Laboratory confirmation of C60(+) as the carrier of two diffuse interstellar bands.

The diffuse interstellar bands are absorption lines seen towards reddened stars. None of the molecules responsible for these bands have been conclusively identified. Two bands at 9,632 ångströms and 9,577 ångströms were reported in 1994, and were suggested to arise from C60(+) molecules (ref. 3), on the basis of the proximity of these wavelengths to the absorption bands of C60(+) measured in a neon matrix. Confirmation of this assignment requires the gas-phase spectrum of C60(+). Here we report laboratory spectroscopy of C60(+) in the gas phase, cooled to 5.8 kelvin. The absorption spectrum has maxima at 9,632.7 ± 0.1 ångströms and 9,577.5 ± 0.1 ångströms, and the full widths at half-maximum of these bands are 2.2 ± 0.2 ångströms and 2.5 ± 0.2 ångströms, respectively. We conclude that we have positively identified the diffuse interstellar bands at 9,632 ångströms and 9,577 ångströms as arising from C60(+) in the interstellar medium.

Perspective: C60+ and laboratory spectroscopy related to diffuse interstellar bands.

In the last 30 years, our research has focused on laboratory measurements of the electronic spectra of organic radicals and ions. Many of the species investigated were selected based on their potential astrophysical relevance, particularly in connection with the identification of appealing candidate molecules for the diffuse interstellar absorptions. Notably, carbon chains and derivatives containing hydrogen and nitrogen atoms in their neutral and ionic forms were studied. These data could be obtained after developing appropriate techniques to record spectra at low temperatures relevant to the interstellar medium. The measurement of gas phase laboratory spectra has enabled direct comparisons with astronomical data to be made and though many species were found to have electronic transitions in the visible where the majority of diffuse bands are observed, none of the absorptions matched the prominent interstellar features. In 2015, however, the first carrier molecule was identified: C60+. This was achieved after the measurement of the electronic spectrum of C60+-He at 6K in a radiofrequency ion trap.

The ultraviolet photodissociation of CS2: the S(1D2) channel.

The photodissociation of CS(2) has been investigated using velocity-map ion imaging of the S((1)D(2)) atomic photofragments following excitation at 193 nm and at longer wavelengths close to the S((1)D(2)) channel threshold. The experiments probe regions both above and below the energetic barrier to linearity on the (1)Σ(u) (+)((1)B(2)) potential energy surface. The imaging data in both regions indicate that the electronic angular momentum of the S((1)D(2)) atom products is unpolarized, but also reveal different dissociation dynamics in the two regions. Excitation above the barrier to linearity yields an inverted CS((1)Σ(+)) vibrational population distribution, whereas the long-wavelength state-to-state results following excitation below the barrier reveal CS((1)Σ(+))(v, J) coproduct state distributions which are consistent with a statistical partitioning of the energy. Below the barrier, photofragment excitation spectra point to an enhancement of the singlet channel for K = 1, relative to K = 0, where K is the projection of the angular momentum along the principal axis, in agreement with previous work. However, the CS cofragment product state distributions are found to be insensitive to K. It is proposed that dissociation below the barrier to linearity occurs primarily on a surface with a significant potential energy well and without an exit channel barrier, such as that for the ground electronic state. However, oscillatory structure is also observed in the kinetic energy release distributions, which is shown to be consistent with a mapping of parent molecule bending motion. This could indicate the operation of competing direct and indirect dissociation mechanisms below the barrier to linearity.

A complete quantum mechanical study of chlorine photodissociation.

A fully quantum mechanical dynamical calculation on the photodissociation of molecular chlorine is presented. The magnitudes and phases of all the relevant photofragment T-matrices have been calculated, making this study the computational equivalent of a "complete experiment," where all the possible parameters defining an experiment have been determined. The results are used to simulate cross-sections and angular momentum polarization information which may be compared with experimental data. The calculations rigorously confirm the currently accepted mechanism for the UV photodissociation of Cl(2), in which the majority of the products exit on the C(1)Π(1u) state, with non-adiabatic couplings to the A(3)Π(1u) and several other Ω = 1 states, and a small contribution from the B(3)Π state present at longer wavelengths.

The vibrationally mediated photodissociation of Cl2.

The photodissociation of vibrationally excited Cl(2)(v = 1) has been investigated experimentally using the velocity mapped ion imaging technique. The experimental measurements presented here are compared with the results of time-dependent wavepacket calculations performed on a set of ab initio potential energy curves. The high level calculations allow prediction of all the dynamical information regarding the dissociation, including electronic polarization effects. Using a combination of theory and experiment it was found that there was negligible cooling of the vibrational degree of freedom of the parent molecule in the molecular beam. The results presented are compared with those following the photodissociation of Cl(2)(v = 0). Although the same electronic states are found to be important for Cl(2)(v = 1) as for Cl(2)(v = 0), significant differences were found regarding many of the observables. The overall level of agreement between theory and experiment was found to be reasonable and confirms previous assignments of the photodissociation mechanism.

Electronic polarization effects in the photodissociation of Cl2.

Velocity mapped ion imaging and resonantly enhanced multiphoton ionization time-of-flight methods have been used to investigate the photodissociation dynamics of the diatomic molecule Cl(2) following excitation to the first UV absorption band. The experimental results presented here are compared with high level time dependent wavepacket calculations performed on a set of ab initio potential energy curves [D. B. Kokh, A. B. Alekseyev, and R. J. Buenker, J. Chem. Phys. 120, 11549 (2004)]. The theoretical calculations provide the first determination of all dynamical information regarding the dissociation of a system of this complexity, including angular momentum polarization. Both low rank K = 1, 2 and high rank K = 3 electronic polarization are predicted to be important for dissociation into both asymptotic product channels and, in general, good agreement is found between the recent theory and the measurements made here, which include the first experimental determination of high rank K = 3 orientation.

Velocity map imaging in time of flight mass spectrometry.

A new variation on time of flight mass spectrometry is presented, which uses a fast framing charge coupled device camera to velocity map image multiple product masses in a single acquisition. The technique is demonstrated on two photofragmentation processes, those of CS(2) and CH(3)S(2)CH(3) (dimethyldisulfide) at a photolysis wavelength of 193 nm. In both cases, several mass fragments are imaged simultaneously, and speed distributions and anisotropy parameters are extracted that are comparable to those obtained by imaging each fragment separately in conventional velocity map imaging studies.

Fertility, family size preferences and future fertility prospects of men in the western area of Sierra Leone.

This paper examines the current fertility of men and women in the Western area of Sierra Leone and the prospects for future fertility behaviour. Probably due to the effect of rapid economic decline in Sierra Leone since 1980, the desired family size has fallen. But indications are that the preferred completed family size is lower than the desired family size.

PIP: Between December, 1986, and February, 1987, interviews were conducted among 3006 ever married men and 539 currently married women living in the western area of Sierra Leone to determine current fertility and possibility of future fertility of men. The researchers included the women to check on consistency using interspouse responses. The men's ideal family size was greater than desired family size (5.6 children vs. 4.4 children). Except for men with secondary education, the desired family size was always 1 child more than the expected completed family size. The expected mean completed family size was lower than desired family size (4 children vs. 4.4 children; p .001). The men fathered a mean of 3.4 children. Men had significantly more children than did women (3.4 vs. 2.9; p .001). 38.2% did not want any more children, and 74.9% of them had at least reached their desired family size. 25.4% of men who wanted no more children were using contraceptives, presumedly to stop reproduction. The fact that about 30% of all men had a higher desired family size than actual family size suggested that they stopped reproduction earlier than planned due to a rationalization effect. 12.2% of the men in Greater Freetown and 13.3% of those in the western rural area were likely to complete their families before they reached their desired family size. Desired family size had a significant effect on future fertility behavior, accounting for 15% of the variation in Greater Freetown and for 12.3% in the western rural area. These findings suggest that fertility in western Sierra Leone will likely continue to decline.

Sex preferences for offspring among men in the western area of Sierra Leone.

This study reveals evidence of a significant sex preference among men. Programmes aimed at changing men's views on the importance of the sex of a child must be implemented in order to reduce the desired family size and eventual fertility.

PIP: In late 1986, researchers conducted a survey of 3006 ever married men 20 years and over in western Sierra Leone (80% from Greater Freetown and 205 from rural areas) to determine if sex preference exists among men. 52% wanted family composition to be equally divided between boys and girls. Yet 70% of both urban and rural men considered boys to have higher relative value than girls. In rural areas, when researchers disaggregated desired family size, son preference was only significant for men who wanted 5-7 children. In Greater Freetown, it was significant for all disaggregated family sizes 91-3, 5-7, 5+, and 8+ children). Sociocultural reasons provided the leading reason for preferring a boy (urban, 66.3%; rural, 66.7%). In a patrilineal society, the underlying preference for a boy consists of an intrinsic desire to continue the family name and have a male inheritor (urban, 27.6% and 30.6%; rural, 27.4% and 30.4% respectively). A son born to a woman not (or will not be) married to the father does not necessarily receive an inheritance, however. These reasons were not attributed to daughters, but if an only child is a female she does indeed inherit her father's assets. More men in the rural area expected help in old age from their sons (10.1%) rather than their daughters (6.1%), despite the fact that a popular proverb exists, especially among the Creoles, that sons are for the mother while the daughters are for the father. Even though contraceptive use stood at 20% for men and 22% for women, it was used for birth spacing and not to reduce fertility. In fact, the preference for sons contributed to present and future high fertility in the western area of Sierra Leone. Measures to change men's attitudes towards son preference are needed.

Male role in fertility decisions in Robertsport, Liberia: an experimental exercise for policy formulation.

There is a tendency to believe that in African societies men are the dominant decision makers in the family. In Robertsport, Liberia, there are indications that, with respect to fertility regulation, the dominance of the husband in fertility decisions exists, but it is also apparent that many of these decisions are made jointly by both husband and wife. Education is particularly influential in the joint fertility decision-making process. The 100 husbands sampled in 1982 desired a large number of children and had experience with infant and child mortality. If family planning programs should attain their goals, men should be more involved, than at present, in every aspect of the programs. Equally important is the urgency for studies related to the role of men in fertility regulation, using adequately large samples.

Family size preferences of men in the western area of Sierra Leone. Method and determinants.

PIP: A sample survey of the Western Area of Sierra Leone was conducted between November 1986 and February 1987 targeting ever married men aged 20 and over to gather data for the analysis. In Greater Freetown a cluster sampling method was employed. The enumeration areas (EAs) used for the 1985 national census were divided into 862 sub-EAs and a sample cluster of 40 sub-EAs was selected. A simple systematic random selection of 5 out of 15 EAs in the Western Rural Area was performed, and a total of 3006 men were enumerated. Data analysis was based on cross-tabulations and multiple regression. The one-way analysis of variance (ANOVA) was used to test for differences between means and the relationship between response and dependent variables. The step-wise regression method was used in order to screen out redundant variables where multicollinearity occurs. Over 90% of the sampled men in the Western Area were currently married, and almost 9% were either separated or divorced. The mean age was 40.3 years in Greater Freetown, while in the Western Rural Area it was 41.8 years. The mean ages at first marriage for men in the city and Western Rural Area were 26.5 years and 26.4 years, respectively. Over 95% of men in the Western Area were familiar with both traditional and modern contraceptives, while only 76.7% knew modern contraceptives alone. However, only 26.5% used modern contraceptives. 41.3% of men used the condom whenever they had to resort to protection. Oral contraceptives (30%), the IUD (14.3%), foaming tables and jelly (11.9%) followed in popularity. The mean desired family size was 4.39 children in the Western Area, 4.97 in the Western Rural Area, and 4.27 in the city. In the city as well as in the Western Rural Area the sociopsychological factor was most influential in determining men's desired family size (51.1% and 50.6%, respectively). The current status of the economy's effect on men's desired family size was the most important determinant.^ieng

Male role in fertility decisions in Robertsport, Liberia.

"This paper examines the role of men in family planning among the Vai tribe in Robertsport, Liberia. The data were collected from a sample survey of Vai males in the town in 1982." The author found in a sample of 100 married men aged 15-39 that husbands, generally desiring large numbers of children, are a dominating influence in fertility decisions. In decisions that are reached jointly, educational attainment appears to be a significant factor.

Mortality levels in Liberia and policy implications: an application of the census survival ratio method.

PIP: Recent mortality estimates have indicated life expectancy in Liberia to be nearly 50 years, a figure much higher than that of neighboring countries. It is the author's belief that Liberian mortality has been understated. Therefore, in this study the census survival ratio method is applied to data from the official Liberian censuses of 1962 and 1974 for the purpose of obtaining more plausible mortality estimates for the decade between 1964 and 1974. The method does yield satisfactory mortality estimates, suggesting a life expectancy of 35-40 years. In view of the fact that mortality is shown to be high, the author proposes some measures that would be useful in lowering the mortality rate, especially among infants and children.^ieng

Family size and sex preferences and eventual fertility in Botswana.

Botswana is one of the sub-Saharan countries where actual fertility has declined. This study examines the fertility preferences of both men and women and shows that fertility intentions have a significant influence on future fertility behaviour. Fertility preferences are relatively low and there is no significant difference between those of men and women. Men's preference for sons influences desired family size and eventual fertility. For women as well as men, child survival is an important factor. Women's income is also influential.

PIP: This study examines the relationship between fertility desires and eventual fertility and the effect of sex preferences and education. Data were obtained from a sample of 1047 men and 1186 women during June-August 1992 in three districts and in Gaborone, the capital city. There was a strong correlation between family size and number of surviving offspring. The mean desired family size was 3.1 children in 1992 compared to 4.7 in 1988. On average, women desired more children than men, but differences were not significant. Being born in an urban center for men or women was related to significantly lower fertility intentions than being born in a rural area. Marital status and income had a significant influence on women's desired family size. Men's fertility intentions were not significantly influenced by education, income, and marital status. Desired family size for women was significantly influenced by the value placed on children. Multiple regression analysis reveals that 4 of the 16 predictors explained 21.1% of variance in men's fertility intentions; 7 predictors accounted for 35.1% of the variance in women's fertility intentions. Son preference explained 10.3% of the variance. Daughter preference explained 3.8% of the variance in desired family size. 4.9% of the variance in men's desired fertility was explained by preferred completed family size. 12.4% of the variance in women's desired fertility was explained by preferred completed family size. 5 predictors explained 71.7% of men's preferred completed family size in Model 1; 4 predictors for women explained 78.5% of preferred completed family size. Son preference was a strong predictor for men in both models. Findings suggest that fertility decline increased son preference among men. Men's desire for sons increased after fathering one or two daughters. Women's preference for sons was related to the sex preference of men in general. Son preference is not expected to stop fertility decline in Botswana.

Social behavior correlates of cortisol activity in child care: gender differences and time-of-day effects.

The relations between social behavior and daily patterns of a stress-sensitive hormone production were examined in preschool children (N = 75) attending center-based child care. Three behavioral dimensions, shy/anxious/internalizing, angry/aggressive/externalizing, and social competence, were assessed by teacher report and classroom observation, and their relations with 2 measures of cortisol activity, median (or typical) levels and reactivity (quartile range score between second and third quartile values) were explored. Cortisol-behavior relations differed by gender: significant associations were found for boys but not for girls. Specifically, for boys externalizing behavior was positively associated with cortisol reactivity, while internalizing behavior was negatively associated with median cortisol. Time of day of cortisol measurement affected the results. Surprisingly, median cortisol levels rose from morning to afternoon, a pattern opposite to that of the typical circadian rhythm of cortisol. This rise in cortisol over the day was positively correlated with internalizing behavior for boys. The methodological and theoretical implications of these findings for the study of the development of hormone-behavior relations are discussed.