Investigation of ion dynamics of laser ablated single and colliding carbon plasmas using Faraday cup

We report a comparative study of a single plasma and a colliding laser produced plasma, investigated using a Faraday cup. An enhancement in ion emission and stagnation is observed in colliding plasma plume compared to single plasma plume. We observed that fast ion generation in laser ablated plasma can be achieved at large laser intensity on to the target. As laser intensity increases ionic yield increases for both colliding and single plume and at a fixed laser intensity ionic yield decreases with increase in ambient pressure. The double peak structure is observed in the ion signal at large fluence where the peaks correspond to fast and slow species. A Faraday cup composed of nine collectors is used to measure the spatial/angular distribution of ion of expanding plasma plume. Ionic yield is found to be larger in the colliding plasma plume than the single plasma plume at all spatial/angular positions.

Watt-level single-frequency tapered amplifier laser using a narrowband interference filter

We demonstrate a tunable external cavity tapered amplifier laser (ECTAL) using a narrowband interference filter as the wavelength discriminator. The laser is tunable over a wavelength range from 1006 to 1031 nm with an output power of ∼1  W. The amplified stimulated emission of the laser system is suppressed to better than 32 dB. The laser is applied to study the saturation spectroscopy on the R(39) 57-0 line of iodine molecule, which, to our best knowledge, is the first measurement of this line close to the dissociation limit. The linewidth of the a₁ component is ∼2  MHz at the iodine vapor pressure of ∼11  Pa, and the pressure-broadening coefficient is ∼156  kHz/Pa. This laser system is also used for the injection seeding of a 1030 nm disk laser to perform hyperfine spectroscopy of muonic hydrogen. To reach a satisfactory condition for disk laser use, the ECTAL is successfully stabilized to the iodine Doppler-free spectroscopy of the P(26) 43-0 line near 515 nm, with continuous locking over 48 h.

A rare presentation of a transethmoidal encephalocele at birth

Transethmoidal encephalocele is a very rare condition. Herein, we report the case of a neonate with a transethmoidal encephalocele, who presented with an externally visible intranasal mass at birth. Clinical suspicion of intracranial extension was confirmed by radiological imaging. A bifrontal craniotomy was done to divide the narrow communicating duct. The mass was delivered through the nostril and duraplasty was completed. The postoperative recovery was uneventful.

Stoichiometry of laser ablated brass nanoparticles in water and air

We report on the stoichiometric analysis of laser ablated brass plasma nanoparticles (NPs) in water and ambient air. Morphological study of the deposited NPs in water showed smaller spherical NPs compared to micrometer sized spherical particles in air. The smaller particles were Zn enriched and the concentration decreased with increases in size. Photoluminescence of particles at 380 nm corresponding to ZnO showed higher concentrations of Zn with smaller sized deposited NPs, whereas the micrometer sized particles showed multiple peaks at 415 and 440 nm, which implied that there was an abundance of the Cu fraction in the NPs. Plasma plume parameters, electron temperature, electron density, and evolution of the plasma plume were studied using optical emission spectroscopy and 2-dimensional imaging of the plume. The mass ablation rate in water was observed to be greater than that in air. Higher electron density and temperature of the plasmoid in water was attributed to confinement of the plasma plume near the target surface in water.

Stoichiometric investigations of laser-ablated brass plasma

Laser-ablated brass plasma plumes expanding in various air pressures have been studied using optical emission spectroscopy and two-dimensional imaging. The velocity of the plume front calculated from the R-t plot decreases from 1.9×10(4) m/s to ~5.5×10(3) m/s as the pressure increases from 0.01 to 10(5) Pa. The estimated higher electron temperature for Cu I (510.5 nm) transition than for Zn I (481.1 nm) may be due to differences in the heat of vaporization and vaporization temperature of copper and zinc. The electron density estimated using the Stark-broadened transition 4p(2)P(3/2)→4s(2)(2)D(5/2) of Cu I (510.5 nm) is about 10 times higher than that for transition 4s5s(3)S(1)→4s4p(3)P(2) of Zn I (481.1 nm). The appearance and enhancement of the Cu(2) (A-X) band at lower ambient pressure and formation of nanoparticle clusters have been extensively discussed. Stoichiometric and morphological study of the deposited nanoparticles on carbon tape at different ambient pressure reveals a different percentage composition of copper and of nanoparticles.

Anal shift: preliminary results

BACKGROUND/PURPOSE

Perineal ectopic anus in female infants is not a very uncommon congenital anomaly. The close proximity of the ectopic anus with the vulva and the stenosed opening seen in large majority of cases necessitate some form of surgical correction. A variety of surgical procedures like cutback, posterior anal transposition, PSARP, or ASAPR, with or without diverting colostomy have been described in the literature. However, in dealing with a case of ectopic anus, the authors thought a much simpler surgical correction would suffice giving an aesthetically and functionally acceptable perineum. This new and simple surgical procedure developed by Ashok Shah, Anal Shift is described in this report.

METHODS

Twelve female infants with anterior ectopic anus, between 3 and 18 months of age who had undergone surgical correction by this new method (Anal Shift) is reported. Five of these children had severe and 2 had mild anal stenosis. The new technique described in detail includes shifting and creation of a new anus in the anatomically normal site and construction of the perineal body. Colostomy was not done in any of them.

RESULTS

The cases had been followed up for 12 to 24 months. Anal function was normal with satisfactory vulvo-anal distance without any stenosis. One patient had superficial anterior wound dehiscence; she underwent reoperation with good results.

CONCLUSIONS

Anal Shift is a simple surgical procedure. It does not necessitate lateral dissection, therefore, the rectal support and the neurovascular supply to the rectum remains undisturbed, eliminating any chance of retraction. The anterior half of the neoanus does not have a suture line, thereby minimizing the chances of stricture formation. Anal Shift appears to be a safe, simple and satisfactory surgical procedure to correct anterior ectopic anus in girls without a colostomy.

Photon-avalanche upconversion in thulium-doped lutetium aluminum garnet

Strong blue fluorescence at 487 nm corresponding to the (1)G(4) --> (3)H(6) transition was generated from Tm(3+)-doped lutetium aluminum garnet on excitation with a 618-nm dye laser as a result of a photon-avalanche upconversion mechanism.

Diode-Pumped Violet Energy Upconversion in BaF(2):Er(3+)

Under 805-nm diode-laser excitation we detected intense upconversion signals at 410, 380, and 275 nm in BaF(2):Er(3+). Energy upconversion schemes and efficiencies are discussed in detail. Intensity parameters of Er(3+) in BaF(2) were derived as Omega(2) = 1.048 ? 0.117 x 10(-20) cm(2), Omega(4) = 1.478 ? 0.180 x 10(-20) cm(2), and Omega(6) = 1.009 ? 0.127 x 10(-20) cm(2).

Ethnic differences in bone density in female South African nurses

In the United States, the higher prevalence of osteoporosis and the higher incidence of fractures in whites than in blacks may be attributed to the finding of lower bone density (BD) in both white children and adults. In South Africa, osteoporosis and fractures also occur more frequently in whites than in blacks. Appendicular BD has been found to be similar in black and white children in South Africa, but there is little information available on BD of adults in South Africa. This cross-sectional study aimed to assess changes in BD with age in adult females in South Africa and to assess possible differences in peak BD and in the rate of postmenopausal bone loss between blacks and whites. Data for 180 black and 184 white female nurses aged 20-64 years were analyzed. The distal radius bone density (RBD) was measured by single photon absorptiometry. The lumbar spine bone density (SBD) and the femur bone density (FBD) were measured by dual-energy X-ray absorptiometry. Blacks were shorter than whites (p = 0.0001), and blacks' weight, body mass index, and skinfold thickness increased with age. Peak SBD and RBD were similar in blacks and whites, but peak FBD was higher in blacks (p = 0.0001). This ethnic difference in peak FBD became apparent in the fourth decade. Peak FBD was similar in black and white subjects with normal body mass indices (p = 0.09), but in overweight subjects peak FBD was higher in blacks than in whites (p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ethnicity on appendicular bone mass in white, coloured and Indian schoolchildren

Ethnic differences in the incidence and prevalence of osteoporosis have been shown throughout the world. In South Africa the prevalence of osteoporosis is much higher in whites than in blacks. This is surprising, since factors that might predispose to reduce bone mass are more preponderant in black communities. The present research was undertaken to determine whether differences in bone mass during the period of bone accretion could explain the difference in the incidence of osteoporosis. In this paper we report on differences in appendicular bone mass between white, coloured and Indian children and teenagers (6-18 years) from Johannesburg. The effects of weight, height, puberty and skinfold thickness on bone mass were also assessed. The bone width (BW) of white boys was greater than that of Indian boys, while the bone mineral content (BMC) and BMC/BW were greater in white boys than in both Indian and coloured boys. After adjustment for differences in weight and height, the BW of coloured boys was significantly greater than that of white boys, while all differences in BMC and BMC/BW became non-significant. For girls there were no significant differences in bone mass measurements, but after adjustment for height and weight coloured girls had significantly greater BMC and BMC/BW than either white or Indian girls. This greater weight- and height-adjusted bone mass in coloured girls is consistent with the impression of a lower incidence of osteoporosis in coloured women than in white women.

The effect of ethnic group on appendicular bone mass in children

The prevalence of senile and postmenopausal osteoporotic fractures is considerably higher in white than black women. Although the reasons for the genetic difference have not been elucidated, it has been suggested that ethnic differences in peak bone mass may be partially responsible. The present study examined appendicular bone mass (single-photon absorptiometry, SPA) in black and white children between the ages of 6 and 20 years. The sample was stratified for ethnic group, age, and sex. The effect of weight, height, puberty, and skinfold thickness on bone mass was also assessed. The bone width (BW) and bone mineral content (BMC) of males were significantly higher than those of females (p less than 0.0001). There were no statistically significant differences in bone mineral content normalized for bone width (BMC/BW) between the sexes (p = 0.1743 for whites and p = 0.5456 for blacks). The bone mass parameters of black girls were generally lower than those of white girls. After adjusting for height, BMC and BMC/BW of black girls tended to be greater than those of white girls (unadjusted p = 0.0258 for BMC and p = 0.0340 for BMC/BW). White boys tended to have greater bone mass parameters than black boys. After adjusting for height the trends disappeared. Thus, unlike the studies of bone mass in adults from the United States, we were unable to show that age-matched black children have higher bone mass than whites. After adjusting for height, however, the bone mass of black children (especially black girls) was marginally, but not significantly, greater than that of white girls.

The effects of mesterolone on sperm count in idiopathic oligospermia

Forty subfertile men with idiopathic oligospermia were randomly treated with mesterolone or with placebo for more than 4 months. Seminal analysis was performed thrice before treatment, and twice after 16 weeks of treatment. There was a significant increase of semen volume (P less than .05), mean sperm concentration (P less than .01), and mean total sperm count per ejaculate (P less than .01) with mesterolone therapy. Sperm motility and morphological characteristics were not modified by mesterolone therapy. Mesterolone was found to be effective in improving the sperm concentration in mild and moderate rather than in severe idiopathic oligospermia.

Fertility after chemotherapy for testicular cancer

Sixty-nine patients with disseminated testicular cancer and no prior retroperitoneal lymphadenectomy treated with cisplatin, vinblastine, and bleomycin with or without doxorubicin were evaluated for semen analysis, serum gonadotropins, and testosterone. Since 1979, 41 men have been prospectively studied. Before treatment 77% were oligospermic, 17% were azoospermic, and only 6.6% could meet requirements for sperm banking. After 2 mo of therapy, 96% were azoospermic. A group of 28 patients treated between 1975 and 1979 were retrospectively evaluated. Normal sperm counts were found in 46% of those studied. Only 17% were azoospermic. Thirty-two percent have impregnated their wives, resulting in 5 healthy babies, 1 spontaneous abortion, and 3 ongoing pregnancies. These results show that (1) significant impairment of spermatogenesis exists before therapy, precluding the possibility of sperm banking in most patients, (2) combination chemotherapy in testicular cancer has substantial effects on gonadal function, rendering almost all patients azoospermic, and (3) a high degree of recovery of spermatogenesis occurs sometime after 2-3 yr from the initiation of treatment.