325 research outputs found
Dynamic axial control over optically levitating particles in air with an electrically-tunable variable-focus lens
Efficient delivery of viruses, proteins and biological macromelecules into a micrometer-sized focal spot of an XFEL beam for coherent diffraction imaging inspired new development in touch-free particle injection methods in gaseous and vacuum environments. This paper lays out our ongoing effort in constructing an all-optical particle delivery approach that uses piconewton photophoretic and femtonewton light-pressure forces to control particle delivery into the XFEL beam. We combine a spatial light modulator (SLM) and an electrically tunable lens (ETL) to construct a variable-divergence vortex beam providing dynamic and stable positioning of levitated micrometer-size particles, under normal atmospheric pressure. A sensorless wavefront correction approach is used to reduce optical aberrations to generate a high quality vortex beam for particle manipulation. As a proof of concept, stable manipulation of optically-controlled axial motion of trapped particles is demonstrated with a response time of 100ms. In addition, modulation of trapping intensity provides a measure of the mass of a single, isolated particle. The driving signal of this oscillatory motion can potentially be phase-locked to an external timing signal enabling synchronization of particle delivery into the x-ray focus with XFEL pulse train.This work has been supported by the Australian Research Council under DP110100975. W. M. Lee acknowledges the
support of Australian Research Council Early Career Researcher Award, DE160100843
Quasinormal Spectrum and Quantization of Charged Black Holes
Black-hole quasinormal modes have been the subject of much recent attention,
with the hope that these oscillation frequencies may shed some light on the
elusive theory of quantum gravity. We study {\it analytically} the asymptotic
quasinormal spectrum of a {\it charged} scalar field in the (charged)
Reissner-Nordstr\"om spacetime. We find an analytic expression for these
black-hole resonances in terms of the black-hole physical parameters: its
Bekenstein-Hawking temperature , and its electric potential . We
discuss the applicability of the results in the context of black-hole
quantization. In particular, we show that according to Bohr's correspondence
principle, the asymptotic resonance corresponds to a fundamental area unit
.Comment: 4 page
Visualising Electronic Data Interchanging (EDI) and Virtual Information System (VIS) for Manipal Institutions
Paper discuses a case study on a virtual information system for a
group of institutions in Manipal. A demonstration model, which
has been developed, is discussed
Perturbative calculation of quasi-normal modes of Schwarzschild black holes
We discuss a systematic method of analytically calculating the asymptotic
form of quasi-normal frequencies of a four-dimensional Schwarzschild black hole
by expanding around the zeroth-order approximation to the wave equation
proposed by Motl and Neitzke. We obtain an explicit expression for the
first-order correction and arbitrary spin. Our results are in agreement with
the results from WKB and numerical analyses in the case of gravitational waves.Comment: 11 pages; references added and a sign error corrected; to appear in
CQ
Parallax of Galactic Cepheids from Spatially Scanning the Wide Field Camera 3 on the Hubble Space Telescope: The Case of SS Canis Majoris
We present a high-precision measurement of the parallax for the 12-day
Cepheid SS Canis Majoris, obtained via spatial scanning with the Wide Field
Camera 3 (WFC3) on the Hubble Space Telescope (HST). Spatial scanning enables
astrometric measurements with a precision of 20-40 muas, an order of magnitude
better than pointed observations. SS CMa is the second Cepheid targeted for
parallax measurement with HST, and is the first of a sample of eighteen
long-period >~ 10 days) Cepheids selected in order to improve the calibration
of their period-luminosity relation and eventually permit a determination of
the Hubble constant H_0 to better than 2%. The parallax of SS CMa is found to
be 348 +/- 38 muas, corresponding to a distance of 2.9 +/- 0.3 kpc. We also
present a refinement of the static geometric distortion of WFC3 obtained using
spatial scanning observations of calibration fields, with a typical magnitude
<~0.01 pixels on scales of 100 pixels.Comment: Submitted to ApJ on December 30, 2015. Comments welcome. Replaced
original version to fix latex errors that prevented tables to sho
Study of clinical characteristics of women with polycystic ovarian syndrome
Background: Polycystic ovarian syndrome (PCOS) is one of the most common endocrinal disorders of the reproductive age group causing anovulation, infertility incidence being 8.7-17.8%. It is associated with obesity, insulin resistance, dyslipidaemia and metabolic syndrome. This study was aimed to study the different clinical characteristics of women diagnosed with PCOS, attending a tertiary care hospital outpatient department.Methods: This was a hospital-based cross-sectional observational study of 200 patients with PCOS meeting the revised Rotterdam criteria from January 2018-June 2019 excluding pregnant and women with other systemic disorders. A detailed history and examination done, data collected regarding menstrual complaints, features of hyperandrogenism, hirsutism, acne, oily skin and Acanthosis Nigricans (AN) was documented. All data were statistically analyzed and compared using the chi-square or fissures’ exact test. p-value <0.05 considered significant.Results: A total of 200 patients with PCOS were included in the study, of which 41% were obese, 18% lean. The mean age was 24.44±5.62 years. Menstrual complaints were present in 88% -oligomenorrhea (49%) being the most common. 59% had hirsutism,38% of severe grade. Acanthosis nigricans was present in 33% of the patients. Correlation between hirsutism and alopecia, waist to hip ratio (WHR); acanthosis and WHR were statistically significant.Conclusions: PCOS is an ill-defined symptom complex where ethnicity plays a vital role, hence creating a greater need to know the characteristics of the syndrome in different populations and ethnicity. All women presenting with oligomenorrhea or other menstrual complaint should be investigated for PCOS and treated accordingly. The syndrome usually occurs with multiple characters. Though obesity is common in PCOS, non-obese are also at risk. The prevalence of AN and Hirsutism in PCOS were comparable. This mandates a need to increase awareness regarding the syndrome in the general population
Successful maternal and fetal outcome in patients with Takayasu arteritis: two case reports of Type I and Type IV in stage 2
Takayasu's arteritis, is a rare, chronic, idiopathic, inflammatory disease of the large arteries, primarily involves the aorta, its main branches as well as the coronary and pulmonary arteries. It is mostly seen among women with child bearing age group (80%). During pregnancy, the increased intravascular volume impair circulation and exacerbate aortic regurgitation, hypertension, and congestive heart failure. Hypertension is one of the serious complication that can develop, leading to intrauterine growth restriction, maternal heart failure, and fetal haemorrhage and during postpartum period
Epithelioid leiomyosarcoma: a rare uterine cancer
A uterine epithelioid leiomyosarcoma is a rare malignant tumour that arises from the smooth muscle lining the walls of the uterus. The exact cause of leiomyosarcoma, including uterine leiomyosarcoma accounting for 5 to 10% is unknown. Leiomyosarcoma is the most common subtype of uterine sarcoma, accounts for 1-2% of uterine malignancies. Malignancy should be suspected in menopausal women with tumour growth who are not on hormonal replacement therapy. A 64-year-old female had attained menopause 16 year back and developed postmenopausal bleeding since 2 months, with palpable mass, of 16 weeks size. Ultrasonography showed whorled mass lesions, endometrium and myometrium could not be seen separately. Uterus with both ovaries removed. Intra-operative findings showed 16 weeks uterine mass with size 15×10.5×10cm and weight 1kg with intramural fibroid. Necrotic and haemorrhagic areas with degenerative changes seen on cut section suggestive of malignancy. Histopathology and immunohistochemistry reported epithelioid leiomyosarcoma
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