Propagation of Gaussian Schell-model beams in modulated graded-index media.

The evolution of partially coherent beams in longitudinally modulated graded-index media is studied. The special cases of Gaussian Schell-model beams and parametric modulation, when the modulation period is half the fiber self-imaging period, are examined in detail. We show that the widths of the intensity and coherence of Gaussian Schell-model beams undergo amplification in parametrically modulated parabolic graded-index media. The process is an analog of quantum mechanical parametric amplification and generation of squeezed states. Our work may find application in spatial and temporal imaging of partially coherent beams in fiber-based imaging systems.

Resonance in quantum dot fluorescence in a photonic bandgap liquid crystal host.

Microcavity resonance is demonstrated in nanocrystal quantum dot fluorescence in a one-dimensional (1D) chiral photonic bandgap cholesteric-liquid crystal host under cw excitation. The resonance demonstrates coupling between quantum dot fluorescence and the cholesteric microcavity. Observed at a band edge of a photonic stop band, this resonance has circular polarization due to microcavity chirality with 4.9 times intensity enhancement in comparison with polarization of the opposite handedness. The circular-polarization dissymmetry factor g(e) of this resonance is ~1.3. We also demonstrate photon antibunching of a single quantum dot in a similar glassy cholesteric microcavity. These results are important in cholesteric-laser research, in which so far only dyes were used, as well as for room-temperature single-photon source applications.

Phase-locked laser system for use in atomic coherence experiments.

We describe a phase-coherent laser system designed for use in experiments involving coherently prepared atomic media. We implement a simple technique based on a sample-and-hold circuit together with a reset of the integrating electronics that makes it possible to scan continuously the relative frequency between the lasers of over tens of gigahertz while keeping them phase locked. The system consists of three external-cavity diode lasers operating around 795 nm. A low-power laser serves as a frequency reference for two high-power lasers which are phased locked with an optical phase-locked loop. We measured the residual phase noise of the system to be less than 0.04 rad(2). In order to show the application of the system towards atomic coherence experiments, we used it to implement electromagnetically induced transparency in a rubidium vapor cell and obtained a reduction in the absorption coefficient of 92%.

Prolactin variants in ram adenohypophyses vary with season.

Secretion of PRL in sheep is affected by photoperiod being highest during the spring and summer, lowest in fall and winter. The objectives of this study were to determine if 1) the production of variant forms of PRL, and 2) immuno- and bioactivities of PRL (iPRL and bPRL) differ during times of the year selected to represent periods of low, transitional and high PRL secretion. Twelve mature rams were maintained on pasture and killed in October, December, and April (n = 4/month). Individual pituitary glands were dispersed, cells obtained, and fixed for immunocytochemical flow cytometry, extracted with 0.01 N NaHCO3 or cultured in serum-free, defined media. The Mr of PRL extracted from cells immediately following dispersion ranged from 14-140K, with significantly more bands greater than 40K being detected from rams sacrificed in December than from those killed in October and April (P less than 0.01). No bands of PRL greater than 25K were observed when samples were reduced with beta-mercaptoethanol prior to electrophoresis, indicating that the high Mr forms were disulfide-linked aggregates. Culture media from October and April contained variants of PRL that ranged from 22-40K but those greater than 25K were generally not observed from cells harvested during December. Extracts of cells after 24 h in culture contained fewer high Mr species during December than had been present in initial extracts from that month. In contrast, during April more high Mr intracellular forms were present after culture than had been detected prior to culture during that month. The percentage of lactotrophs averaged 50.0 +/- 2.5, 47.4 +/- 5.7, and 59.4 +/- 5.5 for October, December, and April, respectively. Initial lactotroph content (pg/lactotroph) of iPRL was higher (P = 0.06) in April (46.0 +/- 17.0) when compared to October and December (8.0 +/- 2.0 and 20.0 +/- 10.0, respectively). In contrast, the bPRL content of initial extracts was higher (P = 0.05) in December (267.0 +/- 68.0) than in October (101.0 +/- 35.0), but not than in April (190.0 +/- 70.0). Although iPRL and bPRL concentrations in culture media were similar for the 3 months, the intracellular iPRL (P less than 0.001) and bPRL (P less than 0.0001) content after culture was greatest during April. In summary, in addition to the well-documented seasonal changes in blood concentrations of PRL, different molecular forms of PRL were found within the pituitary at different times of the year and seasonal variations in iPRL and bPRL did not occur in parallel.

Age-related changes in the secretion of growth hormone in vivo and in vitro in infantile and prepubertal Holstein bull calves.

The average concentration of GH in blood is high at birth and declines during the period of sexual maturation in bulls. The objectives of these studies were (1) to define age-related changes in vivo in the pulsatile secretion of GH from birth to puberty, (2) to determine whether pituitary cell content of GH and characteristics of the secretion of GH in vitro reflect age-related changes in vivo, and (3) to examine whether responsiveness to GH-releasing hormone (GHRH) and somatostatin (SRIF) in vitro changed with age in Holstein bull calves. In experiment 1, calves were bled every 15 min for 12 h at < 1, 12 and 42 weeks of age (n = 5/group), these being representative of infantile, juvenile and pubertal stages of development. Calves were killed 3 to 5 days later and the pars distalis of the anterior pituitary gland was enzymatically dispersed into a suspension of single cells. Aliquots of cells were extracted with 0.01 mol NaHCO3/l to determine the content of GH and cultured for 18 and 72 h. As expected, the average concentration of GH in plasma decreased with age (P < 0.001). The initial decrease in GH was caused by a reduction in the baseline concentration between birth and 12 weeks of age. There was a marked decrease in GH pulse amplitude between 12 and 42 weeks of age and a further reduction in the baseline concentration. In contrast, the pulse frequency of GH increased (P < 0.05) from < 1 week to 12-weeks of age and remained constant thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Visualization of the core-scattering dynamics of Rydberg wave packets.

We present classical and quantum studies of the scattering dynamics of Rydberg electron wave packets from the electronic core of alkali atoms. In quantum systems an ideal state for studying such effects is an angularly localized wavepacket in which the primary effect of the scattering is to cause precession. The scattering is enhanced by the application of an external dc electric field. We calculate and animate the field-induced dynamics of both hydrogenic and alkali wavepackets and compare them to classical atomic models. We end that in alkali systems the scattered wave function can be divided into two components: one whose nearly hydrogenic behavior is due to quantum interference near the core, and another which exhibits the orbital precession found in classical models of nonhydrogenic atoms.

Shaping an atomic electron wave packet.

We consider coherent control of the shape of an atomic electron's wavefunction using a train of short transform-limited laser pulses. This type of control is experimentally demonstrated by exciting with a train of three pulses and measuring the resulting quantum state distribution. We also present a general theory for control with a train of N pulses in the weak field limit and discuss the extension of this theory to the strong field limit.

Analysis of antibody-dependent cell-mediated cytotoxicity in autoimmune thyroid disease.

There is no consensus on the role of antibody-dependent cell-mediated cytotoxicity (ADCC) in autoimmune thyroid disease; recent reports have suggested that antibodies mediating ADCC are found particularly in patients with primary myxoedema, occur less frequently in Hashimoto's thyroiditis and are absent in Graves' disease. Using an ADCC assay with a single source of effector and target cells, and expressing results as lytic units, we have found antibodies capable of mediating ADCC in 9 of 17 patients with primary myxoedema, 9 of 22 patients with Hashimoto's thyroiditis and 6 of 22 patients with Graves' disease. There was no significant difference between the groups in this distribution. Mean levels of ADCC activity were not significantly different comparing primary myxoedema and Hashimoto's thyroiditis patients, although levels were lower in Graves' disease patients compared to those with Hashimoto's thyroiditis (P < 0.05). There was no correlation between TPO antibodies (total IgG or IgG subclasses) measured by ELISA and ADCC activity. These results suggest that thyroid antigens besides TPO are involved in ADCC and that antibodies mediating ADCC are not restricted to subgroups of patients with autoimmune thyroid disease.

Occurrence of infection with a parvovirus-like agent in children with sickle cell anaemia during a two-year period.

The occurrence of infection with a parvovirus-like agent during the period April 1979-May 1981 in children attending a single sickle cell clinic in London was investigated. Virus was detected in serum by counter-current immunoelectrophoresis (CIE) and immunoelectron microscopy (IEM). Viral antibody was detected by CIE and specific IgM antibody by an IgM-antibody capture assay. Of the 68 children studied nine presented in aplastic crisis and evidence of infection with the parvovirus-like agent at the time of the crisis was found in all nine. Eighteen of the other children were antibody-positive at some time during the study. In 11 children there was no evidence of recent infection; however, two of these had a history of aplastic crisis in previous years. The other seven seroconverted during the course of the study but did not show any haematological effects. Five of these had a primary infection, one appeared to have reinfection and in the seventh there were insufficient data to distinguish between the two. Possible explanations for the difference between those presenting with aplastic crisis and those with asymptomatic seroconversion are discussed.

Analysis of antibodies against components of the autonomic nervous system in diabetes mellitus.

Antibodies to autonomic nervous system structures have previously been detected using a complement fixation immunofluorescence test in the sera of patients with insulin-dependent diabetes mellitus (IDDM) and non-insulin dependent diabetes mellitus (NIDDM). These antibodies might play a role in the aetiology of autonomic neuropathy. Sera from 45 IDDM, 40 NIDDM and 52 control subjects were tested by immunofluorescence for antibodies to human sympathetic ganglia, human adrenal medulla and rabbit vagus nerve. The use of human sympathetic ganglia was compared with rabbit tissue for the detection of sympathetic ganglia antibodies; the results for these autonomic nervous system antibodies were also compared with results using an ELISA. There was no relationship between the presence of antibodies detected by ELISA and those detected by immunofluorescence, but of 14 IDDM patients with thyroid antibodies, 12 had autonomic nervous system antibodies detected by either immunofluorescence or ELISA (p < 0.005 compared to patients without thyroid antibodies). To further characterize the autoantigen(s), immunoblotting was performed. An adrenal antigen corresponding to 74 kDa was detected in sera from three patients, only one of whom had antibodies detectable by ELISA and immunofluorescence. One IDDM serum showed specific binding to a vagus nerve antigen corresponding to 33 kDa. No specific binding to sympathetic ganglia antigen was demonstrated. Antibodies against autonomic nervous system antigens are an inconsistent feature of diabetes, and appear more associated with coincidental autoimmunity against other organs such as the thyroid.

A paediatrician's view of the newborn baby and its epidermis.

Almost all babies born in the United Kingdom are born in hospital and with the continuing improvements in neonatal care more survive than ever before, particularly those of very low birth weight. The use of the manipulative and invasive procedures so necessary to monitor and assist their healthy development often result, however, in skin problems arising from intolerance of adhesives, perforating wounds, cleansing solutions, etc. In the older newborn infant, the main skin problems of the anal and neck regions, in particular, are usually associated with artificial milk feeding and inadequate drying of the skin. Many of the skin rashes seen in the newborn, although worrying, are of no consequence, but all those which are petechial or due to microbial infection require prompt investigation and adequate treatment. Despite the advances of recent years, there is still need for further research into procedures and products to ensure that the infant's protective yet delicate covering is disturbed as little as possible and kept in a healthy condition.

A commercial pregnancy test modified for field studies of fetal loss.

We describe simple modifications to the ICON II hCG (URINE) pregnancy test to provide a sensitive and specific urinary assay for hCG in field studies of fetal loss. The modified assay had a qualitative lower limit of detection of 0.30 IU/l, a 50% qualitative limit of 0.61 IU/l, a 100% qualitative limit of 1.16 IU/l, and a quantitative limit of 0.80 IU/l. Coefficients of variation ranged from 9.9% to 21.1%. Parallelism was observed among serially diluted subject samples. We used the assay in an 11-month prospective study of fetal loss in rural Bangladesh in which urine samples were collected twice-weekly from 494 women; 330 pregnancies and 93 fetal losses were detected. The median time to a positive pregnancy diagnosis was day 26 from last menses. The modified assay provided qualitative detection of early pregnancy comparable to laboratory assays, and appears to be well suited for use in epidemiologic or rural-population fetal loss studies.

Randomised controlled trial of L-carnitine as a nutritional supplement in preterm infants.

AIMS: To evaluate the effect of L-carnitine supplementation (25 mg/kg/d) on the growth and incidence of hypoglycaemia in preterm infants. METHODS: A double blind, placebo controlled randomised trial, stratified for gestational age, was conducted of 86 preterm infants between 28 and 34 gestational weeks. The median gestational ages in the carnitine group and placebo groups were 30.7 weeks (range 28.0 to 33.6) and 31.4 weeks (range 28.0 to 33.9), respectively. The median birthweights were 1.557 kg (range 0.944 to 2.275) and 1.645 kg (range 0.885 to 2.545), respectively. RESULTS: Mean plasma free carnitine concentrations were below values for normal term infants in both groups on day 1 (carnitine group 44.8 mumol/l, placebo group 25.5 mumol/l) in the placebo group on day 7 (50.7 mumol/l), but in neither group on days 14 and 28. Total, free, and acylcarnitine concentrations were significantly increased in both urine and blood in the L-carnitine group. There was no significant difference between the placebo and carnitine supplemented groups in growth rate, as assessed by weight, length, skinfold thickness and head circumference measurements, or in the incidence of episodes of hypoglycaemia. CONCLUSION: The addition of carnitine as a nutritional supplement at a dose of 25 mg/kg/day did not improve growth in our group of preterm infants nor protect them from episodes of hypoglycaemia.

Proprioception of the knee before and after anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to determine, first, if there is measurable deficit in proprioception in an anterior cruciate ligament (ACL)-deficient knee, either compared to the contralateral knee or external controls; second, if this deficit, if present, improves after ACL reconstruction; and third, if improvement occurs, what the time course of improvement is. TYPE OF STUDY: Prospective cohort study. METHODS: Patients undergoing ACL reconstruction at the University of Chicago, demonstrating a full and painless range of motion and no other knee ligament injury or history of previous knee surgery, were eligible. Twenty-six patients, with an average age of 25 years (range, 16 to 48) were enrolled. Average time from injury to reconstruction was 8 weeks. The patients' contralateral knee served as an internal control, and 26 age-matched and gender-matched healthy volunteers were enrolled as an external control group. ACL reconstructions were performed using a single-incision technique with either bone-patellar tendon-bone or quadrupled hamstring autograft. They were allowed immediate weightbearing as tolerated and participated in a standardized rehabilitation program, with the goal of returning to sport at approximately 6 months. Proprioception testing was carried out using an electrogoniometer, in a seated position. Joint position sense (JPS) and threshold to detection of passive motion (TDPM) were measured preoperatively and at 3 and 6 weeks and 3 and 6 months postoperatively. RESULTS: Mean KT-2000 values 6 months postoperatively were 1.38 mm (+/-2). Modified Lysholm score improved significantly (P <.01). Calculated r values were 0.65 for JPS and 0.96 for TDPM. No significant differences in postoperative proprioception were found between hamstring and patellar tendon grafts or among patients with meniscus injury, meniscus repair, or chondral injury. Preoperatively, the mean TDPM in both the injured and contralateral knees was significantly higher (worse) than in the external control knees (P =.008; P =.016). Evaluation of changes in proprioception from preoperative to 6 months postoperative showed significant improvement in both injured and contralateral knees (P =.04; P =.01). At 6-month follow-up, there was no significant difference from controls. CONCLUSIONS: TDPM was a more reliable method than JPS for testing proprioception before and after ACL reconstruction in this study. Bilateral deficits in knee joint proprioception (TDPM) were documented after unilateral ACL injury. Reconstruction of a mechanical restraint (ACL graft) was believed to have a significantly positive impact on early and progressive improvement in proprioception.

Hourly administration of GnRH to prepubertal gilts: endocrine and ovulatory responses from 70 to 190 days of age.

This study investigated the responsiveness of the pituitary-ovarian axis of prepubertal gilts to hourly injections (i.v.) with GnRH. Six gilts each at 70, 100, 150, and 190 d of age were assigned either to treatment with GnRH or saline. Treatments were given until gilts showed estrus or for 7 d, whichever came first. Hourly pulsing with GnRH resulted in gradually increasing concentrations of estradiol-17 beta (E2), a preovulatory surge of LH, and subsequently increased progesterone (P4) concentrations. The increase in serum P4 was preceded by ovulation and corpora lutea (CL) formation in two gilts 70 d of age and all older gilts. The interval (h) from start of GnRH treatment to peak E2 (88 +/- 3), peak LH (103 +/- 3), and concentrations of P4 greater than or equal to 1 ng/mL (144 +/- 4) did not differ (P greater than .50) for 18 gilts between 100 and 190 d of age. In two ovulating, 70-d-old gilts, the interval from onset of GnRH treatment to peak E2 (171 +/- 6), peak LH (186 +/- 0), and P4 greater than or equal to 1 ng/mL (216 +/- 4) was lengthened (P less than .001). Peak concentrations of E2 (pg/mL) were higher (P less than .01) at 190 d (48 +/- 2) and 150 d (49 +/- 2) than at younger ages and lower (P less than .01) in gilts 70 d of age (31 +/- 1) than in gilts 100 d of age (41 +/- 2). Peak LH (nanograms/milliliter) was higher (P less than .01) in gilts 100 d of age (12.7 +/- 6) than in older gilts. Concentrations of P4 were similar (P greater than .20) for all ovulating gilts. The number of CL (12.7 +/- .7) did not differ (P greater than .20) for 18 gilts 100 d of age or older but was higher (P less than .01) than that (4.5 +/- 1.1) for two gilts 70 d of age. Corresponding endocrine responses or ovulations were not observed in four 70-d-old gilts treated with GnRH or in gilts given saline. These findings indicate that the functional integration of the pituitary-ovarian axis is completed between 70 and 100 d of age. Hourly treatment with GnRH is an adequate stimulus to induce ovulation in prepubertal gilts as early as 70 d of age. Also, the number of follicles reaching ovulatory competency was similar (P greater than .20) in gilts between 100 and 190 d of age, when GnRH was given on a BW basis.

Prostaglandin-induced abortion in swine: endocrine changes and influence on subsequent reproductive activity.

Gilts were treated during midgestation with prostaglandin (PG) F to study the efficacy of different treatment regimens on induction of abortion and to determine the adverse consequences of PGF-induced abortion in swine. In study 1, pregnant purebred Duroc gilts (60 to 90 days of gestation) were given (IM) 500 micrograms of cloprostenol (n = 12), 20 mg of dinoprost tromethamine (n = 11), or 10 mg of dinoprost tromethamine repeated 12 hours later by an additional 10 mg of dinoprost tromethamine (n = 11). The percentage of gilts that aborted and percentage of aborted gilts that returned to estrus for each treatment group were as follows: cloprostenol, 91.7% and 100%, respectively; 20 mg of dinoprost tromethamine, 36.4% and 25.0%, respectively; and 10 + 10 mg of dinoprost tromethamine, 100% and 90.9%, respectively. Treatment with cloprostenol and with 10 + 10 mg of dinoprost tromethamine caused more gilts to abort (P less than 0.01) than did treatment with 20 mg of dinoprost tromethamine. Gilts that did not abort were given a second treatment with 10 + 10 mg of dinoprost tromethamine. When the abortions by gilts initially treated with 500 micrograms of cloprostenol or 10 + 10 mg of dinoprost tromethamine were combined with those re-treated with 10 + 10 mg of dinoprost tromethamine, 32 of 33 (97.0%) gilts aborted, and 30 of the 32 (93.8%) aborted gilts returned to estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Pseudoaneurysm of the lateral malleolar artery after an ankle sprain: case report and review of the literature.

A pseudoaneurysm of the peroneal artery or one of its branches is rare after trauma. The diagnosis is frequently delayed, resulting in substantial morbidity to the patient. The infrequent occurrence of this condition has resulted in a lack of diagnostic and treatment guidelines. However, when recognized, prompt attention involving either surgical ligation or embolization of the injured arterial branch is the most reliable method of treatment. Presented is a report of a patient who developed a lateral malleolar arterial pseudoaneurysm after an ankle sprain, which was treated successfully with aneurysmal excision and surgical ligation of the injured arterial branch. A review of the literature and treatment recommendations follow.

Personnel protection challenges in defense and waste management programs.

Three areas are targeted as offering major challenges to the health physicists of the future. One area is in the influx of new technologies, such as laser isotope separation (LIS) and its resultant impact on dosimetry. The LIS process, while generally reducing exposures, also has side effects that make it difficult to detect internal Pu contamination with present methods. Specifically, the LIS process will remove the 241Pu and its 241Am decay product, which is the estimator for Pu, from the 239Pu stream. A second area involves the requirements now being developed for waste management, which also challenges health physicists by insisting upon safe environments for workers who handle waste products while mandating confirmation and cleanup of hazardous wastes. Thus, developing remote inspection techniques will be vital for personnel protection. Finally, military health physicists are faced with the challenges posed to the civilian professionals as well as challenges unique to the military, such as the education of future health physicists to meet the complex military needs.

Absorbable implants in fracture management.

The use of absorbable implants has been studied extensively in the clinic and the laboratory. The limitations of absorbable implants are now well-known and include a finite life span and strength profile, the possible development of an inflammatory response, and their limitation to use in fractures that do not require traditional compression techniques. Advantages of these implants include the lack of necessity for removal at a later date, which has cost savings potential, their ease of use, and their strength, which may be sufficient for healing in certain situations. The most likely scenarios for the use of these implants in fracture management of the foot and ankle include syndesmotic disruptions, dislocations about the midfoot, and fractures of the medial malleolus.