On the Algorithmic Power of Spiking Neural Networks

Spiking Neural Networks (SNN) are mathematical models in neuroscience to describe the dynamics among a set of neurons that interact with each other by firing instantaneous signals, a.k.a., spikes. Interestingly, a recent advance in neuroscience [Barrett-Den\`eve-Machens, NIPS 2013] showed that the neurons' firing rate, i.e., the average number of spikes fired per unit of time, can be characterized by the optimal solution of a quadratic program defined by the parameters of the dynamics. This indicated that SNN potentially has the computational power to solve non-trivial quadratic programs. However, the results were justified empirically without rigorous analysis. We put this into the context of natural algorithms and aim to investigate the algorithmic power of SNN. Especially, we emphasize on giving rigorous asymptotic analysis on the performance of SNN in solving optimization problems. To enforce a theoretical study, we first identify a simplified SNN model that is tractable for analysis. Next, we confirm the empirical observation in the work of Barrett et al. by giving an upper bound on the convergence rate of SNN in solving the quadratic program. Further, we observe that in the case where there are infinitely many optimal solutions, SNN tends to converge to the one with smaller l1 norm. We give an affirmative answer to our finding by showing that SNN can solve the l1 minimization problem under some regular conditions. Our main technical insight is a dual view of the SNN dynamics, under which SNN can be viewed as a new natural primal-dual algorithm for the l1 minimization problem. We believe that the dual view is of independent interest and may potentially find interesting interpretation in neuroscience.Comment: To appear in ITCS 201

A Simple Model for Cavity Enhanced Slow Lights in Vertical Cavity Surface Emission Lasers

We develop a simple model for the slow lights in Vertical Cavity Surface Emission Lasers (VCSELs), with the combination of cavity and population pulsation effects. The dependences of probe signal power, injection bias current and wavelength detuning for the group delays are demonstrated numerically and experimentally. Up to 65 ps group delays and up to 10 GHz modulation frequency can be achieved in the room temperature at the wavelength of 1.3 $\mu$m. The most significant feature of our VCSEL device is that the length of active region is only several $\mu$m long. Based on the experimental parameters of quantum dot VCSEL structures, we show that the resonance effect of laser cavity plays a significant role to enhance the group delays

RISK OF SLEEP DISORDERS IN PATIENTS WITH DECOMPRESSION SICKNESS: A NATIONWIDE, POPULATION-BASED STUDY IN TAIWAN

Background: Decompression sickness (DCS) primarily manifests musculoskeletal pain, cutaneous manifestations, lymphatic symptoms, and neurological symptoms. DCS might affect the central nervous system and induce the stress in the patients, but few studies about the psychiatric morbidity after DCS have been conducted. This study aimed to investigate the association between DCS and the risk of developing psychiatric disorders. Subjects and methods: This study was a population-based, matched cohort design. A total of 738 enrolled patients, with 123 study subjects who had suffered from DCS, and 615 controls matched for sex and age, from the Longitudinal Health Insurance Databank from 2000-2010 in Taiwan, and selected from the National Health Insurance Research Database. After adjusting for the confounding factors, Cox proportional hazards analysis was used to compare the risk of developing psychiatric disorders during the 10 years of follow-up period. Results: Of the study subjects, 10 (8.13%) developed psychiatric disorders when compared to 35 (5.69%) in the control group. The study subjects were more likely to develop psychiatric disorders (crude hazard ratio [HR]: 2.79 (95% CI=1.37-5.69, P<0.01). After adjusting for sex, age, monthly income, urbanization level, geographic region, and comorbidities, the adjusted HR was 3.83 (95% CI=1.60-9.16, P<0.01). Sleep disorders was associated with DCS with the adjusted HR as 5.74 (95% CI=1.04-31.56, P<0.01). Hyperbaric oxygenation therapy was not associated with a lower risk of psychiatric disorders. Conclusions: Patients who suffered from DCS have a 3.8-fold risk of developing psychiatric disorders, and a 5.7-fold risk of sleep disorders. This finding is a reminder for the clinicians that a regular psychiatric follow-up might well be needed for these patients

THE EFFECTS OF FUNGAL MEDIUM ON HATCHING RATE OF BITING MIDGE

The little black mosquitos, Forcipomyia taiwana, bite human and become one of the most annoying pests in Taiwan. Recently, the population of F. taiwana increases and invades urban and countryside. In order to effectively prevent the harassment of F. taiwana, develop control strategy is urgent and necessary. Our study found that the fungal medium influenced the length and width of the F. taiwana eggs. It also significantly decreased the hatching rate of F. taiwana. Besides, this artificial diet was more non-toxic and environment-friendly than general chemical pesticides. Thus, this study provided critical information to develop potentially useful bait of F. taiwana in the future

HPV infection and p53 inactivation in pterygium

PurposeOur recent report indicated that tumor suppressor gene (p53) mutations and protein aberrant expression were detected in pterygium. Inactivation of p53 by Human papillomavirus (HPV) 16/18 E6 plays a crucial role in cervical tumorigenesis. In this study, we further speculate that p53 inactivation may be linked with HPV infection in pterygium pathogenesis. To investigate the involvement of HPV 16/18 E6 in p53 inactivation in pterygium, the association between HPV 16 or HPV 18 infection, the HPV E6 oncoprotein, and p53 protein expression was analyzed in this study.MethodsHPV 16/18 infection was detected by nested-polymerase chain reaction (nested-PCR), the p53 mutation was detected by direct sequencing, and the p53 and the HPV 16/18 E6 proteins were studied using immunohistochemistry on 129 pterygial specimens and 20 normal conjunctivas.ResultsThe HPV 16/18 was detected in 24% of the pterygium tissues (31 of 129) but not in the normal conjunctiva, and the HPV16/18 E6 oncoprotein was detected in 48.3% of HPV 16/18 DNA-positive pterygium tissues (15 of 31). In addition, p53 protein negative expression in pterygium was correlated with HPV16/18 E6 oncoprotein expression but not with a p53 mutation.ConclusionsHPV 16/18 E6 contributes to HPV-mediated pterygium pathogenesis as it is partly involved in p53 inactivation and is expressed in HPV DNA-positive pterygium

Short-Term High-Dose Vitamin C and E Supplementation Attenuates Muscle Damage and Inflammatory Responses to Repeated Taekwondo Competitions: A Randomized Placebo-Controlled Trial

Background: Exercise-induced muscle damage during intensive sport events is a very common issue in sport medicine. Therefore, the purpose is to investigate the effects of short-term high-dose vitamin C and E supplementation on muscle damage, hemolysis, and inflammatory responses to simulated competitive Olympic Taekwondo (TKD) matches in elite athletes. Methods: Using a randomized placebo-controlled and double-blind study design, eighteen elite male TKD athletes were weight-matched and randomly assigned into either a vitamin C and E group (Vit C+E; N = 9) or placebo group (PLA; N = 9). Vit C+E or PLA supplements were taken daily (Vit C+E: 2000 mg/d vitamin C; 1400 U/d vitamin E) for 4 days (3 days before and on competition day) before taking part in 4 consecutive TKD matches on a single day. Plasma samples were obtained before each match and 24-hours after the first match for determination of markers of muscle damage, hemolysis, and systemic inflammatory state. Results: Myoglobin was lower in the Vit C+E group, compared to PLA, during the match day (area under curve, AUC -47.0% vs. PLA, p = 0.021). Plasma creatine kinase was lower in the Vit C+E group (AUC -57.5% vs. PLA, p = 0.017) and hemolysis was lower in the Vit C+E group (AUC -40.5% vs. PLA, p = 0.034). Conclusions: We demonstrated that short-term (4-days) vitamin C and E supplementation effectively attenuated exercise-induced tissue damage and inflammatory response during and after successive TKD matches

Genetic analysis of fish iridoviruses isolated in Taiwan during 2001–2009

To investigate the genetic relationships between field strains of iridoviruses gathered from various fish species in Taiwan, viruses that were collected from 2001 to 2009 were analyzed. Open reading frames encoding the viral major capsid protein (MCP) and adenosine triphosphatase (ATPase) were sequenced for phylogenetic analysis. Our results indicated that iridoviruses from Taiwan aquaculture fishes could be classified into two groups: prior to 2005, the viruses were closely related to members of the genus Ranavirus; and after 2005, they were similar to members of the genus Megalocytivirus. Based on the analysis of MCP amino acid sequences, virus isolates were divided into 4 major genotypes that were related to ISKNV, RSIV, FLIV, and GIV, respectively. Pairwise comparisons of MCP genes showed that the ranavirus was an epidemic pathogen for economically important species in the major production regions and cultured marine fish, while the megalocytivirus isolates were sensitive to host range. In addition, the distribution of synonymous and non-synonymous changes in the MCP gene revealed that the iridoviruses were evolving slowly, and most of the variations were synonymous mutations. The Ka/Ks values were lower than one, and hence, the viruses were under negative selection

The potential impact of primary headache disorders on stroke risk

Distribution of PHDs. (DOC 55 kb

Co-Overexpression of Cyclooxygenase-2 and Microsomal Prostaglandin E Synthase-1 Adversely Affects the Postoperative Survival in Non-small Cell Lung Cancer

IntroductionCyclooxygenase (COX)-2 and microsomal prostaglandin E synthase (mPGES)-1 have been found to be overexpressed in non-small cell lung cancer (NSCLC). The aim of this study was to investigate the expression profiles of COX-2 and mPGES-1 and their correlation with the clinical characteristics and survival outcomes in patients with resected NSCLC.Methods/ResultsSeventy-nine paired adjacent normal-tumor matched samples were prospectively procured from patients undergoing surgery for NSCLC. The protein levels of COX-2 and mPGES-1 were assessed by Western blot analysis. Overexpression in the tumor sample was defined as more than twofold increase in protein expression compared with the corresponding adjacent normal tissue. Co-overexpression of COX-2 and mPGES-1 were further confirmed by immunohistochemistry. COX-2 was overexpressed in 58% and mPGES-1 in 70% of the tumor samples (p < 0.0001). Co-overexpression of mPGES-1 and COX-2 was noted in 43%, and they were unrelated to each other (p = 0.232). Co-overexpression of both proteins was significantly associated with less tumor differentiation (p = 0.046), tumor size larger than 5 cm (p = 0.038), and worse survival status during the follow-up (p = 0.036). Multivariate analysis showed that in addition to overall stage, co-overexpression of both proteins adversely affected the overall (hazard ratio, 2.40; p = 0.045) and disease-free survivals (hazard ratio, 2.27; p = 0.029).ConclusionsOverexpression of either COX-2 or mPGES-1 is common but unrelated in NSCLC. Co-overexpression of both COX-2 and mPGES-1 adversely affects postoperative overall and disease-free survivals