Dual-Mode Time Domain Multiplexed Chirp Spread Spectrum

We propose a dual-mode (DM) time domain multiplexed (TDM) chirp spread spectrum (CSS) modulation for spectral and energy-efficient low-power wide-area networks (LPWANs). DM-CSS modulation that uses both the even and odd cyclic time shifts has been proposed for LPWANs to achieve noteworthy performance improvement over classical counterparts. However, its spectral efficiency (SE) is half of the in-phase and quadrature (IQ)-TDM-CSS scheme that employs IQ components with both up and down chirps, resulting in a SE that is four times relative to Long Range (LoRa) modulation. Nevertheless, the IQ-TDM-CSS scheme only allows coherent detection. Furthermore, it is also sensitive to carrier frequency and phase offsets, making it less practical for low-cost battery-powered LPWANs for Internet-of-Things (IoT) applications. DM-CSS uses either an up-chirp or a down-chirp. DM-TDM-CSS consists of two chirped symbols that are multiplexed in the time domain. One of these symbols consisting of even and odd frequency shifts (FSs) is chirped using an up-chirp. The second chirped symbol also consists of even and odd FSs, but they are chirped using a down-chirp. It shall be demonstrated that DM-TDM-CSS attains a maximum achievable SE close to IQ-TDM-CSS while also allowing both coherent and non-coherent detection. Additionally, unlike IQ-TDM-CSS, DM-TDM-CSS is robust against carrier frequency and phase offsets

Understanding and managing project complexity

This research focuses on project complexity with the aim to better understand it and to highlight the factors that affect/contribute to it. In addition, this research also highlights key project management practices and project critical success factors considered important to manage project complexity/complex projects. The two main motivating factors behind this research were, the lack of understanding of complex projects and the lack of relevance of project management theory to practice, which have been highlighted by many researchers. Since projects in different sectors are increasingly being characterised as complex, this entails a better project management knowledge base focusing on the dynamic, social and complex contexts of projects, so that the interrelationships, interdependencies and uncertainties between different project interfaces can be understood and managed properly. In order to understand this 'project actuality', it was necessary to obtain the views from practitioners working in these project settings and managing project dynamics and intricacies. To establish this pragmatic view, a series of interviews and questionnaire surveys was carried out and all efforts were made to select the participants working on complex projects with complex products falling under the Complex Product Systems (CoPS) category which was the case in the 2nd phase interviews and questionnaire, whereas in the 1st phase practitioners with industrial experience and also involved and/or in the process of getting academic qualification in project management were preferred. The first phase helped in establishing the theoretical and pragmatic perspective and the 2nd phase in refining and validating the findings. The questions were inline with the research focus mentioned earlier.The main findings of the research show that the perception of project complexity and its contributing factors were very much influenced by the project context, i.e. from organization level to work discipline level. No difference in the practitioners' perception of project complexity and its contributing factors was observed among the practitioners based in a similar organization and project setting. Novelty was found to be one of the key project complexity characteristics related to three project elements-people, product and process. In terms of key project management practices and skills considered important in managing project complexity, soft skills were reported useful by majority of the participants. The key processes found useful were either the ones which focused on people or others which helped to manage changes/deviations in projects. Influence and relationship, delegation, flexibility and trust were the main project critical success factors which emerged out of this research for complex projects.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Outcomes of Cranioplasty after Craniectomy

Objective:  Craniectomy is a widely used procedure in neurosurgery that results in more cranioplasties to repair skull defects. The complication rate after cranioplasties seems to be higher than elective craniotomies so this study was conducted to determine the outcome of cranioplasty after craniectomy. Materials & Methods:  The patients included in this study had craniectomy and cranioplasty for any indication. Patients included had variables, such as age, sex, underlying pathology, craniectomy and cranioplasty dates, the material used for cranioplasty (autologous bone or methyl methacrylate), and methods of cranioplasty flap fixation (sutures or titanium plates and screws) follow up period and complications. Results:  It was concluded that patients in the age group of 41 – 60 years (5 cases), males (7 cases), cranioplasty performed after 6 months (5cases) with autologous bone graft (8cases) were associated with more complications. Conclusion:  The overall rate of complications associated with cranioplasties is not negligible, however, early cranioplasty in young patients with the use of polymethyl methacrylate may be associated with less complication rate. Keywords:  Decompressive, Craniectomy, Cranioplasty, Autologous, Polymethyl Methacrylat

Multidisciplinary Management and Outcome of Intradural Extramedullary Spinal Tumors

Introduction/Objective:  About fifteen percent of the primary CNS tumors are intraspinal. About two-thirds of tumors are intradural extramedullary (IDEM). This study was conducted to review the outcome of operative management of intradural extramedullary tumors in correlation with the factors, both clinical & histopathological, influencing the neurology of patients & prognosis. Materials and Methods:  It was a multicenter study including 42 patients conducted from December 2018 to December 2020. All patients were diagnosed by MRI with and without contrast. Patients were surgically treated & analyzed for clinical features i.e., pain by visual analog scale (VAS) & neurology by modified McCormick scale both preoperatively & post-operatively. Clinical features & outcomes were correlated with tumor size & histopathology. p-value < 0.05 was considered significant. Results:  This study included 42 cases. The most common diagnosis was schwannoma (76.19%). The average intradural space occupied at presentation was 82%. The most common location was dorsal (90.4%). The visual analog score for pain (VAS) improved in all patients post-operatively from 7 ± 1.9 to 2 ± 0.8 (p = 0.003) & modified McCormick scale from 3.0 ± 1.3 to 2.0 ± 1.0 (p = 0.005). The preoperative symptoms were correlated with the only size of the tumor occupying the intradural space (VAS p = 0.021, modified McCormick scale p = 0.018). Conclusion:  All the tumors excised showed some improvement in neurological status. Therefore, all patients diagnosed with IDEM should be operated on even if present with prolonged symptoms or severe neurological compromise. Keywords:  Intradural Extramedullary, Meningioma, Schwannoma, Intraspinal

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Technique du traitement de signal pour les systemes de communication optique san fil

The radio-frequency (RF) spectrum is dwindling due to an increase in the demand of wireless applications. Hence, there is substantial demand of alternative spectrum regions for communications to recline the conventional RF spectrum. In this context, optical wireless communications (OWC) is explored as a likely candidate to supplement the RF communications. The current work focuses on impairment mitigation techniques and energy-efficient modulation approaches for OWC. Firstly, the peak-to-average power ratio (PAPR) for optical-orthogonal frequency division multiplexing (O-OFDM) is studied and two decision-directed PAPR reduction techniques are presented. The complexity of these methods is comparatively lower than other PAPR reduction methods, whilst, their performance is likewise analogous with other alternatives. Secondly, an optical-single-carrier frequency division multiple access (O-SCFDMA) approach, referred to as Hermitain symmetry free O-SCFDMA (HSFO-SCFDMA) is proposed, that averts Hermiatian symmetry which is normally expected for other O-OFDM and O-SCFDMA approaches. The simulation results affirm that HSFO-SCFDMA is more efficient than any other O-SCFDMA approach for OWC and manifests the lowest PAPR among the other alternatives. Thirdly, the performance of precoding is analyzed for layered asymmetrically clipped O-OFDM (LACO-OFDM). Two types of precoding are employed, i.e., Fourier transform precoding and Hartley transform precoding. It is established that Hartley transform precoded LACO-OFDM exhibits the lowest PAPR and is less vulnerable to non-linear distortion introduced by the light emitting diodes (LEDs), howbeit, the signal-to-noise ratio (SNR) increase (both electrical and optical) owing to the layered structure is higher than conventional LACO-OFDM.Le spectre radiofréquence (RF) diminue en raison d'une augmentation de la demande d'applications sans fil. Par conséquent, il existe une demande importante de régions de spectre alternatifs pour les communications afin d'incliner le spectre RF conventionnel. Dans ce contexte, les communications optiques sans fil (OWC) sont explorées comme un candidat potentiel pour compléter les communications RF. Le travail actuel se concentre sur les techniques d'atténuation des déficiences et les approches de modulation efficaces en énergie pour OWC. Dans un premier temps, on étudie le rapport de puissance crête à moyenne (PAPR) pour le multiplexage par répartition orthogonale de la fréquence optique (O-OFDM) et on présente deux techniques de réduction de PAPR orientées vers la décision. La complexité de ces méthodes est comparativement plus faible que celle des autres méthodes de réduction PAPR, tandis que leurs performances sont également analogues à celles des autres alternatives. Deuxièmement, une approche d'accès multiple par répartition en fréquence optique-porteuse unique (O-SCFDMA), appelée O-SCFDMA sans symétrie d'Hermitain (HSFO-SCFDMA) est proposée. Ce dernier évite la symétrie hermiatienne normalement attendue pour d'autres O-OFDM et Approches O-SCFDMA. Les résultats de la simulation affirment que HSFO-SCFDMA est plus efficace que toute autre approche O-SCFDMA pour OWC et manifeste le plus faible PAPR parmi les autres alternatives. Troisièmement, la performance du précodage est analysée pour l'O-OFDM (LACO-OFDM) asymétriquement en couches. Deux types de précodage sont utilisés, à savoir le précodage par transformée de Fourier et le précodage par transformée d'Hartley. Il est établi que le LACO-OFDM précodé a transformée Hartley présente le PAPR le plus faible et est moins vulnérable à la distorsion non linéaire introduite par les diodes électroluminescentes (LED), mais le rapport signale sur bruit (SNR) augmente ( électrique et optique à la fois) en raison de la structure en couches qui est plus élevée que le LACO-OFDM conventionnelle

Technique du traitement de signal pour les systemes de communication optique san fil

The radio-frequency (RF) spectrum is dwindling due to an increase in the demand of wireless applications. Hence, there is substantial demand of alternative spectrum regions for communications to recline the conventional RF spectrum. In this context, optical wireless communications (OWC) is explored as a likely candidate to supplement the RF communications. The current work focuses on impairment mitigation techniques and energy-efficient modulation approaches for OWC. Firstly, the peak-to-average power ratio (PAPR) for optical-orthogonal frequency division multiplexing (O-OFDM) is studied and two decision-directed PAPR reduction techniques are presented. The complexity of these methods is comparatively lower than other PAPR reduction methods, whilst, their performance is likewise analogous with other alternatives. Secondly, an optical-single-carrier frequency division multiple access (O-SCFDMA) approach, referred to as Hermitain symmetry free O-SCFDMA (HSFO-SCFDMA) is proposed, that averts Hermiatian symmetry which is normally expected for other O-OFDM and O-SCFDMA approaches. The simulation results affirm that HSFO-SCFDMA is more efficient than any other O-SCFDMA approach for OWC and manifests the lowest PAPR among the other alternatives. Thirdly, the performance of precoding is analyzed for layered asymmetrically clipped O-OFDM (LACO-OFDM). Two types of precoding are employed, i.e., Fourier transform precoding and Hartley transform precoding. It is established that Hartley transform precoded LACO-OFDM exhibits the lowest PAPR and is less vulnerable to non-linear distortion introduced by the light emitting diodes (LEDs), howbeit, the signal-to-noise ratio (SNR) increase (both electrical and optical) owing to the layered structure is higher than conventional LACO-OFDM.Le spectre radiofréquence (RF) diminue en raison d'une augmentation de la demande d'applications sans fil. Par conséquent, il existe une demande importante de régions de spectre alternatifs pour les communications afin d'incliner le spectre RF conventionnel. Dans ce contexte, les communications optiques sans fil (OWC) sont explorées comme un candidat potentiel pour compléter les communications RF. Le travail actuel se concentre sur les techniques d'atténuation des déficiences et les approches de modulation efficaces en énergie pour OWC. Dans un premier temps, on étudie le rapport de puissance crête à moyenne (PAPR) pour le multiplexage par répartition orthogonale de la fréquence optique (O-OFDM) et on présente deux techniques de réduction de PAPR orientées vers la décision. La complexité de ces méthodes est comparativement plus faible que celle des autres méthodes de réduction PAPR, tandis que leurs performances sont également analogues à celles des autres alternatives. Deuxièmement, une approche d'accès multiple par répartition en fréquence optique-porteuse unique (O-SCFDMA), appelée O-SCFDMA sans symétrie d'Hermitain (HSFO-SCFDMA) est proposée. Ce dernier évite la symétrie hermiatienne normalement attendue pour d'autres O-OFDM et Approches O-SCFDMA. Les résultats de la simulation affirment que HSFO-SCFDMA est plus efficace que toute autre approche O-SCFDMA pour OWC et manifeste le plus faible PAPR parmi les autres alternatives. Troisièmement, la performance du précodage est analysée pour l'O-OFDM (LACO-OFDM) asymétriquement en couches. Deux types de précodage sont utilisés, à savoir le précodage par transformée de Fourier et le précodage par transformée d'Hartley. Il est établi que le LACO-OFDM précodé a transformée Hartley présente le PAPR le plus faible et est moins vulnérable à la distorsion non linéaire introduite par les diodes électroluminescentes (LED), mais le rapport signale sur bruit (SNR) augmente ( électrique et optique à la fois) en raison de la structure en couches qui est plus élevée que le LACO-OFDM conventionnelle

RELATIVE CHANGES IN HEPATITIS-C VIRUS RNA TITRE AND SERUM ALT LEVELS BEFORE, DURING AND AFTER TREATMENT WITH INTERFERON AND RIBAVIRIN

ABSTRACT Hepatitis C is commonly treated with Interferon and Ribavirin combination therapy. The aim of this study was to find the relative change in the Hepatitis C virus (HCV) RNA titre and serum alanine aminotransferase (ALT) levels before, during and after completion of treatment with Interferon (IFN) and Ribavirin therapy in HCV positive patients. Patients and Methods: This cross -sectional descriptive study was conducted from May 2010 to August 2010. Seventy hepatitis C patients reporting to the Laboratory of Army Medical College, Rawalpindi, were included in the study. Blood samples were first subjected to centrifugation and stored at -20°C till tested. HCV RNA titre was determined by Real Time PCR while ALT estimation on serum samples was done on Selectra-E by kinetic method. The age, gender and treatment status of the patients was also recorded. Result: In a total of 70 patients, 30% were females while 70% were males. The mean age of patients was 38 ± 11 yrs. On applying, analysis of variance (ANOVA), we found that the change in serum ALT level was significant (F = 6.044 and p = 0.004) while it was not significant in case of HCV RNA (F = 1.93 and p = 0.153) treatment with Inj. IFN and Ribavirin. Conclusion: There is a definite decreasing trend in the serum ALT levels while no definite relationship of the HCV RNA level to the treatment with combination therapy with IFN and Ribavirin

LACO-OFDM with Index Modulation for Optical Wireless Systems

International audienceIn this letter, we propose layered asymmetrically clipped optical-orthogonal frequency-division multiplexing (LACO-OFDM) with index modulation (IM), i.e., LACO-OFDM-IM for optical wireless systems. In classical LACO-OFDM, the spectral leakage because of out-of-band clipping harmonics increases the baseband bandwidth (BB) resulting in lower spectral efficiencies. For LACO-OFDM-IM, we use IM and optimize the BB by filtering the out-of-band clipping harmonics. This amalgamation of IM and BB optimization leads to better spectral efficiency (SE). Simulation results shall affirm that LACO-OFDM-IM achieves higher SE, affords a comprehensive granularity for SE/energy efficiency trade-off, and outperforms classical alternatives in terms of bit-error-rate in both line-of-sight and time-dispersive channels