Multi-band Oversampled Noise Shaping Analog to Digital Conversion

Oversampled noise shaping analog to digital (A/D) converters, which are commonly known as delta-sigma (ΔΣ) converters, have the ability to convert relatively low bandwidth signals with very high resolution. Such converters achieve their high resolution by oversampling, as well as processing the signal and quantization noise with different transfer functions. The signal transfer function (STF) is typically a delay over the signal band while the noise transfer function (NTF) is designed to attenuate quantization noise in the signal band. A side effect of the NTF is an amplification of the noise outside the signal band. Thus, a digital filter subsequently attenuates the out-of-band quantization noise. The focus of this thesis is the investigation of ΔΣ architectures that increase the bandwidth where high resolution conversion can be achieved. It uses parallel architectures exploiting frequency or time slicing to meet this objective. Frequency slicing involves quantizing different portions of the signal frequency spectrum using several quantizers in parallel and then combining the results of the quantizers to form an overall result. Time slicing involves quantizing various groups of time domain signal samples with different quantizers in parallel and then combining the results of the quantizers to form an overall output. Several interesting observations can be made from this general perspective of frequency and time slicing. Although the representation of a signal are completely equivalent in time or frequency, the thesis shows that this is not the case for known frequency and time sliced A/D architectures. The performance of such systems under ideal conditions are compared for PCM as well as for ΔΣ A/D converters. A multi-band frequency sliced architecture for delta-sigma conversion is proposed and its performance is included in the above comparison. The architecture uses modulators which realize different NTFs for different portions of the signal band. Each band is converted in parallel. A bank of FIR filters attenuates the out of-band noise for each band and achieves perfect reconstruction of the signal component. A design procedure is provided for the design of the filter bank with reduced computational complexity. The use of complex NTFs in the multi-band ΔΣ architecture is also proposed. The peformance of real and complex NTFs is compared. Performance evaluations are made for ideal systems as well as systems suffering from circuit implementation imperfections such as finite opamp gain and mismatched capacitor ratios

Epidermal Growth Factor Receptor (EGFR) as a Prognostic Marker: an Immunohistochemical Study on 315 Consecutive Breast Carcinoma Patients

Objective: To assess the independent and interdependent prognostic value of epidermal growth factor receptor (EGFR) in carcinoma of breast in female population. The Type I family of growth factor receptors includes epidermal growth factor receptor (EGFR also known as EGFRI). Methods: The expression of EGFR protein was analysed immunohistochemically on 315 tumour specimens of infiltrating ductal carcinoma of breast. These patients also had axillary lymph nodes sampling. Results: Overexpression and/or amplification of EGFR was observed in 70 (22.00%) tumours. Eleven (16%) were grade I, 43 (61%) grade II and 16 (23%) grade Ill tumours. Axillary lymph node metastasis had significant correlation with intensified positivity of EGFR (p\u3c 0.05). Significant number of EGFR positive patients developed local recurrence and distant metastases to brain, liver and bone (p\u3c 0.05). EGFR positivity showed significant correlation with the disease free and overall survival (p\u3c 0.05). At a median follow-up of48 (4 years) months in EGFR positive patients, the overall survival was 3.39 years and disease free survival was 2.86 years. EGFR negative tumour patients showed a better survival. In this group the overall survival was 4.62 years and the disease free survival was 4 years. Conclusion: EGFR analysis can be a useful indicator for the selection of patients who are at the high risk, for hormonal therapy decisions and can be useful as a target for new treatment modalities

Immunohistochemical Estrogen receptor determination in human Breast carcinoma: correlation with histologic differentiation and age of the patients

An immunohistochemical assay for the measurement of estrogen receptor (ER) has been evaluated on 290 consecutive human breast biopsy and mastectomy specimens in the year 1992 at The Aga Khan University Hospital laboratories. Immunohistochemical localization of estrogen receptor on frozen/paraffin section was scored in a semi-quantitative fashion incorporating both the intensity and the distribution of specific staining. Histologic grading of the tumour was performed according to Bloom’s method. In this study, 21% of the tumours were estrogen receptor negative, 15% were weak positive, 25% intermediate positive and 39% strong positive. Fifty percent of the well differentiated tumours showed strong ER positivity against 27% of the poorly differentiated tumours. Seventy eight percent of all negative estrogen receptors were in patients younger than 50 years of age (pre-menopausal group), while 52% of strong estrogen receptor positivity was observed in patients older than 50 years (post- menopausal). This study demonstrates the value of immunohistochemical method to determine the ER status in patients with advanced breast cancer

Phalaris minor control, resistance development and strategies for integrated management of resistance to fenoxaprop-ethyl

Phalaris minor (Littleseed canary grass) is a very important and annual weed of winter cereal crops. It is a very competitive weed of wheat, oat and barley crops in Pakistan. Usually, three aryloxyphenoxypropionate herbicides, fenoxaprop-P-ethyl, diclofop-methyl and clodinafop-propargyl are used as chemical weed control against different grassy weeds like P. minor, Avena sativa and Cyperus rotundus L. This review describes fenoxaprop-ethyl, a selective chemical herbicide used to control P. minor in wheat crop. High production of wheat is associated with its continuous use. But this practice enhances the development of resistant biotypes of P. minor. Different management approaches like preference of mechanical weeding over chemical weed control, integration of competitive varietal selection, crop rotation and herbicide rotation can be long duration strategies of resistance management in P. minor. However, tillage method, planting time, method of herbicide application, optimum dose, higher seed rate, early sowing, bed planting, stale seed bed and zero tillage are short duration resistance management strategies. Use of water extracts of herbicidal potential (allelopathic) plants can be effective integrated management of herbicide resistant against P. minor in wheat and for eco-friendly and sustainable weed management.Key words: Control, fenoxaprop-ethyl, management, Phalaris minor, resistance, wheat

Breast Diseases: a histopathological analysis of 3279 Cases at a Tertiary Care Center in Pakistan

Objective: To know the frequency of breast diseases in Pakistani females. Methods: A retrospective analysis of 3279 breast specimens received over a period of 4 years (1 993-1996) at the department of pathology, the Aga Khan University Hospital. Results: Out of a total of 3279 breast specimens, common breast lesions included infiltrating duct carcinoma 37%, followed by fibro adenoma 16.95%, fibrocystic change13.96%, mastitis 6.83% and duct ectasia 5.33%. Majority of the cases of infiltrating duct carcinoma were encountered in the 5th and 6th decades of life. Tumour size was 2 or \u3e2 cms. in 93% of cases and 40% of them showed 3 or \u3e3 positive lymph nodes. Grade I tumours were 11.38%, grade 11 59.17% and grade Ill tumours 29.47%. Correlation of grade with lymph node metastases (3 or \u3e3+ve nodes) showed 15 cases (1.53%) of grade 1, 178 cases (18.25%) of grade II and 68(6.97%) cases of grade Ill tumours. Conclusion: This study shows that in Pakistani females, the most commonly encountered lesion in carcinoma of the breast followed by the benign lesions such as fibro adenoma, fibrocystic disease & others. Breast carcinoma occurs at a younger age group with predominance of high-grade lesions and with frequent lymph node metastasis

Risk factors associated with short-term complications in mandibular fractures: the MANTRA study—a Maxillofacial Trainee Research Collaborative (MTReC)

Abstract Introduction Complications following mandibular fractures occur in 9–23% of patients. Identifying those at risk is key to prevention. Previous studies highlighted smoking, age and time from injury to presentation as risk factors but rarely recorded other possible confounders. In this paper, we use a collaborative snapshot audit to document novel risk factors and confirm established risks for complications following the treatment of mandibular fractures. Methods The audit was carried out by 122 OMFS trainees across the UK and Ireland (49 centres) over 6 months, coordinated by the Maxillofacial Surgery Trainees Research Collaborative. Variables recorded included basic demography, medical and social history, injury mechanism and type, management and 30-day outcome. Results Nine hundred and forty-seven (947) patients with fractured mandibles were recorded. Surgical management was carried out in 76.3%. Complications at 30 days occurred 65 (9%) of those who were managed surgically. Risk factors for complications included male sex, increasing age, any medical history, increasing number of cigarettes smoked per week, increasing alcohol use per week, worse oral hygiene and increased time from injury to presentation. Discussion We have used a large prospective snapshot audit to confirm established risk factors and identify novel risk factors. We demonstrate that time from injury to presentation is confounded by other indicators of poor health behaviour. These results are important in designing trial protocols for management of mandibular fractures and in targeting health interventions to patients at highest risk of complications. </jats:sec

An Overview of Sigma-Delta Converters: How a 1-bit ADC achieves more than 16-bit resolution

This article briefly describes conventional A/D conversion, as well as its performance modeling. We then look at the technique of oversampling, which can be used to improve the resolution of classical A/D methods. We discuss how sigma-delta converters use the technique of noise shaping in addition to oversampling to allow high resolution conversion of relatively low bandwidth signals. Next, we examine the use of sigma-delta converters to convert narrowband bandpass signals with high resolution. Several parallel sigma-delta converters, which offer the potential of extending high resolution conversion to signals with higher bandwidths, are also described

Efectos fitotóxicos de Euphorbia dracunculoides, una mala hierba del sistema de cultivo garbanzo-garbanzo de secano

Phytotoxic effect occurs when plants release chemicals that inhibit neighoubouring plants. Phytotoxic effects of aqueous extracts of different parts of Euphorbia dracunculoides L.  (green spurge) at two concentrations, and its infested soil were investigated on germination and seedling growth of chickpea (Cicer arietinum L.). The fruit extract at 1:20 (w/v) concentration caused maximum reduction (12%) in  germination of chickpea seeds while leaf extract at 1:10 (w/v)concentration resulted in maximum mean germination time value and minimum germination index of chickpea seeds. All the traits of chickpea seedling growth including emergence were adversely affected by the aqueous extracts at bothconcentrations. Further, the inhibition of chickpea seedling growth was more pronounced with 1:10 (w/v) concentrationwhereas the lower concentration (1:20 w/v) showed stimulatory effect on shoot length, seedling vigor index and chlorophyll contents of chickpea seedlings. The leaf extract at 1:10 (w/v) concentration proved most harmful to seedling growth and chlorophyll contents (76% reduction) of chickpea. Soil beneath the E. dracunculoides plants significantly reduced emergence (23%), seedling vigor index (55%) and chlorophyll content (19%) of chickpea but a significant increase in N (6%), P (16%) and K (4%) contents of chickpea seedlings was recorded. Thus it can be concluded that E. dracunculoides contains compounds in its tissues which may cause phytotoxic effects on chickpea under field conditions.Se produce un efecto fitot&oacute;xico cuando las plantas liberan sustancias qu&iacute;micas que producen inhibiciones en las plantaspr&oacute;ximas. Utilizando extractos acuosos a dos diferentes concentraciones de distintas partes de Euphorbia dracunculoides L., as&iacute; como del suelo infestado, se&nbsp; investigaron sus efectos fitot&oacute;xicos sobre la germinaci&oacute;n y crecimiento de pl&aacute;ntulas de garbanzo (Cicer arietinum L.). Extractos del fruto 1:20 (p/v) provocaron la m&aacute;xima reducci&oacute;n (12%) en la germinaci&oacute;n de las semillas de garbanzo, mientras que extractos de hoja 1:10 dieron el m&aacute;ximo valor del tiempo medio de germinaci&oacute;n y el m&iacute;nimo en el &iacute;ndice de germinaci&oacute;n. Todos los caracteres de crecimiento de las pl&aacute;ntulas de garbanzo, incluyendo la emergencia, fueron perjudicados por los extractos acuosos a ambas concentraciones. Adem&aacute;s, la concentraci&oacute;n 1:10 inhibi&oacute; el crecimiento de las pl&aacute;ntulas de garbanzo de forma m&aacute;s pronunciada, mientras que la 1:20 mostr&oacute; un efecto estimulante sobre la longitud de brotes y el &iacute;ndice de vigor y contenido de clorofila de las pl&aacute;ntulas de garbanzo. El&nbsp; extracto de hoja 1:10 result&oacute; m&aacute;s perjudicial para el crecimiento de pl&aacute;ntulas y el contenido de clorofila (76% de reducci&oacute;n). Suelo extra&iacute;do debajo de las plantas de E. dracunculoides redujo significativamente la emergencia&nbsp;(23%), el &iacute;ndice de vigor (55%) y el contenido de clorofila (19%) de las pl&aacute;ntulas, pero en cambio se registr&oacute; un aumento significativo en el contenido en N (6%), P (16%) y K (4%) de las pl&aacute;ntulas. Se concluye que E. dracunculoides contiene compuestos en los tejidos que pueden causar efectos fitot&oacute;xicos en garbanzo en condiciones de campo

A case of intramural pregnancy: the importance of differentiation from fibroid uterus

Breast cancer is an increasingly important cause of illness and death among women. In recent years several novel prognostic determinants of breast cancer have been identified which includes p53. Alterations of p53 are one of the most common abnormalities detected in primary breast cancer. In this study alteration of p53 in primary carcinoma breast was correlated with other pathological variables and disease outcome. In this prospective study the expression of p53 oncoprotein was analyzed immunohistochemically on 315 patient\u27s tumour specimens of infiltrating ductal carcinoma of breast from 1992 to 1997. These patients also had axillary lymph nodes sampling. Both univariate and multivariate statistical analysis was performed to analyze results including disease outcome. Overexpression of p53 was observed in 55.23% tumours. Axillary lymph node metastasis had significant correlation with positivity of p53 (

Relationship of p53 expression with clinicopathological variables and disease outcome: a prospective study on 315 consecutive breast carcinoma patients

Breast cancer is an increasingly important cause of illness and death among women. In recent years several novel prognostic determinants of breast cancer have been identified which includes p53. Alterations of p53 are one of the most common abnormalities detected in primary breast cancer. In this study alteration of p53 in primary carcinoma breast was correlated with other pathological variables and disease outcome. In this prospective study the expression of p53 oncoprotein was analyzed immunohistochemically on 315 patient\u27s tumour specimens of infiltrating ductal carcinoma of breast from 1992 to 1997. These patients also had axillary lymph nodes sampling. Both univariate and multivariate statistical analysis was performed to analyze results including disease outcome. Overexpression of p53 was observed in 55.23% tumours. Axillary lymph node metastasis had significant correlation with positivity of p53 (p\u3c0.05). A significant number of p53 patients developed local recurrence and distant metastases to brain, liver, lung and bone (p\u3c 0.05). At a median follow-up of 48 months (4 years) in p53 positive patients, the median overall survival (OS) was 3.0 years and disease free survival (DFS) was 2.5 years. p53 negative tumour patients showed a better survival. In this group the median OS was 3.8 years and the DFS was 3.3 years. The above findings have reinforced the view that p53 immunohistochemical detection is of help in detecting a subgroup of breast carcinoma patients who are at high risk. This may also be of particular relevance in decisions regarding adjuvant chemotherapy to these patients