Coded Index Modulation for Non-DC-Biased OFDM in Multiple LED Visible Light Communication

Use of multiple light emitting diodes (LED) is an attractive way to increase spectral efficiency in visible light communications (VLC). A non-DC-biased OFDM (NDC OFDM) scheme that uses two LEDs has been proposed in the literature recently. NDC OFDM has been shown to perform better than other OFDM schemes for VLC like DC-biased OFDM (DCO OFDM) and asymmetrically clipped OFDM (ACO OFDM) in multiple LEDs settings. In this paper, we propose an efficient multiple LED OFDM scheme for VLC which uses {\em coded index modulation}. The proposed scheme uses two transmitter blocks, each having a pair of LEDs. Within each block, NDC OFDM signaling is done. The selection of which block is activated in a signaling interval is decided by information bits (i.e., index bits). In order to improve the reliability of the index bits at the receiver (which is critical because of high channel correlation in multiple LEDs settings), we propose to use coding on the index bits alone. We call the proposed scheme as CI-NDC OFDM (coded index NDC OFDM) scheme. Simulation results show that, for the same spectral efficiency, CI-NDC OFDM that uses LDPC coding on the index bits performs better than NDC OFDM

Generalized Spatial Modulation in Indoor Wireless Visible Light Communication

In this paper, we investigate the performance of generalized spatial modulation (GSM) in indoor wireless visible light communication (VLC) systems. GSM uses $N_t$ light emitting diodes (LED), but activates only $N_a$ of them at a given time. Spatial modulation and spatial multiplexing are special cases of GSM with $N_{a}=1$ and $N_{a}=N_t$, respectively. We first derive an analytical upper bound on the bit error rate (BER) for maximum likelihood (ML) detection of GSM in VLC systems. Analysis and simulation results show that the derived upper bound is very tight at medium to high signal-to-noise ratios (SNR). The channel gains and channel correlations influence the GSM performance such that the best BER is achieved at an optimum LED spacing. Also, for a fixed transmission efficiency, the performance of GSM in VLC improves as the half-power semi-angle of the LEDs is decreased. We then compare the performance of GSM in VLC systems with those of other MIMO schemes such as spatial multiplexing (SMP), space shift keying (SSK), generalized space shift keying (GSSK), and spatial modulation (SM). Analysis and simulation results show that GSM in VLC outperforms the other considered MIMO schemes at moderate to high SNRs; for example, for 8 bits per channel use, GSM outperforms SMP and GSSK by about 21 dB, and SM by about 10 dB at $10^{-4}$ BER

A systematic review of brachial plexus injuries after caesarean birth: challenging delivery?

BACKGROUND: Caesarean section (CS) is widely perceived as protective against obstetric brachial plexus injury (BPI), but few studies acknowledge the factors associated with such injury. The objectives of this study were therefore to aggregate cases of BPI after CS, and to illuminate risk factors for BPI. METHODS: Pubmed Central, EMBASE and MEDLINE databases were searched using free text: (“brachial plexus injury” or “brachial plexus injuries” or “brachial plexus palsy” or “brachial plexus palsies” or “Erb’s palsy” or “Erb’s palsies” or “brachial plexus birth injury” or “brachial plexus birth palsy”) and (“caesarean” or “cesarean” or “Zavanelli” or “cesarian” or “caesarian” or “shoulder dystocia”). Studies with clinical details of BPI after CS were included. Studies were assessed using the National Institutes for Healthy Study Quality Assessment Tool for Case Series, Cohort and Case-Control Studies. MAIN RESULTS: 39 studies were eligible. 299 infants sustained BPI after CS. 53% of cases with BPI after CS had risk factors for likely challenging handling/manipulation of the fetus prior to delivery, in the presence of considerable maternal or fetal concerns, and/or in the presence of poor access due to obesity or adhesions. CONCLUSIONS: In the presence of factors that would predispose to a challenging delivery, it is difficult to justify that BPI could occur due to in-utero, antepartum events alone. Surgeons should exercise care when operating on women with these risk factors

Single tertiary care centre experience of ovarian granulosa cell tumour in Chennai, India: a retrospective analysis

Background: Granulosa cell tumours of ovary are rare sex-cord stromal tumours characterized by long natural history and favourable prognosis. The present study was done to evaluate the clinical presentation, treatment, outcome, and prognostic factors for patients diagnosed as granulosa cell tumours.Methods: A Retrospective study of Granulosa cell tumour of the ovary was done for a period of five years from January 2011 to December 2015 at a tertiary care centre, Institute of Obstetrics and Gynaecology, Madras Medical College, Chennai. The clinical data and the treatment details were retrieved from the records of medical oncology department and the data were analysed.Results: Twenty five patients were diagnosed as granulose cell tumours of ovary during the study period. The median patient age was 48 years. The most common clinical presentation at diagnosis was vaginal bleeding (76%) followed by abdominal pain (40%). Mean tumor size was 9.6cm. The majority of patients were diagnosed in FIGO stage Ia (84%, n = 21). Thirteen patients (52%) underwent complete staging laparotomy. Twenty three patients (92%) had Adult Granulosa cell tumour. Two patients (8%)had juvenile Granulosa cell tumour. After surgery, all patients were put on observation except two patients who received adjuvant chemotherapy (EP: Etoposide, Cisplatin). The median followup period was 48 months. Five patients (20%) had recurrence; The average time to relapse was 29.6 months. Patients who had tumour size more than 9.7cm had more recurrence events (Hazard Ratio(HR):1.058), but their association is not significant (P value-0.839). The association between menopausal status, torsion of tumour mass, tumour stage with recurrence rate were not significant. The estimated mean overall survival was 84.8 months. Following univariate Cox regression modeling, survival appeared to be independent of age range, post operative residual tumour and the FIGO stage.Conclusions: Granulosa cell tumours of ovary are rare, often diagnosed in early stage. Patients who had tumour size of more than 9.7cm had more recurrence events. A prolonged post therapeutic follow-up is necessary to pick up the late relapses

An interesting case of metastatic brain abscess

Klebsiella pneumoniae is a Gram-negative, non-motile, lactose fermenting, aerobic rod-shaped bacterium with three different subspecies, K. pneumoniae, Klebsiella ozaenae, and Klebsiella rhinoscleromatis. Here, we report the case of a 32-year-old male, chronic alcoholic presented with fever, hemoptysis, and headache of 20 days duration. Over a period of 4 days, the patient worsened with the development of altered sensorium and respiratory distress, connected to a mechanical ventilator. Computed tomography and chest X-ray showed consolidation involving the left lower lobe with an air-fluid level. Magnetic resonance imaging brain showed multiple metastatic brain abscess involving cerebrum and cerebellum and culture reports of sputum and blood showed K. pneumoniae. The patient was started on antibiotics along with anti-tubercular drugs. In spite of effective management, the patient developed recurrent episodes of hemoptysis and died of respiratory failure. For the concomitant involvement of both cerebrum and cerebellum for the first time

Vanishing headache in a young female: An interesting case report

Headache is one of the most common neurological symptom occurring worldwide. Here, we present a unique case of secondary headache in a young female which got reversed with appropriate treatment. A young female who presented with a severe subacute unilateral left-sided intractable headache with papilledema and obstructive hydrocephalus was found to have 4th ventricular neurocysticercosis causing obstruction of the foramen of Magendi and Luschka, relieved on timely surgical excision and with medical management. This case is reported to highlight the rare causes of secondary headache and various presentations of neurocysticercosis, in endemic areas like India as it causes neurological morbidity which can be alleviated on appropriate treatment, thereby preventing economic hardship and improving the quality of life

AI-Based Enhanced Time Cost-Effective Cloud Workflow Scheduling

In this paper, two scheduling algorithms are presented, namely, timeconstrained early-deadline cost-effective algorithm (TECA) to schedule these time-sensitive workflows at the lowest cost and versatile time-cost algorithm (VTCA) which consider both time and cost constraints; these algorithms considerably enhance the earlier algorithms. TECA schedules activities to be completed as soon as possible and optimizes the costs in resource provisioning. VTCA supports quality of service (QoS)-based scheduling, keeping a balance between completion time and cost for the selected QoS level. Both algorithms schedule tasks of the same height within the minimum completion time (using Max-Min algorithm). The tasks get scheduled on new resources only when their completion times are more than the calculated minimum completion times for the given resource. CloudSim-based results show that our algorithms minimize completion time better than other popular algorithms, in addition to reducing costs. The modeling for costs satisfies the criteria of earliest completion time

Potentially toxic element (PTEs) related health risk assessment from air conditioner filter dust in and around Chennai metropolitan

1078-1088We report the health risk assessment of air conditioner filter dust collected from different parts of Chennai city, Southern India, using geochemistry and magnetic properties as proxy. The particle size analysis indicates dust particles range from 0.5 μm to 955 μm and the dust grains falling in the range between 30 to 40 μm. The XRD results indicate that the dust samples contain magnetite, hematite, goethite, and trace elements. The hazard index (HI) of trace elements for child and adult determined in our study shows the probable risk for elements as: Cr > Pb > Ni > Cu > Zn. The daily exposure for inhalation [carcinogenic and non-carcinogenic LDDinh] and cancer risk for inhalation (CRinh) were showing high risk and health impact for Cr followed by Ni. It is suggested from the study that higher ventilation rate assisted by means of a mechanical system and use of air conditioners with regular cleaning can improve the living conditions in the Metropolitan areas

Undescended testis: 513 patients’ characteristics, age at orchidopexy and patterns of referral

10.1136/archdischild-2013-305225Archives of Disease in Childhood995401-40

Unraveling the diverse nature of service quality in a sharing economy: a social exchange theory perspective of Airbnb accommodation

This is an accepted manuscript of an article published by Emerald in International Journal of Contemporary Hospitality Management on 11/09/2017, available online: https://doi.org/10.1108/IJCHM-08-2016-0420 The accepted version of the publication may differ from the final published version.Purpose- This study investigates customers’ perceptions of the service quality facets of Airbnb accommodation using social exchange theory as a suitable conceptual framework to explain aspects of interactivity between guests and hosts. Design/methodology/approach- A self-administered questionnaire consisting of 25 accommodation- specific service quality attributes, structured according to Akbaba’s (2006) measurement scale and based on the service quality hierarchical conceptualization described by Brady and Cronin (2001) and Cronin and Taylor (1992), was distributed to Airbnb international guests visiting Phuket, Thailand. The sample was chosen through a two-stage sampling process and the PLS-SEM technique was used for data analysis. Findings- The results showed that convenience and assurance are critical contributors to the measurement of service quality in remote Airbnb lodgings. The findings further revealed that Airbnb guests are mainly interested in lodgings which have access to certain tourist sights, and in easily accessible information and efficient resolution of problems during their stay. We also found that guests greatly value the convenience and flexibility offered by Airbnb, and that they particularly appreciate the warm hospitality provided by the hosts. Finally, Airbnb guests have very low expectations of the amenities and services available at the lodgings. Research limitations/implications-Airbnb is one of the most well-known examples of hospitality in the sharing economy and results cannot be generalized to similar accommodation providers in sharing economies. Despite the appropriateness of using the measurement tool provided by Akbaba (2006), it is only one option among others for measuring service quality. Practical implications- The current study can assist hosts in gaining better knowledge of guests’ decision making processes and in designing effective marketing strategies by focusing on guests’ requirements in terms of service quality. The effective use of competitive strengths and the prioritization of business resources would potentially enhance guests’ positive experiences at the accommodation and at the destination. Originality/value-Limited numbers of studies have focused on the sharing economy and hospitality and in particular on Airbnb and this is the first study with a focus on service quality issues in terms of Airbnb accommodation