Hardware-Amenable Structural Learning for Spike-based Pattern Classification using a Simple Model of Active Dendrites

This paper presents a spike-based model which employs neurons with functionally distinct dendritic compartments for classifying high dimensional binary patterns. The synaptic inputs arriving on each dendritic subunit are nonlinearly processed before being linearly integrated at the soma, giving the neuron a capacity to perform a large number of input-output mappings. The model utilizes sparse synaptic connectivity; where each synapse takes a binary value. The optimal connection pattern of a neuron is learned by using a simple hardware-friendly, margin enhancing learning algorithm inspired by the mechanism of structural plasticity in biological neurons. The learning algorithm groups correlated synaptic inputs on the same dendritic branch. Since the learning results in modified connection patterns, it can be incorporated into current event-based neuromorphic systems with little overhead. This work also presents a branch-specific spike-based version of this structural plasticity rule. The proposed model is evaluated on benchmark binary classification problems and its performance is compared against that achieved using Support Vector Machine (SVM) and Extreme Learning Machine (ELM) techniques. Our proposed method attains comparable performance while utilizing 10 to 50% less computational resources than the other reported techniques.Comment: Accepted for publication in Neural Computatio

Delay Learning Architectures for Memory and Classification

We present a neuromorphic spiking neural network, the DELTRON, that can remember and store patterns by changing the delays of every connection as opposed to modifying the weights. The advantage of this architecture over traditional weight based ones is simpler hardware implementation without multipliers or digital-analog converters (DACs) as well as being suited to time-based computing. The name is derived due to similarity in the learning rule with an earlier architecture called Tempotron. The DELTRON can remember more patterns than other delay-based networks by modifying a few delays to remember the most 'salient' or synchronous part of every spike pattern. We present simulations of memory capacity and classification ability of the DELTRON for different random spatio-temporal spike patterns. The memory capacity for noisy spike patterns and missing spikes are also shown. Finally, we present SPICE simulation results of the core circuits involved in a reconfigurable mixed signal implementation of this architecture.Comment: 27 pages, 20 figure

Sentinel lymph node scintigraphy and radioguided dissection in breast carcinoma: an initial experience at Aga Khan University Hospital

Objective: To evaluate the efficacy of SLN biopsy using imaging and gamma probe in breast cancer and to establish this technique at Aga Khan University Hospital.Methods: Thirty two patients (mean age 33-76 yrs) with operable breast carcinoma (4 with post-neo adjuvant therapy) with clinically negative axilla were studied. In 28 patients simultaneous axillary dissection was performed. Sentinel lymph nodes (SLN) scintigraphy was performed a day before surgery by injecting Tc-99m labeled nannocolloid sub-dermally in the peri-areolar region in 24 and peri-tumoral in remaining 8. First lymph node (LN) to appear to on the scan was labeled as SLN and marked on the skin. Blue dye was also injected in all patients and blue and hot LN was explored in the axilla using gamma probe.Results: The sentinel LN was identified in 31 patients (96.9% success rate) while in one patient (3.1%) SLN was not visualized on the scan (negative study) and this was a post-neo-adjuvant therapy case. The blue dye successfully localized the sentinel LNs in all 32 cases The gamma probe guided localization was successful in all 31 while in one case with post-neo-adjuvant chemotherapy it failed. In 9 out of 32 (28.1%) cases SLN was positive for metastasis and in 6 out of these 9 (66.6%) the SLN was the only metastatic node. This includes the post-neo-adjuvant case as well. There was no case of skip metastasis, i.e. negative SNL and positive other axillary nodes. In remaining 23 (71.9%) cases SLN was negative for metastasis and in all, axilla was free of disease (NPV of 100%).CONCLUSION: Lymphoscintigraphy with gamma probe guided SNL biopsy is safe, simple and highly reliable technique. With blue dye technique it reduces the blindness of the procedure if performed independently but increases the cost. Finally, this can accurately stage the axilla, possibly allowing axillary dissection to be foregone in patients where the SLN is clear

Bacterial Profile and Antimicrobial Susceptibility Pattern in Septicemia Suspected Children and Available Treatment Options

OBJECTIVES Septicaemia (blood poisoning) is one of the chief sources of global morbidity and mortality in pediatric patients and presents with multidrug and extensive drug resistance. This study aims to detect the major causative agents, antimicrobial susceptibility patterns and associated factors of bacteraemia among pediatric patients.METHODOLOGY This retrospective cross-sectional study was done at National Medical Center, Karachi microbiology laboratory. Clinical specimens consist of blood. Blood samples were processed in BACTEC's automated blood culture system, and positive samples were sub-cultured on blood, Mac-Conkey. Final identification was done by API 20E and API 20NE (Biomerieux) and confirmed by MicroScan (Beckman coulter)®. The antimicrobial susceptibility was performed by using Bauer– Kirby disk diffusion method.RESULTS A total of 395 pediatric patients were taken in the study. Out of these patients, 226 (57.2 %) were female. The children with age 1-4 years were highly affected. Almost 50% were handled in emergency and transferred for admission. 36.2% of patients were exposed to intravenous devices. 89 (22.5%) patients had a history of prolonged use of antibiotics. Most patients with pneumonia presented with septicemia as a complication, and were detected by Klebsiella pneumonia (35.4%), Acinetobacter bauminii (25.3%) and Pseudomonas aeruginosa (20.3%).  CONCLUSION The study revealed that gram-negative organisms are the predominant causative organisms of septicaemia. Antibiotic resistance to Carbapenem is gradually increased in the case of Acinetobacter bauminii and Escherichia coli. These issues can be overcome by early detection of microorganisms and establishing antibiotic stewardship

Cytotoxic and antiviral potentials of Euphorbia milii var. splendens leaf against Peste des petits ruminant virus

Purpose: To determine the cytotoxic and antiviral potentials of Euphorbia milii var. splendens leaf against Peste des petits ruminants virus (PPRV). Methods: The methanol extract, as well as n- hexane, chloroform, ethyl acetate, and n- butanol fractions of E. milii leaves were screened for cytotoxic and antiviral activities against PPRV using Vero cell line and 3-(4,5-dimethylthiazol-2-yl)-2,diphenyltetrazolium bromide (MTT) assay. Results: Non-cytotoxic concentrations with cell survival rate (CSP) greater than 50 % were considered virucidal. Methanol extract and fractions produced significant (p < 0.05) effects at all test concentrations against PPRV. The 50 % cytotoxic concentration (CC50) calculated was ≤ 25 µg/mL for extract and fractions. In antiviral assay, ethyl acetate, n-hexane, and n-butanol fractions at all test concentrations ranging from 1.56 - 800 µg/mL were non-virucidal; even at their non-cytotoxic concentrations these fractions did not show antiviral activities. However, the methanol extract and its chloroform fractions showed significant (p < 0.05) virucidal potential. Conclusion: The results suggest that further isolation of antiviral constituents from the fractions may open new horizons for the development of new antiviral agents

Financial development and environmental quality: The way forward

The present paper re-examines the asymmetric impact of financial development on environmental quality in Pakistan for the period 1985Q1 to 2014Q4. A comprehensive index of financial development is generated using Bank- and Stock market-based financial development indicators. The results show that inefficient use of energy adversely affects the environmental quality. This suggests adoption of energy efficient technology at both production and consumption levels. These technologies would be helpful to improve environmental quality, enhance the productivity in long-run and save energy. Bank-based financial development also impedes the environment. The government should encourage lenders to ease the funding for energy sector and allocate financial resources for environment friendly businesses rather than wasting them in consumer financing

Clinical and etiological profile of Complicated Urinary Tract Infection in Children: A health facility-based cross-sectional study

Background: Urinary tract infection (UTI) is known to be the most frequent bacterial infection in the paediatric population. Objective: To determine the clinical profile and etiology of complicated urinary tract infection (UTI) in children. Methods: This cross-sectional study was done at the Department of Nephrology and Neonatology, National Institute of Child Health, Karachi from 1st January 2022 to 30th June 2022. In 241 children of either gender, (male and female) aged up to 15 years having structural or functional anomalies of the kidney and urinary tract or recurrent infection due to underlying kidney or urinary tract abnormalities were enrolled. Demographic and clinical characteristics along with laboratory parameters and etiological agents of complicated UTI were noted. Ultrasonography examination and dimercaptosuccinic acid (DMSA) renal scan (where indicated) were performed. Results: Of 241 children, 179 (74.3%) were male. The mean age was 3.08±3.63 years. Capillary refill time was prolonged in 78 (32.4%) children. Fever/chills, nausea/vomiting, urinary urgency, and dehydration were the most frequently noted clinical presentations reported in 232 (96.2%), 109 (45.2%), 91 (37.8%), and 89 (36.9%) children respectively. Ultrasonography findings were evident of bilateral moderative hydronephrosis in 60 (24.9%) children. E. coli followed by Pseudomonas and Klebsiella species were the most commonly found etiological agents noted in 98 (40.7%), 50 (20.7%), and 40 (16.6%) children respectively. Conclusion: The majority of the children with complicated UTIs were male. Fever/chills, nausea/vomiting, urinary urgency, and dehydration were the most frequently noted clinical presentations. The most commonly observed ultrasonography findings were bilateral moderative hydronephrosis

Erectile dysfunction: prevalence, risk factors and involvement of antihypertensive drugs intervention

Purpose: To explore the literature regarding prevalance, risk factors and the involvement of antihypertensive drugs in erectile dysfunction (ED).Methods: Original research articles, reviews, editorials and case reports published in English language on the prevalence of sexual/erectile dysfunction in hypertensive men taking antihypertensive drugs and risk factors were identified through a search of four bibliographic databases, namely, PubMed, EMBASE, CINAHL and EBSCO Health.Results: Recent analyses suggest that hypertensive men of almost all age groups suffer from ED but it is more prevalent in elderly male patients. The involvement of β-blockers was found to be controversial. Nevertheless, some evidence had been found regarding the use of propranolol in high doses.Conclusion: The present review indicates the need for research to unravel the role of β-blockers in the manifestation of ED in hypertensive males, whom there are no contributory factors such as sedentary lifestyle, aging, stress and anxiety, etc.Keywords: Hypertension, Antihypertensive drugs, β-Blockers, Propranolol, Erectile dysfunction, Life style, Risk factor