Photonic ring resonator filters for astronomical OH suppression.

Ring resonators provide a means of filtering specific wavelengths from a waveguide, and optionally dropping the filtered wavelengths into a second waveguide. Both of these features are potentially useful for astronomical instruments. In this paper we focus on their use as notch filters to remove the signal from atmospheric OH emission lines from astronomical spectra. We derive the design requirements for ring resonators for OH suppression from theory and finite difference time domain simulations. We find that rings with small radii (< 10 µm) are required to provide an adequate free spectral range, leading to high index contrast materials such as Si and Si3N4. Critically coupled rings with high self-coupling coefficients should provide the necessary Q factors, suppression depth, and throughput for efficient OH suppression, but will require post-inscription tuning of the coupling and the resonant wavelengths. The overall prospects for the use of ring resonators in astronomical instruments is promising, provided efficient fibre-chip coupling can be achieved.

Ferromagnetism in the Mott insulator Ba2NaOsO6.

Results are presented of single crystal structural, thermodynamic, and reflectivity measurements of the double-perovskite Ba2NaOsO6. These characterize the material as a 5d1 ferromagnetic Mott insulator with an ordered moment of approximately 0.2microB per formula unit and TC=6.8(3) K. The magnetic entropy associated with this phase transition is close to Rln2, indicating that the quartet ground state anticipated from consideration of the crystal structure is split, consistent with a scenario in which the ferromagnetism is associated with orbital ordering.

Embolic phenomena during computer-assisted and conventional total knee replacement.

Systemic emboli released during total knee replacement have been implicated as a cause of peri-operative morbidity and neurological dysfunction. We undertook a prospective, double-blind, randomised study to compare the cardiac embolic load sustained during computer-assisted and conventional, intramedullary-aligned, total knee replacement, as measured by transoesophageal echocardiography. There were 26 consecutive procedures performed by a single surgeon at a single hospital. The embolic load was scored using the modified Mayo grading system for echogenic emboli. Fourteen patients undergoing computer-assisted total knee replacement had a mean embolic score of 4.89 (3 to 7) and 12 undergoing conventional total knee replacement had a mean embolic score of 6.15 (4 to 8) on release of the tourniquet. Comparison of the groups using a two-tailed t-test confirmed a highly significant difference (p = 0.004). This study demonstrates that computer-assisted knee replacement results in the release of significantly fewer systemic emboli than the conventional procedure using intramedullary alignment.

Simulation of normal, carrier and affected controls for large-scale genotyping of cattle for factor XI deficiency.

An insertion mutation within exon 12 of the factor XI gene has been described in Holstein cattle. This has opened the prospect for large-scale screening of cattle using the polymerase chain reaction (PCR) technique for the rapid identification of heterozygous animals. To facilitate such a screening process, the mutant and normal alleles of factor XI gene, represented by 244- and 320-bp PCR amplified fragments, were individually cloned in Escherichia coli using a multicopy plasmid cloning vehicle to generate pFXI-N and pFXI-M, respectively. The authenticity of the inserts was confirmed by nucleotide sequencing. A nested PCR method was developed, by which PCR amplicons generated from primers with annealing sites on the recombinant plasmids and by flanking the insert were used as templates for amplification of the diagnostic products using factor XI gene-specific primers. An equimolar mixture of both PCR amplicons, originating from pFXI-N and pFXI-M, constituted the carrier control while the individual amplicons were the affected and normal controls. The controls were used as references for in-gel comparison to screen a population of 307 cattle and 259 water buffaloes; the frequency of the mutant allele was found to be 0. No DNA size standards were required in this study. The simulated control DNA samples representing normal, carrier and affected cattle have the potential to help in large-scale screening of a cattle population for individuals that are carriers or affected by factor XI deficiency.

Medical students' self-confidence in performing direct ophthalmoscopy in clinical training.

BACKGROUND: Although direct ophthalmoscopy is an important skill that medical students must practice to gain proficiency, limited time is generally available in medical school curricula. More targeted and effective teaching could result from a clearer understanding of medical students' self-reported needs and weaknesses in performing direct ophthalmoscopy. METHODS: A cross-sectional survey was conducted at a Canadian university to determine the confidence of medical students in their skill in performing direct ophthalmoscopy. The responses of 208 participants who volunteered to complete a 21-item questionnaire were analyzed. RESULTS: Although clerks were significantly more confident in their overall skill (chi2=28.03, p<0.001) than were first- and second-year students, 47% of clerks were "not at all" or only "a little" confident in performing direct ophthalmoscopy on an undilated pupil. Respondents who had practiced on more than 10 occasions outside of formal teaching were significantly more confident in their overall skill than those who had not (chi2=22.94, p<0.001). Overall, 87% (77% of clerks) were "quite" or "extremely" interested in more practice and training on direct ophthalmoscopy. INTERPRETATION: A large proportion of medical students reported not being confident in various aspects of their skill in performing direct ophthalmoscopy. Self-confidence was significantly greater among students who practiced outside of formal teaching sessions. Most students were interested in additional training, and medical schools should emphasize the importance of practicing whenever appropriate.

Simulation of normal, carrier and affected controls for large-scale genotyping of cattle for factor XI deficiency

An insertion mutation within exon 12 of the factor XI gene has been described in Holstein cattle. This has opened the prospect for large-scale screening of cattle using the polymerase chain reaction (PCR) technique for the rapid identification of heterozygous animals. To facilitate such a screening process, the mutant and normal alleles of factor XI gene, represented by 244- and 320-bp PCR amplified fragments, were individually cloned in Escherichia coli using a multicopy plasmid cloning vehicle to generate pFXI-N and pFXI-M, respectively. The authenticity of the inserts was confirmed by nucleotide sequencing. A nested PCR method was developed, by which PCR amplicons generated from primers with annealing sites on the recombinant plasmids and by flanking the insert were used as templates for amplification of the diagnostic products using factor XI gene-specific primers. An equimolar mixture of both PCR amplicons, originating from pFXI-N and pFXI-M, constituted the carrier control while the individual amplicons were the affected and normal controls. The controls were used as references for in-gel comparison to screen a population of 307 cattle and 259 water buffaloes; the frequency of the mutant allele was found to be 0. No DNA size standards were required in this study. The simulated control DNA samples representing normal, carrier and affected cattle have the potential to help in large-scale screening of a cattle population for individuals that are carriers or affected by factor XI deficiency.

Congenital melanocytic nevus studded with strawberry haemangioma on the scalp.

A six-month-old male infant presented with congenital melanocytic nevus (CMN) studded with strawberry haemangioma on the right side of scalp since birth. Both lesions were gradually increasing up to the present size. The case is being reported for its rare occurrence.

Pityriasis rosea unilateralis.

The classical pityriasis rosea presents with erythematous papulosquamous lesions. It has got many clinical and morphological variants. Pityriasis rosea unilateralis is very rare variant of pityriasis rosea. We are reporting two cases of unilateral pityriasis rosea.

Topical 20% KOH--an effective therapeutic modality for moluscum contagiosum in children.

Topically 20% KOH aqueous solution once daily at bedtime was applied in 27 children having molluscum contagiosum by their parents, till lesions showed signs of inflammation or superficial ulceration. 24 children (88.9%) completed the trial and complete clearance was achieved after a mean period of 17 days. No recurrence was observed during follow up period. Thus in this open trial topical 20% KOH aqueous solution has proved to be convenient, easy to apply at home, safe and inexpensive alternative therapeutic modality for the treatment of molluscum contagiosum in children.

Pachyonychia congenita-like nail changes treated successfully with a combination of vitamins A and E: a case report.

A 20-year-old man presented with thickening, subungual hyperkeratosis and discoloration of all the nails of both hands and both great toes since birth. No other ectodermal abnormalities were found. Treatment with vitamins A and E in high doses along with a moisturizing ointment topically for one year resulted in complete resolution of all nail abnormalities.

Bilateral herpes--Zoster of widely separated dermatomes in a non-immunocompromised female.

Herpes zoster involving simultaneously left maxillary dermatome and right 2nd lumbar dermatome in a non-immunocopromised 24-year-old female is being reported due to its rarity.

Skin grafting in chronic leg ulcers--a dermatologist's domain.

A case of chronic leg ulcer for the last two years in a 50-year-old male, not responding to conventional therapeutic modalities had shown faster healing and excellent cosmetic results by undertaking split skin thickness grafting in the hands of a dermatologist.

A study of behavioural changes and clinical evaluation of leprosy in school going children of leprosy parents.

Seventy-seven school going children in age group 5-15 years having one or both parents affected with leprosy and staying away from their parents in charitable ashram cum school for the last 6 months to 6 years time were examined for any behavioural changes and signs and symptoms of leprosy. None of these children showed any behavioural changes or signs and symptoms of leprosy.

Giant hairy 'bathing trunk' naevus with multiple congenital melanocytic naevi.

A 23-day-old male infant had hairy 'bathing trunk' naevus covering, neck and upper trunk along with multiple congenital melanocytic naevi scattered all over the body.

Traumatic phacocele.

We report a case of traumatic phacocele in a 42-year-old patient with a history of congenital glaucoma and bilateral goniotomies as an infant. Her left eye had little vision and poorly controlled intraocular pressure but was comfortable until her presentation after blunt trauma. Phacocele or subconjunctival dislocation of the crystalline lens is a rare consequence of blunt trauma, particularly in a patient whose only previous ocular surgery was goniotomy more than 40 years ago.

Estrogen modulates sexually dimorphic contextual fear conditioning and hippocampal long-term potentiation (LTP) in rats(1).

The present study examined the role of ovarian steroids in contextual fear conditioning and hippocampal synaptic plasticity in female rats. In experiment 1, adult female rats were ovariectomized and submitted to contextual fear conditioning, a procedure in which rats received unsignaled footshock in a novel observation chamber; freezing behavior served as the measure of conditional fear. Ovariectomized female rats froze at levels comparable to male rats, both of which froze significantly more than sham-operated female rats. In experiment 2, estrogen replacement in ovariectomized female rats reduced fear conditioning to a level comparable to that of sham-operated females in experiment 1. In experiment 3, the influence of estrogen on the induction of long-term potentiation (LTP) at perforant path-dentate granule cell synapses in ovariectomized female rats was examined. Estrogen decreased both population spike LTP and EPSP-spike potentiation at perforant path synapses. Taken together, these experiments indicate that ovarian steroids regulate both sexually dimorphic behavior and hippocampal plasticity in a fear-conditioning paradigm.

Chemical peeling--evaluation of glycolic acid in varying concentrations and time intervals.

Thirty-one patients with melasma, 4 with superficial post acne scarring and one each with xeroderma pigmentosum and epidermal naevus were studied to know the efficacy of glycolic acid for chemical peeling in varying concentrations and time intervals such as 35% (4 minutes), 52.5% (3 minutes), 70% (2 minutes) at varying intervals upto 6 months. These patients were in the age group of 17-44 years. These patients were followed up regularly. Results showed significant improvement when peeling was done with 52.5% glycolic acid for 3 minutes in melasma, 70% glycolic acid for 2 minutes in superficial post acne scarring.

Intraoral giant condyloma acuminatum.

A case of intraoral giant condyloma acuminatum is reported in a 50- year- old Indian. He did not respond to topical application of podophyllin 20% but responded partially to electric cauterisation. Surgical excision was done to get rid of the warty growth completely. Since there were no skin or genital lesions and no history of marital or extramarital sexual contact the lesion was probably acquired from environmental sources. Nonsexual transmission should be considered especially when the lesions are extragenital.