Cross-spectrum measurement of thermal-noise limited oscillators.

Cross-spectrum analysis is a commonly used technique for the detection of phase and amplitude noise of a signal in the presence of interfering uncorrelated noise. Recently, we demonstrated that the phase-inversion (anti-correlation) effect due to amplitude noise leakage can cause complete or partial collapse of the cross-spectral function. In this paper, we discuss the newly discovered effect of anti-correlated thermal noise that originates from the common-mode power divider (splitter), an essential component in a cross-spectrum noise measurement system. We studied this effect for different power splitters and discuss its influence on the measurement of thermal-noise limited oscillators. We provide theory, simulation and experimental results. In addition, we expand this study to reveal how the presence of ferrite-isolators and amplifiers at the output ports of the power splitters can affect the oscillator noise measurements. Finally, we discuss a possible solution to overcome this problem.

Serological diagnosis of dengue in laboratory practice in Kolkata.

PURPOSE: To find out the most suitable serological investigative procedures to diagnose dengue cases effectively in the laboratory practice identifying primary and secondary cases as well as period of suffering. MATERIALS AND METHODS: Dengue suspected cases sent to the laboratory in 2012 in central Kolkata by the local physicians were categorised into seven panels according to the investigations asked for such as (1) only dengue-specific NS1 antigen (2) only IgM antibodies, (3) NS1+IgM+IgG antibodies, (4) only IgM and IgG, (5) NS1+IgM, (6) NS1+IgG and (7) only IgG. RESULTS: Out of 1892 suspected cases, dengue was diagnosed in 725 (38.3%). Through panels I, II, III, IV, V, VI and VII, it was possible to diagnose dengue in (I) 35.98% (435/1209), (II) 37.5% (24/60), (III) 49% (173/354), (IV) 30.8% (68/221), (V) 60.5% (23/38), (VI) 40% (2/5) and (VII) 0 of cases respectively. Detail information such as confirmed diagnosis, duration of the disease (whether early or prolonged) and classification of primary and secondary dengue in such early or prolonged stages would only be possible in panel III, which information would be helpful for effective monitoring and treatment of dengue patients. In all other panels, merely fragmentary information would be obtained. CONCLUSIONS: Serodiagnostic tests dengue-specific NS1 antigen and IgM and IgG antibodies when conducted simultaneously would be able to diagnose confirmed dengue cases categorising primary and secondary dengue along with the duration of the disease, whether early or prolonged.

A collapse of the cross-spectral function in phase noise metrology.

Cross-spectral analysis is a mathematical tool for extracting the power spectral density of a correlated signal from two time series in the presence of uncorrelated interfering signals. We demonstrate and explain a set of amplitude and phase conditions where the detection of the desired signal using cross-spectral analysis fails partially or entirely in the presence of a second uncorrelated signal. Not understanding when and how this effect occurs can lead to dramatic under-reporting of the desired signal. Theoretical, simulated and experimental demonstrations of this effect as well as mitigating methods are presented.

Operation of an optically coherent frequency comb outside the metrology lab.

We demonstrate a self-referenced fiber frequency comb that can operate outside the well-controlled optical laboratory. The frequency comb has residual optical linewidths of < 1 Hz, sub-radian residual optical phase noise, and residual pulse-to-pulse timing jitter of 2.4 - 5 fs, when locked to an optical reference. This fully phase-locked frequency comb has been successfully operated in a moving vehicle with 0.5 g peak accelerations and on a shaker table with a sustained 0.5 g rms integrated acceleration, while retaining its optical coherence and 5-fs-level timing jitter. This frequency comb should enable metrological measurements outside the laboratory with the precision and accuracy that are the hallmarks of comb-based systems.

Constitutional, organopathic and combined homeopathic treatment of benign prostatic hypertrophy: a clinical trial.

BACKGROUND: Benign Prostatic Hypertrophy (BPH) is common in older men. This study compared homeopathic treatment strategies using constitutional medicines (CM) or organopathic medicines (OM) alone or in combination (BCOM) in patients suffering from BPH. METHODS: 220 men aged 30-90 years were recruited in Odisha, India. Patients presenting symptoms of prostatism, with or without evidence of bladder outflow obstruction were included in the study. Patients with serum prostate specific antigen (PSA)> 4 nmol/mL, malignancy, complete urine retention, stone formation and gross bilateral hydronephrosis were excluded. Patients were sequentially allocated to OM, CM or BCOM. The main outcome measure was the International Prostate Symptom Score (IPSS). RESULTS: 73, 70 and 77 patients respectively were sequentially allocated to OM, CM or BCOM. 180 patients (60 per group) completed treatment and were included in the final analysis. Overall 85% of patients showed improvement of subjective symptoms such as frequency, urgency, hesitancy, intermittent flow, unsatisfactory urination, feeble stream, diminution of residual urine volume but there was no reduction in prostate size. Treatment response was highest with BCOM (38.24%) compared to OM (31.62%) and CM (30.15%). Effect sizes were highest for the decrease in IPSS, residual urine volume and urinary flow rate.

Dengue serosurveillance in Kolkata, facing an epidemic in West Bengal, India.

BACKGROUND & OBJECTIVES: A dengue outbreak occurred throughout West Bengal, India starting from August 2005. The objectives of this study were: (i) documentation of suspected cases, confirmed by MAC ELISA; (ii) a longitudinal serosurveillance of dengue in Kolkata by detecting denguespecific IgG and IgM antibodies in suspected cases and to note the seasonal incidence; (iii) to get information about proportion of primary, secondary and old dengue cases and persons free from dengue in the population tested; and (iv) to get some idea to forecast advent of dengue and dengue epidemic/precipitation of DHF. METHODS: The epidemiological data were collected from different sources including Calcutta School of Tropical Medicine and Government of West Bengal. For serosurveillance in Kolkata, serum of each suspected patient was examined for detection of IgG and IgM antibodies using the microwell ELISA dengue fever kit. RESULTS: Altogether, 6293 ELISA IgM reactive cases were documented out of 12,059 persons (52.18%) tested in the whole of West Bengal, involving 18 districts with 34 deaths. Serosurveillance of 1668 persons from August 2005 to December 2007 in Kolkata showed that only 18.1% (302) suffered from dengue, 6.03% (101) from primary, 12.03% (201) from secondary dengue, 20.44% (341) were not sufferers of dengue and 61.45% (1025) were old dengue cases. Though stray dengue cases were found perennially, most of the cases occurred in the post-monsoon season, with a peak in September. Of dengue patients, 63.24% (191) were males. Secondary dengue cases outnumbered primary dengue cases. So, possibility of DHF would remain in all age groups and in those persons who suffered from dengue on earlier occasion. Dengue cases drastically reduced in two subsequent post-epidemic years (2006 and 2007). INTERPRETATION & CONCLUSION: Dengue serosurveillance studies may give some idea about advent, intensity, transmission season, seasonal incidence, waxing and warning, and impending epidemic of dengue and DHF. A large-scale active longitudinal serosurvey along with the study of vector capacity and vector competence would provide more correct information.

Death due to chikungunya.

After its first appearance in Kolkata (Calcutta) during 1963-1965, chikungunya occurred in epidemic form in India in 17 states and union territories. There were 13,90,322 cases suspected to be suffering from chikungunya in 2006, 59,535 in 2007 and 11,222 in 2008; in 2006, 2007 and 2008 there were 15,961, 7,837 and 262 samples, respectively, sent to the National Institute of Virology, Pune, and the National Institute of Communicable Disease, Delhi, for serological diagnosis. Of these, 2001, 1826 and 44, respectively, were confirmed as chikungunya. There were no deaths (data from the National Vector Borne Disease Control Programme, Government of India).

Chikungunya in west bengal, India.

Fever of unknown origin broke out in several districts of West Bengal, from August 2007 to December 2007. The cases were suffering from high fever, severe joint pain lasting for several weeks after clinical cure and appearance of skin rashes. Patients' sera were collected at least five days after fever and were analyzed to detect specific IgM antibodies. A total of 800 patients were investigated and 321 (40.13%) were found to be reactive for Chikungunya antibodies. Of the patients, 66% were male. Predominant signs and symptoms observed in the sero-positive cases were fever (100%), arthralgia (96%) and diffuse erythematous skin rash (94%). Of the patients, 3% had haemorrhagic manifestations. Re-emerging Chikungunya virus spread in epidemic form in several districts of West Bengal after a gap of four decades.

Studies on dengue and dengue haemorrhagic fever (DHF) in West Bengal State, India.

A large outbreak of dengue and dengue haemorrhagic fever (DHF) occurred from August to November 2005 involving all districts of West Bengal. Altogether 6293 persons were serologically diagnosed to be suffering from dengue through detection of IgM antibodies, with 27 (0.42%) seropositive deaths. In Kolkata alone 3967 persons were affected with 14 deaths. A total of 874 sera samples from febrile patients were quantitatively analysed for IgG and IgM antibodies using the IVD microwell ELISA dengue fever test kit. In 21.6%, no antibody was detected and 52.6% had only IgG antibodies. In 8.9% only IgM antibodies and in 16.8% both IgG, IgM antibodies were present, suggesting primary and secondary dengue respectively. About 10% of secondary dengue would develop DHF. As in this outbreak secondary dengue was 65.3% of total dengue cases, so of the 6293 dengue victims presumably, 3998 had secondary dengue, thus having risk of DHF in about 400 persons. Case fatality rate amongst DHF patients was 8.5%. This study also indicated that DHF would be a nagging problem in coming days. Age-group analysis of primary and secondary dengue cases revealed that although secondary cases occurred in all ages, more of primary cases belonged to younger ages (1-10) years and more of secondary cases in middle to older ages. Prevailing type during this outbreak was DEN3. This epidemiological study of an outbreak categorized prevalence of primary and secondary dengue, calculated risk factors for precipitation of DHF, model of which could be utilized to compare and evaluate future epidemiological pattern, where-ever and whenever applicable.

Estimating parasite density in patients suffering from falciparum malaria in an endemic area in Kolkata.

Parasite density of one hundred patients suffering from falciparum malaria in an endemic area in Kolkata was determined using three different methods. In the first of these, parasite density per microlitre of blood in a patient was determined using parasite count adjusted by average WBC count (i.e. 8000/microliter) observed in microscopic fields of the thick film. In the remaining two methods, only raw (i.e. unadjusted) parasite counts in microscopic fields of the same slide were used. A statistical analysis was carried out in detail to compare these methods based on raw and adjusted parasite counts and also to find out a suitable method which can be used in practice. Estimating the density of parasites is of primary importance in determining the severity of infection. Furthermore, parasite density can help in identifying short-treatment and long-treatment failure vis-a-vis detection of development of resistance in P. falciparum against the drug used. This article reports some findings that indicate the existence of a potentially dangerous situation in the study area.

Malariogenic situations amounting to premunition in areas of Ajodhya Hills of District Purulia, West Bengal.

Since a long time, Purulia District in West Bengal has been endemic for malaria. In 1997 and 1998, the district contributed 12.4% (9932 out of 79,811) and 10.0% (13,248 out of 130,288) of malaria cases respectively occurring in West Bengal, resulting 9.45% (7 out of 74) and 5.5% (4 out of 72) of deaths respectively in the state. ABER of the district was 10.4% in 1997 and 8.5% in 1998.

Emerging Plasmodium falciparum in an endemic area in Calcutta.

Calcutta is now intensely malarious. Malarial infections are detected in every month. In an endemic area in central Calcutta a year-long study from August 1996 to July 1997 reveals that 31.47% of all cases are due to Plasmodium falciparum infection. A competition is going on between P vivax and P falciparum to gain upperhand. An equilibrium is there in the month of January (1997), when P vivax and P falciparum cases constitute 51.13% and 49.43% respectively. The highest and lowest percentage of P falciparum infection is in December 1996 (67.98%) and in May 1997 (0.89%) which is just reverse in the case of P vivax in December 1996 (33.60%) and in May 1997 (99.10%). Three imported cases of P malariae have been detected but the patients cannot be traced. Six cases of mixed infections have been found.

Urban malaria vector biology.

One of the main reasons for the set-back in the urban malaria control programme is the peculiar biobehaviour of the principal urban malaria vector Anopheles stephensi. Certain relevant facts such as incrimination as the vector of malaria, sibling or biological species, resting habitat, manlanding behaviour, seasonal prevalence, blood meal analysis, longevity, parity status, daily survival and mortality rates of adults, breeding habitats and vertical distribution of larvae of An. stephensi have been discussed. Determination of density of the vector using various parameters and their relation to malaria endemicity in an urban situation have been reviewed. An. stephensi has become resistant to DDT, HCH, malathion and propoxur in many places in India. Hence for control source reduction, use of predators such as fish and biolarvicides such as Bacillus thuringiensis var israelensis H14 and B. sphaericus, personal protection, i.e., use of appropriate clothing, bed nets, indigenous repellents, etc., information, education and communication (IEC) are to be stressed.