Photonic correlation based on four wave mixing

Modern high-performance signal processing applications face constantly increasing processing speeds. The use of photonics potentially offers a much higher bandwidth and faster processing than what can be achieved in the electronic domain. This thesis investigates novel photonic techniques based on optical mixing for performing a correlation, a common signal processing task. The first photonic correlation scheme investigated uses four wave mixing (FWM) in a length of highly nonlinear fibre (HNLF) to mix template or reference wavelengths with a pump wavelength, which has been modulated by an input bit stream in order to produce copies of the input signal at the output idler wavelengths. The idler wavelengths are differentially delayed and summed at a photoreceiver to produce a correlation of the input bit stream and the reference bit pattern. This technique was investigated experimentally and results show that a correlation function is successfully achieved. A significant advantage of this technique compared to previous photonic correlation techniques is that modulation of the pump wavelength allows the “transmitter” to be remotely located, away from the correlation signal processing equipment. An extension of this technique successfully demonstrated the use of software control of the reference bit pattern using a multi-port photonic signal processor (Waveshaper). This enabled a more versatile form of correlator. True correlation requires the summation of negative signals. This is difficult for optical signals. A novel photonic technique based on FWM, which allows negative accumulation, was proposed for the first time. In this technique, a number of carrier and pump wavelengths are carefully selected such that individual mixing products occur at the same idler wavelength. Subtraction of optical fields at this wavelength can be achieved by changing the relative phase of pump wavelengths by 90 using a Waveshaper optical processor. This novel concept was verified via a simulation using ‘VPItransmissionMaker 9.0’ software. The simulation demonstrated that negative accumulation of optical signals could be achieved for the first time. In summary, novel photonic correlation techniques based on nonlinear optical mixing in optical fibre have been demonstrated and subtraction of optical fields using FWM has been demonstrated for the first time

Investigation of In vitro Release Kinetics of Carbamazepine from Eudragit® RS PO and RL PO Matrix Tablets

Purpose: The objective of this research work was to prepare and evaluate the effect of Eudragit RS PO and Eudragit RL PO polymers on the physical property and release characteristics of carbamazepine matrix tablets.Methods: Matrix tablets containing carbamazepine were prepared with Eudragit® RS PO alone as the rate-retarding polymer (coded batch series ‘A’) and also with a combination of Eudragit® RS PO and RL PO (coded batch series ‘B’). The tablets were characterized for hardness as well as for carbamazepine release. The release data were subjected to differentmodels in order to evaluate their release kinetics and mechanisms.Results: The hardness of batch series ‘A’ matrix tablet was >160 kg/cm2 while for batch series ‘B’, it was >170 kg/cm2. Carbamazepine tablets containing only Eudragit RS PO showed very slow release (less than 6% in 8 h) but when Eudragit RL PO was blended with Eudragit RS PO, the release rate improved significantly to 44% in 24 h (p < 0.05). Drug release mechanism was a complex mixture of diffusion and erosion.Conclusion: Carbamazepine matrix tablets of satisfactory hardness were produced. Furthermore, by blending Eudragit RS PO with Eudragit RL PO in the matrix, tablets of varying release characteristics can be prepared

Global Ultrasound Elastography Using Convolutional Neural Network

Displacement estimation is very important in ultrasound elastography and failing to estimate displacement correctly results in failure in generating strain images. As conventional ultrasound elastography techniques suffer from decorrelation noise, they are prone to fail in estimating displacement between echo signals obtained during tissue distortions. This study proposes a novel elastography technique which addresses the decorrelation in estimating displacement field. We call our method GLUENet (GLobal Ultrasound Elastography Network) which uses deep Convolutional Neural Network (CNN) to get a coarse time-delay estimation between two ultrasound images. This displacement is later used for formulating a nonlinear cost function which incorporates similarity of RF data intensity and prior information of estimated displacement. By optimizing this cost function, we calculate the finer displacement by exploiting all the information of all the samples of RF data simultaneously. The Contrast to Noise Ratio (CNR) and Signal to Noise Ratio (SNR) of the strain images from our technique is very much close to that of strain images from GLUE. While most elastography algorithms are sensitive to parameter tuning, our robust algorithm is substantially less sensitive to parameter tuning.Comment: 4 pages, 4 figures; added acknowledgment section, submission type late

Pattern of dyslipidemia in hypothyroid patients: A cross sectional study

Background: An association between thyroid dysfunction and dyslipidemia prevails. Levels of total cholesterol, low density lipoprotein cholesterol, triglycerides tend to increase as thyroid function declines.Objective: To find out the pattern of dyslipidemia in hypothyroid patients. Methods: Sixty cases were selected as a sample of convenience in this cross sectional study from in-patienl depa1tment of Medicine and Endocrinology, BSMMU. Meticulous history taking and thorough clinical examinations were done. Report of lipid profile and thyroid function tests were recorded from patients file. All the information's were recorded in a pre-designed sttuctured questionnaire. Collected data were classi­fied, edited, coded and entered into the computer for statistical analysis by using SPSS. Results: Among the 60 cases, 43 (72%) were female; 17(28%) were male. Age range was 24-59 years with a mean age of 38.80 (± I 0.35) years. Majority 38(65%) were housewife, followed by service holder 11(18.33%), 08(13.3%) were business men and 02(3.3%) had other occupations. Majority 42(70%) patients were taking thyroxin. Mean Total cholesterol (TC), LDL cholesterol, Triglycer­ide (TG) and HDL were 222.20(±42.25); 138.63(±31.51); 243.36(±83.13) and 37.30(±5.12) respectably. Conclusion: All hypothyroid subjects had dyslipidemia. The present study indicated that hypothyroidism was associated with an abnormal lipid profile, especially with respect to the levels of total cholesterol and triglyceride

Maternal outcomes in subsequent delivery after previous obstetric anal sphincter injury (OASI): a multi-centre retrospective cohort study.

INTRODUCTION AND HYPOTHESIS: Women with a history of obstetric anal sphincter injury (OASI) are at increased risk of recurrence (rOASI) at subsequent delivery; however, evidence regarding the factors influencing this risk is limited. Furthermore, little is known about what factors influence the decision to alternatively deliver by elective caesarean section (ELLSCS). METHODS: Retrospective univariate and multivariate logistic regression analysis of prospectively collected data from four NHS electronic maternity databases including primiparous women sustaining OASIS during a singleton, term, cephalic, vaginal delivery between 2004 and 2015, who had a subsequent delivery. RESULTS: Two thousand two hundred seventy-two women met the criteria; 10.2% delivering vaginally had a repeat OASI and 59.4% had a second-degree tear. Women having an ELLSCS were more likely to be Caucasian, older, have previously had an operative vaginal delivery (OVD) and have a more severe degree of OASI. Positive predictors for rOASI were increased birth weight and maternal age at both index and subsequent deliveries, a more severe degree of initial OASI and Asian ethnicity. The overall mediolateral episiotomy (MLE) rate was 15.6%; 77.2% of those who had an episiotomy sustained no spontaneous perineal trauma. Only 4.4% of women with a rOASI had an MLE, whilst the MLE rate was 16.9% in those without a recurrence (p  4 kg increased the risk 2.5 fold. CONCLUSIONS: Women with previous OASIS are at an increased risk of recurrence. A more liberal use of MLE during subsequent vaginal delivery could significantly reduce the risk of recurrence

Pattern of dyslipidemia in hypothyroid patients: A cross sectional study

Background: An association between thyroid dysfunction and dyslipidemia prevails. Levels of total cholesterol, low density lipoprotein cholesterol, triglycerides tend to increase as thyroid function declines. Objective: To find out the pattern of dyslipidemia in hypothyroid patients. Methods: Sixty cases were selected as a sample of convenience in this cross sectional study from in-patienl depa1tment of Medicine and Endocrinology, BSMMU. Meticulous history taking and thorough clinical examinations were done. Report of lipid profile and thyroid function tests were recorded from patients file. All the information's were recorded in a pre-designed sttuctured questionnaire. Collected data were classi­fied, edited, coded and entered into the computer for statistical analysis by using SPSS. Results: Among the 60 cases, 43 (72%) were female; 17(28%) were male. Age range was 24-59 years with a mean age of 38.80 (± I 0.35) years. Majority 38(65%) were housewife, followed by service holder 11(18.33%), 08(13.3%) were business men and 02(3.3%) had other occupations. Majority 42(70%) patients were taking thyroxin. Mean Total cholesterol (TC), LDL cholesterol, Triglycer­ide (TG) and HDL were 222.20(±42.25); 138.63(±31.51); 243.36(±83.13) and 37.30(±5.12) respectably. Conclusion: All hypothyroid subjects had dyslipidemia. The present study indicated that hypothyroidism was associated with an abnormal lipid profile, especially with respect to the levels of total cholesterol and triglyceride

Breadwinners and Homemakers: Migration and Changing Conjugal Expectations in Rural Bangladesh

The literature on marriage norms and aspirations across societies largely sees the institution as static – a tool for the assertion of masculinities and subordination of women. The changing meanings of marriage and conjugality in the contemporary context of globalisation have received scant attention. Based on research in rural Bangladesh, this article questions the usefulness of notions of autonomy and dependence in understanding conjugal relations and expectations in a context of widespread migration for extended periods, especially to overseas destinations, where mutuality is crucial for social reproduction, though in clearly genderdemarcated domains

Delineating ethnic and religious identities in research with British South Asians

The present essay presents a rationale for delineating ethnic and religious identities in empirical research into self-identification among British South Asians. It is argued that the delineation of these identities is important in order to (i) predict and explain the identificatory possibilities available to these individuals; (ii) explore the differential values attributed to these identities; (iii) the level of psychological 'connectedness' between the identities; and (iv) the inter-relations between these identities, particularly in relation to psychological coherence. It is argued that a systematic delineation of these identities may have favourable theoretical, empirical and practical outcomes

Disaster experiences, associated problems and lessons in southwestern coastal Bangladesh: exploring through participatory rural appraisal to enhance resilience

The southwestern coastal part of Bangladesh is highly vulnerable to different kinds of disasters due to the changing climatic conditions. With the lenses of rural communities here an approach to examine how were the different disasters experiences, what lesson they learnt and what are their present disaster associated problems and stakeholder’s networks they rely on to enhance their resilience. Qualitative data were collected through participatory rapid rural appraisal (100–150 persons), field observation, 12 focus group discussions (25–40 people/FGD), and key informant interviews (25 people) in four southwestern coastal districts and nine coastal villages of Bangladesh. Results showed that since long back to date drinking water crisis, poor roads, poverty, poor sanitation, and health problems are the main identified disaster-associated problems. After learning lessons from previous disaster experiences, the community people have improved and changed their practices mainly by storing emergency foods, house construction, and increasing disaster awareness. However, the coastal communities are combating with the problems that have both direct and indirect association with poor infrastructures. Therefore, the coastal communities urge and sketched for a better stakeholders’ supports and networks to minimize their problems and thus to enhance communities’ disaster resilience

Two cultures, one identity: formulations of Australian Isma'ili Muslim identity

The Shi'a Imami Nizari Isma'ili Muslims have often been considered the "poster child" for pluralistic integration (Cayo 2008). This ethos has been inculcated within members of the community, with its adherents seeing themselves as a diverse and multi-ethnic collective. Nevertheless, despite this purported pluralism, social research on the Isma'ilis has primarily focused on the diasporic and post-diasporic migrant communities of South Asian descent, the 'first and second-generation immigrants,' in the Euro-American context (Mukadam and Mawani 2006, 2009; Nanji 1983, 1986). The experiences of co-religionists in other contexts have often been neglected. This study examines how members of the self-described geographically and socially isolated Isma'ili community in Australia construct their identity vis-à-vis the larger, global, Isma'ili community, and how they have responded to the potential of identity threat given the arrival of another group of Isma’ilis with a differing migratory history integrating into the extant community. Using the approach of identity process theory, this study examines how salient features of identity are constructed amongst the Australian Isma'ilis, how religion and identity take on multiple meanings within the Australian Isma'ili context, and, finally, sheds light on the self-sufficiency of this community despite geographic and social isolation