by 75% ethanol. Thus, ET-3 causes endothelial damage in capillaries and venules of rat stomach and predisposes to mucosal damage even after exposure to dilute ethanol or HCl. ET is more potent than leukotrienes and histamine and thus may play an important role in the mechanisms of acute gastric mucosal injury and protection where the vascular network appears to be a major target.

Elevated temperature alters the ionic dependence of amine-induced pacemaker activity in a conditional burster neuron

The anterior burster neuron of the lobster (Panulirus interruptus) stomatogastric ganglion is a conditional burster that functions as the primary pacemaker for the pyloric motor network. When modulatory inputs to this cell are blocked, it loses its bursting properties and becomes quiescent. Applications of the monoamines, dopamine, octopamine or serotonin restore rhythmic bursting in this cell (Flamm and Harris-Warrick 1986). At 15 degrees C, serotonin- and octopamine-induced oscillations depend critically upon sodium entry (blocked by low sodium saline or tetrodotoxin); dopamine-induced oscillations depend upon calcium entry (blocked by reduced extracellular calcium; Harris-Warrick and Flamm 1987). We show here that the ionic dependence of amine-induced oscillations in the anterior burster cell differs at 15 and 21 degrees C. At 21 degrees C, all amines have the potential to induce rhythmic oscillations in saline containing tetrodotoxin. At the elevated temperature and in tetrodotoxin, both calcium and sodium currents are essential for the maintenance of dopamine-induced oscillations; serotonin-induced oscillations do not depend upon either calcium or sodium alone; octopamine-induced oscillations do not depend upon calcium and show a variable dependence upon sodium. Thus, multiple ionic mechanisms, which vary with both the modulator and the ambient temperature, can be recruited to support rhythmic activity in a conditional burster neuron.

Paranoid and aggressive behavior in two obsessive-compulsive adolescents treated with clomipramine

Obsessive-compulsive disorder is increasingly recognized in patients of different age groups. Serotonergic agents, such as clomipramine, have been recently found to be useful in the management of this condition. However, unexpected side effects, such as dysphoria, aggressiveness, and paranoid ideation, may occur with therapeutic doses of this compound, as evidenced in the cases of two male adolescents presented here. Possible pathogenetic factors, involving serotonin and serotonin-receptor abnormalities are discussed. Management of these side effects is based on adequate dose reduction and monitorization.

Across-fiber patterns may contain a sensory code for stimulus intensity

Various models for sensory coding have used statistical approaches based on the assumption that the stimulus intensity parameter is represented in the afferent neurons as mean firing frequency. In this paper we question the assumption that this is the only code for intensity. We show that in lobster olfactory receptors narrowly tuned to hydroxyproline, an across-fiber pattern (AFP) code distinguished more concentration levels over a 5 log step range than a response magnitude code and, unlike the latter, was unaffected by response summation time. AFP discrimination of stimulus intensity appears to be based on high inter-cell response variability and low intra-cell response variability.

Temperature sensitivity of graded synaptic transmission in the lobster stomatogastric ganglion

We examined the temperature sensitivity of graded chemical synaptic strength within the pyloric circuit of the spiny lobster stomatogastric ganglion. Cooling from 20.4 degrees C to 11.3 degrees C reduced the graded synaptic potential (GSP) amplitude at all six pyloric synapses tested. Cooling appeared to reduce the slope of the linear part of the input-output curve at three of these synapses, and did not significantly alter the threshold for transmitter release at any synapses. Pairs of neurons with a presynaptic pyloric dilator (PD) cell showed reductions in graded synaptic strength at 16.5 degrees C but those with presynaptic lateral pyloric (LP) or ventral dilator (VD) cells did not. A generalized decrease in input resistance is not responsible for the reduced GSP amplitude upon cooling, as determined by input resistance, action potential amplitude and electrical coupling measurements. We conclude that cooling reduces graded chemical strength by a direct synaptic action. Since the PD and VD cells use the same transmitter and act on some of the same postsynaptic cells, their differential sensitivity to cooling further suggests a presynaptic site of action. The temperature range used in our experiments encompasses the range that the animal normally encounters in nature. Thus, the relative importance of graded synaptic interactions in generating the pyloric motor rhythm may vary with transient changes in temperature.

Aminergic modulation of graded synaptic transmission in the lobster stomatogastric ganglion

Graded chemical synaptic transmission is important for establishing the motor patterns produced by the pyloric central pattern generator (CPG) circuit of the lobster stomatogastric ganglion (Raper, 1979; Anderson and Barker, 1981; Graubard et al., 1983). We examined the modulatory effects of the amines dopamine (DA), serotonin (5-HT), and octopamine (Oct) on graded synaptic transmission at all the central chemical synapses made by the pyloric dilator (PD) neuron onto its follower cells, using synaptic input-output curves measured from cell somata. DA strongly reduced the graded synaptic strength at all the PD synapses. DA reduction of chemical synaptic strength from PD onto the inferior cardiac (IC) neuron could change the sign of synaptic interaction between these 2 cells from inhibitory to excitatory by uncovering a weak electrical connection. 5-HT had weaker and more variable effects, reducing graded synaptic strength from the PD onto the lateral pyloric and pyloric neurons and enhancing the weak synapse from the PD to the IC cell. Oct strongly enhanced the graded synaptic strength at all the PD central synapses. Oct enhancement of graded synaptic strength between the PD and IC cells could also change the sign of the interaction: weak, excitatory electrical coupling, which was sometimes dominant before Oct, was masked by the enhanced chemical inhibitory interaction during Oct application. Measurements of electrical coupling between 2 PD cells and between 2 postsynaptic cells suggest that Oct does not change the input resistance of these cells and may act directly at the PD synapses. The effects of DA and 5-HT are most easily explained by their general reductions in pre- and postsynaptic input resistance. DA, 5-HT, and Oct each produce a distinct pyloric motor pattern (Flamm and Harris-Warrick, 1986a). These amine-induced motor patterns may be explained by the unique actions of each amine on the intrinsic membrane properties of different pyloric CPG neurons (Flamm and Harris-Warrick, 1986b) and by modulation of graded synaptic transmission between the pyloric neurons.

Self-focused attention, gender, gender role, and vulnerability to negative affect

Research has independently shown that both gender and self-focused attention are linked to depression. In this article, we report a series of studies investigating the relation between these variables. Using a standard self-focusing manipulation, Study 1 suggested that women evidence a greater propensity to self-focus than men. We replicated these findings in Study 2. In Study 3, we conducted an experiment to determine if sex role in conjunction with experimentally increased self-focused attention would lead to more emotional distress after a negative event had occurred. Results suggested that feminine individuals who received a self-focusing manipulation responded with greater levels of self-focused attention and negative affect than did any other group. We interpreted findings in terms of a tendency to self-focus that might prime feminine people to experience depression, or alternately, as a lack of self-focusing that may insulate masculine individuals from the experience of depression.

Invariant imbedding T matrix approach to electromagnetic scattering

A new method for calculating electromagnetic scattering from an arbitrarily shaped, inhomogeneous, dielectric object is developed. The method is based on an invariant imbedding procedure for computing the T matrix that was originally developed to solve quantum mechanical scattering problems. The final outcome of this approach is a two-term recurrence relation which can be solved numerically for the T matrix. The limiting form of this recurrence relation is a first-order nonlinear differential equation that is identical in form to the quantum mechanical Calogero equation. The results of several test calculations are also presented.

Self-focused attention, gender, gender role, and vulnerability to negative affect

Research has independently shown that both gender and self-focused attention are linked to depression. In this article, we report a series of studies investigating the relation between these variables. Using a standard self-focusing manipulation, Study 1 suggested that women evidence a greater propensity to self-focus than men. We replicated these findings in Study 2. In Study 3, we conducted an experiment to determine if sex role in conjunction with experimentally increased self-focused attention would lead to more emotional distress after a negative event had occurred. Results suggested that feminine individuals who received a self-focusing manipulation responded with greater levels of self-focused attention and negative affect than did any other group. We interpreted findings in terms of a tendency to self-focus that might prime feminine people to experience depression, or alternately, as a lack of self-focusing that may insulate masculine individuals from the experience of depression.