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On the basis of the thought that the minimum system realization plays the role as a coagulator of structural information and contains abundant information on the structure, this paper proposes a new method, which combines minimum system realization and sensitivity analysis, for structural damage detection. The structural damage detection procedure consists of three steps: (1) identifying the minimum system realization matrixes A, B, and R using the structural response data; (2) defining the mode vector, which is based on minimum system realization matrix, by introducing the concept of the measurement; (3) identifying the location and severity of the damage step by step by continuously rotating the mode vector. The proposed method was verified through a five-floor frame model. As demonstrated by numerical simulation, the proposed method based on the combination of the minimum realization system and sensitivity analysis is effective for the damage detection of frame structure. This method not only can detect the damage and quantify the damage severity, but also is not sensitive to the noise.

Facial recognition is a complex skill necessary for successful human interpersonal and social interactions. Given that the most prevalent disorder of social interaction is autism spectrum disorder (ASD), a number of studies have investigated and found impaired facial recognition abilities in people with ASD. Further, this impairment may be critically involved in mediating the deficits in interpersonal and social interactions in people with ASD. We sought to address the question of whether face processing is impaired in children with ASD in the current study. While there were a number of differences in visual search behaviours between the 19 children with ASD and the 15 controls, this did not manifest in deficits in facial recognition accuracy. In addition, there were notable differences with respect to eye fixation behaviours and recognition accuracy in this study compared to the findings in a previous similar study conducted in adults with ASD. These differences suggest a performance enhancing developmental trajectory in facial processing in controls that may not be present in individuals with ASD.

The authors reviewed the clinical and electrophysiological features in 20 consecutive adult patients with Guillain-Barre Syndrome (GBS) admitted to a regional hospital in Hong Kong from 1993 to 1998. The majority of cases in this locality consists of the demyelinating form of GBS; epidemic, acute motor axonal neuropathy is not the predominant form. The incidence of GBS in this region of China was 0.44 per 100,000.

The two‐beam photoacoustic phase measurement was applied to measure quantitatively the thermal diffusivity (αs) of a ceramic bulk high‐Tc superconductor. Neglecting the effects of thermal dilation, and thermoelastic bending was proved valid in accordance with our composite piston model for the chosen experimental conditions. It was found that αs shows different features at the onset and offset temperatures corresponding to the normal–superconducting (NS) transition. A dip was seen at the resistivity transition onset temperature and a cusp at the offset temperature where the electrical resistance disappears. The presence of the cusp at the offset temperature is proposed to be related to weak coupling between superconducting grains. Our studies indicate that the two‐beam phase measurement is a very sensitive method for superconductor characterization and NS transition detection. The experimental results also confirm the presence of a large energy gap and strong electron–phonon coupling mechanism in the YBCO...

To account for low field microwave absorption in high-T c superconducting cuprates situated in the electron spin resonance configuration, an elegant model based on viscous fluxon motion has been proposed by Portiset al. [11–13]. In view of this model, however, derivations of neither the explicit expression of the power absorption nor the signal had been addressed. In this publication, the stated expressions are derived by fusing the idea of Portiset al. [11–13] and that of Kessleret al. and Dulcicet al. [20,21].

Sensory evaluation plays an important role in the quality control of food productions. Sensory data obtained through sensory evaluation are generally subjective, vague and uncertain. Classically, factorial multivariate methods such as Principle Component Analysis (PCA), Partial Least Square (PLS) method, Multiple Regression (MLR) method and Response Surface Method (RSM) are the common tools used to analyse sensory data. These methods can model some of the sensory data but may not be robust enough to analyse nonlinear data. In these situations, intelligent modelling techniques such as Fuzzy Logic and Artificial neural network (ANNs) emerged to solve the vagueness and uncertainty of sensory data. This paper outlines literature of intelligent sensory modelling on sensory data analysis.

This quasi-experimental study was carried out to evaluate the effectiveness of an eight-week multi-disciplinary pulmonary rehabilitation programme in improving nutritional and functional status and quality of life of COPD out patients at Hospital Universiti Kebangsaan Malaysia. A total of 9 COPD outpatients aged 40 years and above (6 men and 3 women) completed at least 50% of 16 sessions of an eight-week pulmonary rehabilitation programme. Their nutritional and functional status and rating of quality of life were measured at baseline (0 day) and after 8 weeks and these were compared to those of the control group matched for age, comprising 13 subjects (11 men and 2 women). Nutritional status was determined using anthropometry, body composition (Bioelectrical Impedance Analysis) and three-day food record. Assessment of appetite for food was also carried out using the Simplified Nutritional Assessment Questionnaire (SNAQ). Functional status was assessed using the Pulmonary Functional Status and Dyspnea Questionnaire-modified version(PFSDQ-M). The handgrip strength was also measured using handgrip dynamometer. The SF36 questionnaire was used to measure the quality of life of the subjects. There was a reduction in dyspnea (-49.0%, p0.05) and fatigue (-47.8%, p0.05) in men after the intervention programme, as compared to their controls (dyspnea -2.9% and fatigue 8.9%). Quality of life in this group was also significantly improved by 31.8% (p0.05) as compared to their controls (-3.0%,p0.05). Similar trends were noted for the women, although the difference was not significant. No significant changes were seen in nutritional status assessed by anthropometry, dietary intake and appetite. However, there was a trend of increased nutrient intake and SNAQ score in the intervention group as compared to control. An eight-week pulmonary rehabilitation programme was effective in improving the functional status particularly in men, by reducing dyspnea and fatigue; and also improving their quality of life, but was not effective in changing the nutritional status.

We investigated the age-related bone mineral content (BMC), bone mineral density (BMD) and the tempo of growth in BMC and BMD at lumbar spine and forearm in 455 Chinese girls aged 6-18 yr. BMC and BMD at the anteroposterior lumbar spine (LS), the left forearm (radius+ulna ultradistal, R+UUD) and one-third region (R+U1/3) were measured using a dual-energy X-ray bone densitometer (DXA). BMC and BMD exhibited different change patterns with the age changes. There were significant correlations between age, height, weight and BMC and BMD at LS, R+UUD and R+U1/3 sites. BMC and BMD increased significantly with increments in pubertal stages at LS, R+UUD and R+U1/3 sites. In conclusion, our study showed that Tanner stage had a significant positive association with BMC and BMD of the lumbar spine and forearm. The differences were found in the growth tempo of BMC and BMD within a region and between the spine and forearm. Both BMD and BMC were recommended to evaluate the bone health in children and adolescents.

The purpose of this review was to build upon a recent review by Weigelt et al. which examined visual search strategies and face identification between individuals with autism spectrum disorders (ASD) and typically developing peers. Seven databases, CINAHL Plus, EMBASE, ERIC, Medline, Proquest, PsychInfo and PubMed were used to locate published scientific studies matching our inclusion criteria. A total of 28 articles not included in Weigelt et al. met criteria for inclusion into this systematic review. Of these 28 studies, 16 were available and met criteria at the time of the previous review, but were mistakenly excluded; and twelve were recently published. Weigelt et al. found quantitative, but not qualitative, differences in face identification in individuals with ASD. In contrast, the current systematic review found both qualitative and quantitative differences in face identification between individuals with and without ASD. There is a large inconsistency in findings across the eye tracking and neurobiological studies reviewed. Recommendations for future research in face recognition in ASD were discussed. Funding Agencies|Cooperative Research Centre for Living with Autism Spectrum Disorders (Autism CRC) under the Australian Governments Cooperative Research Centres Program

Statistical atlases built by point distribution models (PDMs) using a novel hybrid 3D shape model were used for surface reconstruction. The hybrid shape model removes the need for global scaling in aligning training examples and instance generation, thereby allowing the PDM to capture a wider range of variations. The atlases can be used to reconstruct, or deformably register, the surface model of an object from just two to four 2D x-ray projections of the object. The methods was tested using proximal and distal femurs. Results of simulated projections and fluoroscopic images of cadaver knees show that the new instances can be registered with an accuracy of about 2 mm.

Accuracies of a point-based and an intensity-based fluoroscopic methods of assessing patella tracking were determined by comparing the pattern of patellar motion with respect to orientation (flexion, internal rotation, and lateral tilt) and translation (lateral, proximal, and anterior) with the pattern of patellar motion measured using Roentgen stereophotogrammetric analysis in three cadaver knee specimens. Each pose in the patellar motion could be obtained from single as well as multiple calibrated fluoroscopic images. The errors using the intensity-based method were slightly higher than those of the point-based method, but they appear to be sufficiently low to detect clinically significant differences in patellar kinematics.

Study the occlusal force of wedge shaped teeth defect and its relation with the clinical condition.Use the method of clinical examination and plaster model measurement to decide the parameters of axial gradient degree of the teeth, abrasion index, missing teeth number and so on; Adopt the computer image processing technology and program to analyse the photocclusion sheet, take the date and image information of occlusion force, areas, and occlusal stress of wedge shaped teeth defect.The occlusion contact data and graph of wedge-shaped teeth defect had the features of trauma occlusion. 42.97% of them has the larger axial gradient degree, 96.09% of them has abration in different classes, 46.29% missing the front teeth and 57.03% missing the buccal teeth. Occlusal contact force increase took up 78.91% in the wedge shaped teeth defect.It can be concluded that the not uniformly distributed occlusal force produced from the larger axial gradient degree, the defect of dentition, and the abrasion of teeth, may be the important factors which cause wedge shaped teeth defect.

Objective: This study investigated the consistency of condom use and the prevalence of self-reported sexually transmitted diseases (STD) among male Hong Kong commercial sex clients with respect to the geographical location of these transactions. Design and methods: Male clients were identified via three independent population based surveys conducted in 1998 1999 and 2001. A unique confidential telephone system was used to collect sensitive information. Results: Respondents patronizing female sex workers (FSW) in ‘mainland China only’ or in ‘mainland China and other places’ were more likely to be inconsistent condom users (28 and 34%) than those patronizing FSW in ‘Hong Kong only’ (9.1%). A similar pattern was found for self-reported STD in the past 6 months (10.1 8.1 and 1.0% respectively). Patronizing FSW in mainland China was associated with a higher prevalence of self-reported STD (adjusted OR 4.16) independent of consistent condom use and other potential confounding factors including calendar year of survey age educational attainment HIV-related knowledge perceived efficacy of condom use for HIV/AIDS prevention number of female sex partners and the presence of a regular female sex partner in the past 6 months. Clients who had commercial sex both in mainland China and Hong Kong were more likely to use condoms in Hong Kong than in mainland China (paired OR 4.67 P

This study examined sexual practices among the female population in Hong Kong. A total of 2,076 women between 18 and 50 years were interviewed by using a computerized telephone survey method. Sexually active women (59.3%) were classified into the "Husband Only Group" (HOG, n = 1,005), the "Steady Boyfriend Only Group" (SBG, n = 192), and the "Higher Risk Group" (HRG, n = 35). Over 60% of the HRG members did not perceive condom use as an efficacious means for HIV/AIDS prevention. Within the HOG and SBG, 30.0% and 41.1% reported that they always used condoms (25.7% in the HRG). Condom use was often suggested by both men and women of the SBG, but was often initiated by the women only in the HRG. "Trust" and "lack of necessity" were common reasons for not using condoms. About 85% of the respondents would ask their partners to use condoms if they suspected their partners having engaged in commercial sex; however, only 75% would have the final control. The HRG members seemed to be less able to insist on using condoms (55.6%, OR = 0.41, p.05) and were more likely than the HOG to perceive some chance of contracting HIV (OR = 10.88, p.01). The prevalence of high risk behaviors among women in Hong Kong was not high; however, those at risk were often inconsistent condom users and they had weak control over condom use. Women in Hong Kong had low awareness of HIV-related risk.

To determine the accuracy with which 'frontline' hospital doctors interpret computed tomography brain scans.Retrospective study.University teaching hospital, Hong Kong.Medical and emergency room doctors.Accuracy in correctly identifying features of acute stroke on 18 computed tomography brain scans.Computed tomography brain scan images showing easily detectable haemorrhage and infarct were identified in 91% and 90% of scans, respectively; but difficult-to-interpret scans with subtle features of haemorrhage or infarct were only correctly identified in 46% and 45% of readings, respectively. More experienced doctors did not perform better than junior doctors (P=0.69; 95% confidence interval, -1.84 to 2.73) and the mean total score for doctors from the emergency department did not differ significantly from that of doctors from the medical department (P=0.57; 95% confidence interval, -2.98 to 1.67).Early signs of infarct and small bleeds on computed tomography brain scans are not well recognised by doctors, regardless of clinical exposure or seniority. Ineligible patients may be treated with thrombolytic therapy as a result of such computed tomography scan misinterpretation.

A new rapid urine test was developed to detect anti-Helicobacter pylori antibody in urine using the principle of immunochromatography. The accuracy of this test in the Chinese population remains to be defined.To evaluate a new rapid urine test for the diagnosis of H. pylori infection in the Chinese population.Eligible patients without previous treatment of H. pylori were recruited. In-house rapid urease test and histology were used as the gold standard. The rapid urine test (RAPIRUN H. pylori antibody) was performed and the results were compared with the gold standard.One hundred and twenty-three patients were eligible for analysis and 61 (50%) were H. pylori positive by the gold standard. The rapid urine test showed a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 96.7%, 95.2%, 95.2%, 96.7% and 95.9%, respectively. Results were obtained within 20 min and no special laboratory support was required.The rapid urine test by immunochromatography is highly accurate for the diagnosis of H. pylori infection in untreated Chinese patients.

Numerous serological tests for the detection of Helicobacter pylori infection have been developed. However, many perform poorly when evaluated in the Chinese population.To search for optimal serological tests for the detection of H. pylori infection in Chinese patients.Consecutive dyspeptic patients referred for upper endoscopy were recruited. During endoscopy, gastric biopsies were taken for the CLOtest and histological examination. Patients were then given a 13C-urea breath test. Sera were used to test for H. pylori infection, employing three commercial enzyme-linked immunosorbent assay kits (pylori DTect, HP IgG and GAP IgG). Results were compared with the gold standard defined by the CLOtest, histology and 13C-urea breath test.Among the 142 patients (47 male, 95 female; mean age, 49 years) recruited, 81 (57%) were H. pylori-positive, 57 (40%) were H. pylori-negative and four (3%) were defined to be indeterminate. Using a self-defined cut-off value after calculation, the best accuracies for the pylori DTect, HP IgG and GAP IgG tests were 97%, 91% and 80%, respectively.The pylori DTect test is an optimal serological test for the detection of H. pylori infection in Hong Kong Chinese patients. The HP IgG test may be used as an alternative.

A Lead Discovery Library of piperazine-2-carboxamide derivatives was produced for general screening. This paper discloses two novel solid phase synthetic routes used to produce 15,000 single compounds via the Irori directed sorting technique. Computational methods such as reagent clustering and library profiling were used to maximize reagent diversity and optimize pharmacokinetic parameters. The results of a four center pharmacophore analysis revealed the added diversity gained by using two independent synthetic routes.

A new nursing method named Inspiring Psychological Nursing was initiated and applied to 176 primigravida undergoing vaginal delivery from Jan. to Jun. 1994. 202 primigravida who received general medical care during vaginal delivery from Jan. to Jun. 1993 was served as control group. No significant differences were found between the two groups regarding to age, gestational weeks, times of pregnancy, fetal position and newborn's weight. However significant differences were found regarding the duration of the second stage of labor and incidence of newborn asphyxia. Primigravida in the control group usually delivered after 60 min. and carried a higher incidence of newborn asphyxia, being 6.7%. It's concluded that Inspiring Psychological Nursing could significantly improve pregnancy outcome.

Non-sulfated bile acid levels including cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), lithocholic acid (LCA), ursodeoxycholic acid (UDCA), five taurine conjugates, and five glycine conjugates in duodenal juice were measured in 50 Chinese infants with cholestasis to test their diagnostic value. All 17 with biliary atresia (BA) cases, 11 out of 26 neonatal hepatitis (NH) cases and one case with paucity of the interlobular bile duct were without detectable bile acids. In those NH patients with detectable bile acids, the major components were conjugated forms of CA and CDCA, which was similar to all 6 cases of the comparison group with other diseases. The minor bile acid components identified in them were glycine conjugated UDCA, free CDCA, free CA, and free and conjugated DCA. Only one patient with NH had taurine conjugated LCA. The mean total duodenal bile acid level in 15 patients with NH was significantly lower than that in the 6 patients of the comparison group. Most patients with NH had a CDCA/CA ratio of less than one, indicating that cholic acid is the predominant form in their bile. Glycine conjugated bile acids were the predominant bile acids present in 11 out of 15 patients with NH and 4 out of 6 of the comparison group patients. The results suggest that the detection of duodenal bile acids by a sensitive HPLC method is of limited value in making a differential diagnosis between BA and NH.(ABSTRACT TRUNCATED AT 250 WORDS)

The energy levels of two-electron atoms continue to provide rigorous tests of relativistic quantum theory, and of correlation effects within a multi-particle system. These interactions are determined perturbatively, with several approximations, and theoretical results often differ. It is critical to provide precise measurements of absolute wavelengths connecting these atomic energy levels to obtain a resolution of the precision of the different parts of such complex calculations.

Etude theorique de la diffusion des positons en utilisant la formule de Kubo. Determination d'une expression pour le temps de relaxation de l'interaction positon-phonon lors de la diffusion. Calcul de la vitesse de relaxation par la methode de la fonction de Green

An experiment has been conducted in which cesium atoms in the kinetic energy range 2–350 eV collide with phosphorus halides. Parent anions and fragments are formed. Molecular energies are obtained from threshold measurements. The electron affinites for PCl3, POCl3, PBr3, PCl2Br, PBr2Cl, and POCl2 are found to be 0.8, 1.4, 1.6, 1.5, 1.6, and 3.8 eV, respectively. The P–X bond energies for PCl3, POCl3, and PBr3 are 3.3, 3.5, and 2.6 eV, respectively.

The problem of the exact location of the Frattini subgroup 4>(G) of a generalized free product G = (A*B)H was first raised by Higman and Neumann [5]. Solutions to special cases of the problem can be found in [1], [2], [8], [9] and [10]. The purpose of this note is to extend the results of [2], [8], and to simplify the proof of Whittemore's theorem [10]. We also apply our result to give simple proofs of certain classes of knot groups that have trivial Frattini subgroups. The proof that every knot group has trivial Frattini subgroup hard and long (footnote 2, p. 56).

An experiment is described in which cesium atoms, with kinetic energies in the range 10–350 eV, collide with CO2, CS2, and COS. The measured products are negative ions from charge exchange (NICE). The parent anions, CO2−, CS2−, and COS− are observed, as are other fragment ions. Intensity ratios for the various anions are measured as a function of cesium atom energy. The electron affinity of CO2, determined from crude threshold measurements, lies in the range −2.1 to −1.1 eV, with a precision of about ±0.25 eV.

Expression are obtained for the frequency dependence conductivity tensor in the presence of a magnetic field and hole-phonon interaction for p-type single quantum well structures. From this one obtains the information about the transport and optical properties of single quantum well structures. The [4 × 4] Luttinger-Kohn type of Hamiltonian is used to calculate Landau levels and Landau wave functions. Linear response theory is used to calculate the conductivity tensor and Green's function method is used to calculate the relaxation time (or Landau level broadening) due to hole-phonon interaction. The [4 × 4] matrix interaction Hamiltonian is considered for the hole-phonon interaction which includes the effects of internal strains arising from the mismatch of lattice constant or other defects. Selection rules Δn = ±3, Δn = ±1, are found and their corresponding probability amplitudes are obtained. Dispersional relations for magnetoplasma waves and elementary excitation are also given. Es wird ein Ausdruck fur den frequenzabhangigen Leitfahigkeitstensor im Magnetfeld und Loch-Phononwechselwirkung fur p-leitende Quantengrabenstrukturen erhalten. Daraus werden Informationen uber Transport- und optische Eigenschaften von Ein-Quantengrabenstrukturen erhalten. Der [4 × 4]-Luttinger-Kohn-Hamiltonoperator wird benutzt, um die Landauniveaus und Landauwellenfunktionen zu berechnen. Lineare Responsetheorie wird benutzt, um die Relaxationszeit (oder Landauniveauverbreiterung) infolge Loch-Phonon-Wechselwirkung zu berechnen. Der [4 × 4]-Matrix-Wechselwirkungshamiltonoperator fur die Loch-Phonon-Wechselwirkung wird berucksichtigt und schliest die Einflusse von inneren Spannungen aus der Fehlanpassung der Gitterkonstante oder anderer Defekte ein. Auswahlregeln Δn = ±3 und Δn = ±1 werden gefunden und ihre entsprechenden Wahrscheinlickeitsamplituden werden erhalten. Dispersionsbeziehungen fur Magnetoplasmawellen und Elementaranregungen werden ebenfalls angegeben.

We have developed a theory for positron diffusion in the presence of positron--acoustic-phonon interaction in semiconductors. Our treatment of the positron--acoustic-phonon interaction is based on an analogy with hole--acoustic-phonon interaction in contrast to existing theories which are based on electron--acoustic-phonon interaction. We treat the positron--acoustic-phonon interaction on the basis of the deformation-potential approximation and calculate the relaxation rate by using a self-consistent Green's-function method. We find that transverse phonons play a very important role in the diffusion process, along with the longitudinal phonons. This effect is not predicted by previous theories. The present theory is applied to calculate positron--acoustic-phonon relaxation rates and diffusion coefficients for Si, Ge, and GaAs. We find that the contribution of transverse phonons to the diffusion coefficient depends on the deformation-potential constants and also on the type of semiconductor, but is almost independent of temperature.

Analysis of reports in the world's literature suggests that average sperm densities for groups of unselected males were relatively constant at about 108 million cells per ml prior to 1950. Subsequent to that time mean sperm densities appear to have declined. Regression analysis indicates the existence of significant negative correlations between mean sperm densities and production of synthetic organic chemicals among other parameters. Phthalate esters are one class of large volume organic chemicals that are known to disturb testicular function in laboratory animals. These compounds are also the most abundant man-made chemicals in the environment. Plots of the concentration of dibutylphthalate in the cellular fraction of ejaculates against either the sperm density or the total number of sperm for the same ejaculates gave two clusters of points. These clusters suggest the existence of two or more populations vis à vis phthalate metabolism; both of which show a negative correlation between phthalate concentration and sperm production.

Negative ions are produced in a single-collision charge-transfer source. A beam of cesium atoms with kinetic energies which are variable between 10 and 350 eV intersects a beam of target molecules. Negative ions and Cs + are formed. The energy dependence of these anion spectra are measured for SO 2 , CH 3 NO 2 , SF 6 , and CF 2 Cl 2 . The observed cesium impact spectra are qualitatively different from those produced by electrons. At the higher cesium-atom energies, they are relatively insensitive to energy. Large parent ion intensities are seen for SO 2 and CH 3 NO 2 . For Cs + SF 6 , our ratios (SF 6 − /SF 5 − ) and (F − /SF 5 − ) are in agreement with those of Compton and Cooper for the limited range of Cs energy employed in both experiments.

A beam-gas method is described for measuring the fraction, f*, of laser-excited atoms in fast Na beams. The laser and atom beams are collinear. The technique is applied to beams in the energy range 1000-5500 eV, but has potential for energies outside this range. The measurements are based on ion-pair production from collisions of ground-state Na and I2. Since ion pairs are not produced with excited Na, the f* can be determined from measurements with the laser on and off.

Studies were made by a merging‐beams technique of the associative ionization (AI) reaction (1) Ne*+Ar*→NeAr++e and the Penning ionization (PI) reactions (2) Ne*+Ar*→Ne+Ar++e and (3) Ne*+Ar*→Ne++Ar+e. The relative kinetic energy of the reactants was varied from 0.01 to 10 eV. The Ne* and Ar* each represents a composite of the metastable 0P2,0 states. There is a complication in the present investigation which arises because AI and PI occur in collisions of Ne* with ground‐state Ar. Since the reactant beams consist of metastable as well as ground‐state species, the measurements are composites of chemi‐ionization in both the Ne*–Ar* and Ne*–Ar systems. Information on AI and PI for the Ne*–Ar* system is obtained by subtracting from these composite measurements known contributions of the Ne*–Ar system. From such information it appears that the molecular states of the reactants are different for reactions (2) and (3).

A crossed molecular beam apparatus is used to study the formation of anions by charge exchange of fast cesium atoms with a variety of halocarbons. The branching ratios are determined from threshold to 350 eV. Comparison of the spectator stripping and information theoretical models to the data leads to the conclusion that this class of reactions is an example of an ultradirect impulsive mechanism. In the most favorable case, that of CF3I, we have determined the near threshold relative cross sections for the anions CF3I−, I−, CF−3, and IF−. From these we determine the electron affinity of CF3I− to be 1.4±0.2 eV and the bond dissociation energy of CF3‐I− as 0.38±0.1 eV, which disagrees with values obtained in a previous experiment.

Measurements of the velocity dependence of the total ionization cross section of argon, krypton, and xenon on impact of thermal‐energy metastable neon (Ne*) atoms have been made using a velocity‐selected beam of the metastable atoms. The composition (3P2/3P0 ratio) of the Ne* atomic beam has been measured using an inhomogeneous‐field deflecting magnet and found to be about 5/1, assuming equal detection efficiency for the two metastable species. The ionization measurements were of sufficient precision to allow simultaneous determination of both the secondary‐electron‐ejection efficiency and the cross section. The secondary‐electron‐ejection efficiency from an argon‐covered gold surface on impact of metastable neon atoms was found to be 0.27± 0.14. In the relative velocity range investigated (g=320–1700 m/sec) the cross section Q was found to vary as g−m below g=650 m/sec and to rise at higher relative velocities. The value of m obtained is 0.622 for Ne*–Ar, 0.728 for Ne*–Kr, and 0.874 for Ne*–Xe. A simple ...

The dependences of the nonreactive scattering of potassium atoms at thermal energies from SF6, CCl4, and SnCl4 on internal energy of the molecules and initial relative kinetic energy are studied as a function of scattering angle. A collimated, velocity‐selected beam of potassium atoms is crossed at right angle with a molecular beam whose source temperature is varied over the range of 300°–580°K. The angular dependence of the nonreactive cross sections is analyzed with an optical model of chemical reactions to obtain information about potential parameters in an assumed form of two‐body interaction, the threshold conditions for reaction, the probability of reaction as a function of the distance of closest approach and internal energy, as well as an estimate of the total reaction cross section. The threshold conditions, energy and distance, in the reaction K + SF6 are independent of the initial relative kinetic energy at both low and high SF6 temperatures; the threshold distance increases by about 6% from T(SF6) = 300°K to 580°K. The variation of the nonreactive scattering with the SF6 beam source temperature, or SF6 internal excitation, can best be explained by a model in which only the stretching vibrational modes of SF6 are assumed to have an effect on the reactivity with K. The calculated differential cross sections based on this model fit very well to the measured results over the experimental ranges of SF6 temperature and of initial relative kinetic energy (2.05–5.18 kcal/mole). The effect of internal energy in CCl4 on its reactivity with K is similar to that of SF6 but smaller. The effect in SnCl4 is very small and uncertain; the interpretation is complicated by the lack of knowledge about the interaction potential.

In [1] Higman and Neumann asked the questions whether the Frattini subgroup of a generalized free product can be larger than the amalgamated subgroup and whether such groups necessarily have maximal subgroups. In [4] Whittemore gave answers to the special cases of generalized free products of finitely many free groups with cyclic amalgamation and of generalized free products of finitely many finitely generated abelian groups. In this paper we shall study the Frattini subgroups of generalized free products of any groups with cyclic amalgamation.

A two-state; impact parameter model is developed to provide a comprehensive description of Penning and associative ionization. It is used to fit recent experimental results at low velocities and to predict branching ratios. The model indicates that the interaction leading to ionization is short-ranged.

Raman bands originating from solvated SCN- anions and from Na+SCN- ion-pairs in solutions of NaSCN in N, N-dimethylacetamide (DMA) have been detected. Integrated Raman band intensities have been measured and the distribution of the concentrations of free and bound ligand and hence the stability constant have been obtained. Ultrasonic relaxation spectra at t=25°C, in the frequency range 3 to 350 MHz, show a single Debye relaxation for NaSCN, NaNO3 and NaNO2 solutions. These kinetic data have been interpreted in terms of the Eigen theory by employing the appropriate information derived from the Raman spectral study.