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A halogen-bonded complex formed between methane and chlorine monofluoride has been isolated in the gas phase before the reaction between the components and has been characterised through its rotational spectrum, which is of the symmetric-top type but only exhibits K = 0 type transitions at the low effective temperature of the pulsed-jet experiment. Spectroscopic constants for two low-lying states that result from internal rotation of the CH4 subunit were detected for each of the two isotopic varieties H4C&middot, &middot, 35ClF and H4C&middot, 37ClF and were analysed to show that ClF lies on the symmetry axis with Cl located closer than F to the C atom, at the distance r0(C&middot, Cl) &cong, 3.28 &Aring, and with an intermolecular stretching force constant k&sigma, &cong, 4 N m&minus, 1. Ab initio calculations at the explicitly correlated level CCSD(T)(F12c)/cc-pVTZ-F12 show that in the equilibrium geometry, the ClF molecule lies along a C3 axis of CH4 and Cl is involved in a halogen bond. The Cl atom points at the nucleophilic region identified on the C3 axis, opposite the unique C&ndash, H bond and somewhere near the C atom and the tetrahedron face centre, with re(C&middot, Cl) = 3.191 &Aring, Atoms-in-molecules (AIM) theory shows a bond critical point between Cl and C, confirming the presence of a halogen bond. The energy that is required to dissociate the complex from the equilibrium conformation into its CH4 and ClF components is only De &cong, 5 kJ mol&minus, 1. A likely path for the internal rotation of the CH4 subunit is identified by calculations at the same level of theory, which also provide the variation of the energy of the system as a function of the motion along that path. The barrier to the motion along the path is only &cong, 20 cm&minus, 1.

Rats repeatedly exposed to the bar test following injections with a dopamine D2-like receptor antagonist such as haloperidol show increased descent latencies, suggesting that contextual stimuli may lose their ability to elicit approach and other responses. Here, we showed that rats took progressively longer to initiate descent from a horizontal bar across sessions following daily intraperitoneal treatment (paired group) with the D2-like receptor antagonist, spiroperidol (0.125 and 0.25 mg/kg), but not in the control group that received 0.25 mg/kg in their home cage and testing following saline. When both groups were tested following an injection of spiroperidol or following saline, a sensitized and a conditioned increase in descent latency, respectively, were observed in the paired but not in the unpaired group. No evidence of sensitization or conditioning was found with the substituted benzamide compound, eticlopride (0.15-0.5 mg/kg), or the D2-like receptor partial agonist, aripiprazole (0.25-0.5 mg/kg). The different effects of these agents on learning may be related to different region-specific affinities for dopamine receptors or differences in receptor dissociation profiles. We suggest that the behavioural changes observed in spiroperidol-treated rats may reflect inverse incentive learning.

Suggitt et al. reply to the concerns raised by Le Roux et al. on their original manuscript.

Human activity has sent many measures of biodiversity into long-term decline, and there are suggestions that the sheer scale of this impact is sufficient to consider the modern era as a geological epoch of its own, known as “The Anthropocene” [1]. However, recent meta-analyses show that local alpha diversity is often stable or slightly increasing [2, 3, 4]. Here, we show that the local alpha diversity (species richness) of plants found in quadrats and transects has increased the most in cooler regions of the world that have experienced the highest absolute changes (i.e., changes in either direction) in climate. The greatest statistical support is for the effects of precipitation change. On average, alpha diversity declined slightly (−4.2% per decade) in the third of sites that experienced the lowest precipitation change but increased (+10.8% per decade) in the third of sites with the highest precipitation change. These results suggest that the “perturbation” of local communities during climatic transitions increases the average number of species, at least temporarily, an effect likely to remain important as climate change continues.

Endoscopic fundoplication requires accurate evaluation of the gastroesophageal junction (GJ) to determine if hiatal hernia repair is necessary before fundoplication. We compared the endoscopic and laparoscopic evaluations of the GJ.A total of 53 patients with gastroesophageal reflux disease underwent a laparoscopic repair of a hiatal defect before endoscopic fundoplication. The video of the preoperative endoscopic evaluation was compared with the laparoscopic video (n = 44). Nine patients were excluded because both endoscopic and laparoscopic videos were not available. A 2-tailed paired t test was used to assess the difference between the 2 study groups.The greatest transverse dimension of the hiatus assessed endoscopically was 3.30 cm ± 1.00 vs 3.88 cm ± 1.03 assessed laparoscopically, P.001. In 22.8%, the average endoscopic Hill grade was lower than the estimated Hill grade when viewed laparoscopically. In 11.1% (range, 6% to 15%) of cases, the endoscopic view indicated a hiatal hernia repair was unnecessary when the matching laparoscopic view indicated hiatal repair would be needed.Endoscopic evaluation of the GJ may underestimate the radial size of the hiatal defect.

Ceramic metal halide lamps with rated powers of 70 W and 150 W are dimmed by reducing their operating power. Under dimmed conditions, photometric, colorimetric and electric parameters, as well as the temperature distribution of the outer wall of the arc tube have been measured. As the lamp power is reduced, luminous efficacy and colour rendering index decrease while correlated colour temperature rises. For each lamp, at 70% of its rated power, the luminous efficacy is greater than 80 lm/W, colour rendering index is above 74 and correlated colour temperature increases by less than 800 K. Dimming applications of these lamps are validated by these parameters. Furthermore, the complicated variation of lamp parameters as a function of operating power is explained by the variation of metal halide vapour pressure with wall temperature.

The phenomenon of volcanic fallout ash from Mt. Etna in Sicily (Italy) is well known and frequent in recent years, as in the period 2001-2004. As a consequence, significant problems for the population, road, rail and air traffic and production activities have occurred. The industrial areas of Catania and Augusta-Priolo, located in south eastern Sicily, might be involved during particular weather conditions. This paper aims at determining the potential scenarios of damage to industrial facilities caused by volcanic ash fallout. The work has been focused on the study of both fixed and floating roof storage tanks, containing flammable liquids, and examines extreme failures damage causing the greatest loss of containment for these facilities. To include scenarios arising from natural phenomena (Na-Tech events) in the standard risk assessment procedure, the estimation of the vulnerability of these facilities is necessary. The study has been applied to the area surrounding Mt. Etna, and the procedure can also be extended to other case studies. © 2012 Springer Science+Business Media Dordrecht.

The physics of gas discharge lamps is reviewed, with particular emphasis on new developments in the field. In addition to the most important light sources (fluorescent and high-pressure discharge lamps), a number of less common sources are also discussed. The review covers not only the physics of the discharges themselves, but also their interactions with lamp materials and external driving circuits. Important historical steps in lamp product development are described and special sections are devoted to the properties of light, diagnostics, and modeling of the discharges. A detailed, but not exhaustive, review of the published literature is provided and some possible future directions for research in the subject are discussed.

Since electrode life is the major limiting factor in operating fluorescent lamps, many lighting companies have introduced “electrodeless” fluorescent lamps, using inductively coupled discharges. These lamps often operate at much higher power loadings than standard lamps and numerical models have not been successful in reproducing experimental measurements in the parameter ranges of interest. A comprehensive research program was undertaken to study the fundamental physical processes of these discharges, co-funded by the Electric Power Research Institute (EPRI) and OSRAM SYLVANIA under the name of ALITE. The program included experiments and modeling of radiation transport, computations of electron–atom and atom–atom cross sections and the first comprehensive power balance studies of a highly loaded fluorescent lamp. Results from the program and their importance to the understanding of the physics of fluorescent lamps are discussed, with particular emphasis on the important collisional and radiative processes. Comparisons between results of experimental measurements and numerical models are presented.

A small ultraviolet-visible absorption spectrometer which uses fibre optic coupled immersion probes has been incorporated into a laboratory scale reaction calorimeter. The combined instrument has been tried out using the hydrolysis of acetic anhydride as a test reaction. With the calorimeter operating in the isoperibolic mode good agreement is found for the pseudo-first order reaction rate constant as determined from spectroscopic and calorimetric measurements. Experiments have been made in order to follow the reaction indirectly using optical pH measurements with acid-base indicators. The possibility of determining the temperature dependence of the rate constant in a single experiment has also been investigated.

We have studied, both experimentally and numerically, the radiometric efficiency of low-pressure barium–argon positive column discharges. Using a 14 mm inner diameter alumina discharge tube to reduce chemical reactivity, we have operated discharges with Ba vapor pressures corresponding to a range of oven temperatures from 600 to 800 °C, Ar buffer gas pressures of 0.5 and 5 Torr, and currents of 100–800 mA. The spectral power distribution has been determined by examining the visible radiation emitted perpendicular to the discharge axis from a small aperture in the side of the alumina discharge tube. Absolute emitted powers were determined by comparison to a calibrated tungsten–quartz–halogen lamp. The measured efficiencies for production of visible radiation from the positive column ranged from 2.5% to 52%. These efficiencies correspond to luminous efficacies ranging from 6 to 97 lm/W. Strong emission on Ba ion lines at 455.4, 493.4, 614.2, and 649.7 nm contributed significantly to the best efficiency, 52%, and yielded a white light. A numerical model, incorporating a substantial number of excited levels and atomic processes, has been used to examine the same conditions. The model reproduces most of the major experimental trends.

We report the results of an experimental and theoretical study on the feasibility of a barium low pressure discharge as a potential new light source. Barium has a strong neutral resonance line at 553.5 nm, near the center of the eye’s response curve, as well as several red and blue lines from barium ions. Due to the strong reactivity of barium with a wide variety of standard lamp materials, experiments were performed in arc tubes lined with yttria (Y2O3). A wide range of parameter space was explored in buffer gas pressure (1–30 Torr), gas type (argon, neon, and krypton), barium temperature (400–760 °C), and arc current (0.05–1.0 A). The numerical model qualitatively predicted the influence of these parameters on light output. However, the predicted efficacies of up to 100 lm/W were considerably higher than the measured values. The best positive column efficacy achieved was 50 lm/W in a sealed yttria lined quartz tube with 5 Torr argon operating at 400 mA at 760 °C. Possible reasons for this discrepancy ar...

OBJECTIVE To estimate the rate of combination antiretroviral treatment change and factors associated with combination antiretroviral treatment change among patients recruited in the Australian HIV Observational Database (AHOD). METHODS Analyses were based on patients in the AHOD who had commenced combination antiretroviral treatment after 1 January 1997. Combination antiretroviral treatment change was defined as the addition or change of at least one antiretroviral drug. A random-effect Poisson regression model was used to assess factors associated with increased rates of combination antiretroviral treatment change. RESULTS A total of 596 patients in the AHOD were included in the analysis, with a median follow-up of 2.3 years. The overall rate of antiretroviral treatment change in this group was 0.45 combinations per year. In a multivariate analysis, a low CD4 count (< 200 cells/microL) at baseline was associated with an increased rate of treatment change [rate ratio (RR)=1.43; 95% confidence interval (CI), 1.13, 1.80; P=0.003)]. Combinations including a nonnucleoside reverse transcriptase inhibitor were also associated with slower rates of change than treatment combinations including a protease inhibitor (RR=0.64, 95% CI, 0.51, 0.80, P < 0.001). CONCLUSION Initiating combination antiretroviral at a CD4 cell count < 200 cells/microL may be associated with poorer patient outcomes. However, the possibility that clinician or patient concerns about low immunological status led to faster rates of treatment change in this group cannot be discounted.

The [1.1.1]cryptand is a proton sponge able to change slowly and almost linearly the pH of a solution (range 4–10) in such a way that it can be used as a chemical device in the automatic control of a variety of pH-sensitive processes under variable-pH conditions. A simple mathematical model describing its behaviour, based on the fundamental work by Lehn's group, and computer simulation carried out for different values of concentration and starting pH (in agreement with produced experimental data) enable the visualization of the pH-time profiles for any possible experimental conditions and provide directions for its use as a molecular burette. The interference with species present in the reaction vessel and acting as buffers is also discussed and measures are suggested for avoiding problems.

Limitations in home monitoring technology have precluded longitudinal studies of hemoglobin oxygen saturation during unperturbed sleep. The memory monitor used in the Collaborative Home Infant Monitoring Evaluation addresses these limitations. We studied 64 healthy term infants at 2 to 25 weeks of age. We analyzed hemoglobin oxygen saturation by pulse oximetry (SpO(2)), respiratory inductance plethysmography, heart rate, and sleep position during 35, 127 epochs automatically recorded during the first 3 minutes of each hour. For each epoch baseline SpO(2) was determined during >/=10 s of quiet breathing. Acute decreases of at least 10 saturation points and /=5 s were identified, and the lowest SpO(2) was noted. The median baseline SpO(2) was 97.9% and did not change with age or sleep position. The baseline SpO(2) was /=16% were associated with isolated apnea. With the use of multivariate analyses, the odds of having an acute decrease increased as the number of epochs with periodic breathing increased, and they lessened significantly with age. We conclude that healthy infants generally have baseline SpO(2) levels >95%. The transient acute decreases are correlated with younger age, periodic breathing, and apnea and appear to be part of normal breathing and oxygenation behavior.

The ground-state rotational spectra of the six isotopomers 16O12C ··· 79Br79Br, 16O12C ··· 81Br79Br, 16O12C ··· 81Br81Br, 16O12C ··· 79Br81Br, 16O13C ··· 79Br79Br, 16O13C ··· 81Br79Br, were observed by pulsed-nozzle, Fourier-transform microwave spectroscopy. The spectroscopic constants B O, D J, χ aa (Bri), χ aa (Bro), Mbb (Bri) and M bb (Bro), where i = inner and o = outer, were determined for each isotopomer. The complex is linear, with the weak bond between the C atom of CO and Bri. The rotational constants were used to determine the distance r(C ··· Bri) = 3.1058A and to show that the Br—Br bond lengthens by ∼0.005–0.01A on complex formation. The intermolecular stretching force constant kσ = 5.0 Nm−1 was obtained from DJ and the Br nuclear quadrupole coupling constants were interpreted to reveal that a fraction δ = 0.02 of an electronic charge is transferred from Bri to Bro when Br2 is subsumed into the complex. Properties of the two series OC ··· XY and H3N ··· XY, where XY = C12, Br2 and BrC1, are c...

Numerical simulations of radiation transport in cylindrical geometry are used to determine the effect of radially symmetric inhomogeneities. The focus of this study are inhomogeneities such as may be produced by radial cataphoresis or temperature gradients in cylindrical glow discharges, i.e., a quadratic profile of absorbing atoms which has a minimum on the axis of the cylinder. A propogator function analysis of the Holstein–Biberman equation and a Monte Carlo simulation of resonance photon scattering are simultaneously used to examine three limiting cases of interest: (i) a pure Doppler broadened atomic lineshape, (ii) a pure Lorentz atomic lineshape produced by foreign gas broadening, and (iii) a pure Lorentz atomic lineshape produced by resonance collision broadening. The fundamental mode distribution of excited atoms, the fundamental mode trapped decay rate, and the volume-averaged escape rate for a homogeneous production rate per unit volume are calculated for each of these cases. The trapped decay rates are found to change modestly (depending upon lineshape) as the degree of inhomogeneity is increased, if the volume integral of the absorbing atom density remains fixed. Correction factors for the fundamental mode trapped decay rate are reported.

The rotational spectra of the isotopomers mecp···H79Br, mecp···H81Br and mecp···D79Br (mecp=methylenecyclopropane) of a complex formed between mecp and hydrogen bromide were observed by using a pulsed-nozzle, Fourier-transform microwave spectrometer. Accurate values of the rotational constants A0, B0 and C0, the centrifugal distortion constants ΔJ, ΔJK and δJ, and the components χaa, (χbb-χcc) and χab of the Br nuclear quadrupole coupling tensor were determined in each case. These spectroscopic constants were interpreted to show that mecp···HBr has Cs symmetry, with the HBr subunit lying in the principal inertial plane ab, which coincides with the molecular symmetry plane. The H atom of HBr forms a hydrogen bond to the centre (*) of the mecp π bond. The angle φ included by the unique C atom of the cyclopropyl ring, the centre of the π bond and the H atom of HBr is 88.8(10)° and the distance r(*···H)=2.353(18) A. The hydrogen bond *···H–Br deviates from linearity by ϑ=18.03(23)° in a direction that suggests a secondary interaction of δ-Br with two of the protons of the cyclopropyl ring. The properties φ, ϑ, r(Z···X) and r(Hring···Y) of the complexes (CH2)2Z···XY, where Z=O, S or C2CH2 and XY=HCl, HBr or ClF are compared and the reason why the hydrogen bonds Z···H–Y are significantly nonlinear, while the ‘chlorine’ bonds Z···Cl–F remain close to linearity, is considered.

The ground-state rotational spectra of the three isotopomers C5H514N···H35Cl, C5H514N···H37Cl and C5H514N···D35Cl of a complex formed by pyridine with hydrogen chloride have been observed by using a fast-mixing nozzle in combination with a pulsed-nozzle, FT microwave spectrometer. Rotational constants A0, B0, C0, centrifugal distortion constants, ΔJ, ΔJK, δJ, δK and nuclear quadrupole coupling constants χaa(A) and χbb(A) − χcc(A) (where A = 14N or Cl) were determined in each case. A detailed interpretation of the spectroscopic constants led to the conclusion that the observed complex has a planar, C2v geometry, with the HCl subunit forming a hydrogen bond to N and lying along the C2 axis of pyridine. The nitrogen to chlorine distance was determined to be 2.999(2) A. The magnitudes of the nuclear quadrupole coupling constants χaa(A) and the intermolecular stretching force constants kσ in comparison with those expected in the hydrogen-bond C5H5N···HCl and ion-pair C5H5NH+···Cl− limits show that the extent of proton transfer from HCl to pyridine is small.

Despite potential benefits, human milk may fail to meet preterm infants' nutrient requirements. We tested the hypothesis that fortified breast milk, fed alone or with preterm formula, would improve neurodevelopment and growth at 18-mo follow-up without adverse short-term clinical or biochemical consequences. Two hundred seventy-five preterm infants from two medical centers (birth weight < 1850 g; mean gestation 29.8 +/- 2.7 wk) whose mothers chose to provide breast milk were randomly assigned to receive for a mean of 39 d a multinutrient fortifier or control supplement containing phosphate and vitamins. Breast milk comprised 47.6% and 46.4% of enteral intake in fortified and control groups, respectively; preterm formula supplements were used when insufficient breast milk was available. Overall, there were no significant growth advantages with fortification; although, when breast milk exceeded 50% of intake, fortification promoted faster weight gain (an advantage of 1.6 g.kg-1.d-1; 95% CI: 0.1, 3.1; P < 0.05). Compared with control infants, the fortified group showed 1) higher plasma urea from week 2 (P = 0.04), 2) higher plasma calcium (mean 2.34 +/- 0.01 compared with 2.27 +/- 0.02 mmol/L; P = 0.003), 3) a greater rise in alkaline phosphatase by week 6 (P = 0.04), 4) more clinical infections (suspected plus proven; 43% compared with 31%, P = 0.04), 5) a nonsignificantly increased incidence of necrotizing enterocolitis (5.8% compared with 2.2%, P = 0.12), and 6) higher white cell and platelet counts. Developmental scores at 18 mo were slightly but not significantly higher in the fortified group. This study confirmed that breast milk fortifiers can improve short-term growth (when breast milk intakes are high); but beneficial effects on long-term development remained unproven. Future research is required to evaluate potential adverse consequences and explore more optimal fortification strategies.

The electrical conductivity is an important parameter in understanding the mechanism by which power is coupled to a radio‐frequency (rf) discharge plasma, as well as in determining the external electrical characteristics of the discharge. We present the results of computations of the resistive and reactive components of the collisional impedance of an argon plasma at 13.56 MHz. The plasma conductivity is computed from the two‐term solution to the Boltzmann equation, and includes the velocity dependence of the electron collision frequency, as well as non‐Maxwellian electron energy distribution functions. We compare these results with those obtained from the widely used classical expression for plasma impedance, in which the electron collision frequency is computed either in the dc or high frequency limit. Our results show that neither of the classical limiting expressions are adequate for discharge pressures in the range of few mTorr to a few Torr, which includes the region of operation for many rf discharges used in many applications of plasma technology. Further, the classical formula assumes that in the high‐frequency limit the plasma reactance is due entirely to electron inertia. We demonstrate that the plasma reactance may be strongly influenced, and in some cases dominated, by electron collisions. Results are presented in graphical form, which are useful in evaluating the importance of these effects on the interpretation of experimental results and the modeling of rf discharges.

The ground-state rotational spectra of the three isotopomers 14N2⋯35ClF, 15N2⋯35ClF and 15N2⋯37ClF of a complex formed by dinitrogen and chlorine monofluoride have been observed with a pulsed-nozzle, Fourier-transform microwave spectrometer. The spectroscopic constants B0, DJ, χaa(A)(A =14Ni, 14No or Cl) and Mbb(Cl) are reported. The complex is shown to have a linear (or nearly linear) arrangement NoNi⋯ClF of the nuclei in the equilibrium conformation with r(Ni⋯Cl)= 2.920(2)A. The intermolecular stretching force constant, kσ= 5.00(5) N m–1, is implied by the centrifugal distortion constant DJ. Interpretation of the nuclear quadrupole coupling constants χaa(A) leads to the oscillation angles θav= cos–1〈cos2θ〉1/2= 17.8(5)° and ϕav= cos–1〈cos2θ〉1/2= 10(3)° for the N2 and ClF subunits, respectively. Additionally, the diffence χaa(Ni)–χaa(No) leads, on the basis of a simple model, to the conclusion that the polarisation of N2 attending complex formation is equivalent to the transfer of a fraction δ≈ 0.02 of an electronic charge from No to Ni. A comparison of the properties of four related complexes N2⋯YF and OC⋯YF, where Y = Cl or H, is presented.

Fifteen normal volunteers were administered placebo, 0.250, 0.375 and 0.500 mg of triazolam in a double- blind cross-over design. Triazolam induced robust dose-dependent impairments in explicit memory of information presented after drug administration. Subjects were unaware of their memory deficit (an impairment in meta-cognition). In contrast, memory for information presented prior to the administration of triazolam was facilitated following the administration of low doses of triazolam. Implicit memory and access to knowledge memory was unaltered by this benzodiazepine. An analysis of these results controlling for concurrent sedation as measured subjectively, through the use of self rating scales and objectively, based upon psychomotor performance, demonstrated that the amnestic effects of triazolam are largely independent of sedative effects. The pattern of memory changes induced by benzodiazepines, such as triazolam, is similar to the memory inpairment expressed in amnestic patients but unlike the pattern of impaired memory evident in dementia such as Alzheimer's disease.

Loss of temperature control is one of the major reasons that can lead to runaway reaction. This occurrence is commonly named thermal runway. The aim of this paper is the application of thermal runaway criteria in order to predict the onset of runaway phenomena and define the range of stability related to operating conditions in the reactor, with specific reference to the esterification of acetic anhydride and methanol catalysed by sulphuric acid tested in isoperibolic conditions. The isoperibolic calorimeter has also been used to obtain thermodynamic, kinetic and physical chemistry data necessary to develop a model for the reaction. Some runaway criteria applied in this work require a model for the process, so a model for the analyzed system been developed. Because of the modest reaction enthalpy and low activation energy this reacting system provide a severe test to the runaway criteria. In this work, various runaway criteria have been applied to the experimental and simulated data and the results obtained have been compared.

The ground-state rotational spectra of two isotopomers, (CH 2 ) 2 32 S·HC 14 N and (CH 2 ) 2 32 S·HC 15 N, of a complex formed by thiirane with hydrogen cyanide were analysed to give rotational constants, centrifugal distortion constants and 14 N-nuclear quadrupole coupling constants. The spectroscopic constants were interpreted in terms of a geometry of the complex characterised by the angle φ = 89.2(9)° made by the S·H internuclear axis with the thiirane heavy atom plane at S and a nonlinearity θ≈43° of the S·H-C hydrogen bond. This large nonlinearity is contrasted with that in (CH 2 ) 2 O·HCN and the difference discussed in terms of a simple model of the hydrogen bond.

A synthesis is provided of Late-glacial (14-9 ka BP) environmental changes in lowland Switzerland (the `Swiss Plateau'). The chronology of deglaciation and subsequent developments in vegetation cover in the area are summarised. The sequence of climatic variations experienced in the region during the Late-glacial is then described and a curve representing the main palaeotemperature variations is presented.

The microwave spectrum of phthalan has been observed in the frequency range of 18–70 GHz. The spectra of the ground and ten excited vibrational states have been assigned and rotational and quartic centrifugal distortion constants have been obtained from semirigid rotor fits to the observed line frequencies. The microwave spectrum is not consistent with either the C2v equilibrium conformation deduced from the far infrared spectrum or the C2 equilibrium conformation obtained from the single vibronic level fluorescence spectra. The microwave data indicates that the bending of the five membered ring is a very anharmonic vibration with a double minimum potential function with a low barrier and that phthalan therefore has a Cs equilibrium conformation. The previous spectroscopic data can be reinterpreted in a manner consistent with this and gives a barrier height of 38 cm-1. The twisting of the five membered ring is a reasonably harmonic vibration and its fundamental wave-number is ∼ 180 cm-1. The microwave dat...

The ground-state rotational spectra of five isotopomers of the ‘charge-transfer’ complex H3N⋯Cl2 have been observed by pulsed-nozzle, Fourier-transform microwave spectroscopy. The complex has C3v symmetry with the nuclei in the order H3N⋯Cl—Cl. A detailed analysis of the Cl nuclear quadrupole hyperfine structure in transitions of H315N⋯35Cl2, H315N⋯35Cl37Cl, and H315N⋯37Cl35Cl gave the rotational constant, Bo, the centrifugal distortion constants Dj and Djk, and the nuclear quadrupole coupling constants χ(Cli) and χ(Clo)(i = inner, o = outer) in each case. The distance r(N⋯Cli) was obtained by an rs-type method and an ro-type method and lies in the range 2.73 ± 0.03 A. A detailed analysis that allowed for bond shrinkage on isotopic substitution in the 35Cl2 subunit of H315N⋯35Cl2 gave the rs-type coordinates of Cli and Clo and hence the distance rs(Cl—Cl)= 2.00 A. This value is very close to that in free Cl2 and indicates only a slight perturbation of this subunit when the complex is formed. The relatively small intermolecular stretching force constant, kσ= 12.71(3) N m–1 determined from DJ and the weak perturbation of χ(Cli) and χ(Clo) from the value in free Cl2, reinforce this conclusion. The observed difference χ(35Clo)–χ(35Cli)= 13.99 MHz can be interpreted in terms of a transfer of 0.064e from Cli to Clo on formation of H315N⋯35Cl2. It seems likely that the molecular interaction is mainly electrostatic in origin and charge-transfer effects are small.

It can be extremely difficult to interpret the results of experiments in which a treatment is found to antagonize the behavioural effects of a drug. This article discusses strategies that can be used to help identify the nature of the antagonism and examines what such experiments tell us about the mechanisms underlying the drug's behavioural effects. Examples are taken from research with both benzodiazepines and ethanol. It is suggested that behavioural studies using different strategies to reduce the effects of a drug will further enhance our understanding of the mechanisms mediating the drug's effects. Such studies will include comparisons between the effects of chronic drug exposure (tolerance studies), genetic manipulations, and pharmacological treatments.

The conformation and ring-puckering vibration of 2-methoxyloxetane have been studied using microwave spectroscopy and ab initio computations. The microwave spectra of the ground and first four excited states of the ring-puckering vibration have been observed in the frequency range 8–40 GHz and the rotational and quadratic centrifugal distortion constants have been determined. Vibrational energy separations have been obtained from relative intensity measurements. The electric dipole moment (in D) of the ground vibrational state has been determined from Stark effect measurements as μ a = 0.0187 (5), μ b = 1.852 (2), μ c = 0.08 (3), and μ t = 1.854 (3). The vibrational energy separations and the vibrational dependence of the rotational constants suggest that the ring-puckering vibrational has an asymmetric single minimum potential function and also gave a revised assignment of the far infrared spectrum (J. Mol. Struct. 56 (1979) 157). A combined fit to the rotational constants, vibrational energy separations and far infrared vibrational frequencies has been used to determine a reduced potential for the ring puckering vibration. The partial derivatives of the rotational constants with respect to the reduced ring-puckering coordinate show that the equilibrium conformation has the methyl group in the equatorial position. Ab initio computations of the ring-puckering potential function have been made using 6-31G * orbitals and full geometry optimization. These computations also show the molecule to have an asymmetric single minimum potential function with an equatorial equilibrium conformation.

In the 60 years since the Universal Declaration of Human Rights was promulgated, the promise of achieving respect for the human rights, health and well being of all is becoming an ever more distant prospect. We have not even remotely met the challenge of improving health for a large proportion of the world's population, and the prospects for improving global health seem to be receding in the current deteriorating economic and political climate. As global health remains one of the most pressing problems of our time, we must question the values that direct our actions and current approaches, which proclaim 'human rights to health' but which subsume these rights to a broader paradigm of unregulated global market economics and national politics, rather than working to make these oft-contradictory goals mutually compatible through justifiable and accountable global governance processes. We suggest that a new balance of values and new ways of thinking and acting are needed. These must transcend national and institutional boundaries and recognise that health in the most privileged nations is closely linked to health and disease in impoverished countries. Sustainable development of health and well-being is a necessity for all, and values for health should permeate every area of social and economic activity.

Low-pressure gas discharge modeling is reviewed, both from a historical perspective and for current industrial applications. An overview of the basic mathematical and physical models used to describe low-pressure discharges is given, together with a summary of the most common numerical techniques which have been adopted. Modelling of the DC glow discharge and discharges maintained by high-frequency (RF and microwave) electromagnetic fields is reviewed with illustrations of the validity of these models in predicting discharge properties and explaining and interpreting experimental results.

The hydrogen-bonded dimer CH 3 NC...HCl has been isolated in a pulsed jet by keeping the reactive components CH 3 NC and HCl separate until the point at which they expand into the evacuated Fabry-Perot cavity of a pulsed nozzle Fourier-transform microwave spectrometer. The rotational spectra of the three symmetric-top isotopomers CH 3 NC...H 35 Cl, CH 3 NC...H 37 Cl, and CH 3 NC...D 35 Cl detected in this way have been analyzed to give the ground-state spectroscopic constants B 0 , D J , D JK , and χ (Cl)

A model of the negative glow of a low‐pressure Hg‐Ar discharge is described. The model contains a number of important physical processes (in particular noble‐gas excitation and multiple‐step ionization) that have not been included in earlier models. The model has also been coupled to a simple description of the Faraday dark space to enable predictions to be made of the axial density and potential profiles across the whole negative‐glow Faraday dark‐space positive‐column region. Results of a number of numerical computations are presented and in general these have been found to be in agreement with experimental observations. The effect of varying the various input parameters to the model on its predictions has also been studied and the results of this will also be presented.

The effects of a benzodiazepine (triazolam 0.25 and 0.50 mg) on different aspects of cognitive function were assessed. Triazolam impaired free recall and recognition of information presented after drug administration. In contrast to these impairments in explicit memory, a memory function that did not require conscious awareness was not altered by triazolam. Similarly, triazolam did not affect subjects' abilities to access semantic memory.