Exceptional Points of Degeneracy in Periodic Coupled Waveguides and the Interplay of Gain and Radiation Loss: Theoretical and Experimental Demonstration

We present a novel paradigm for dispersion engineering in coupled transmission lines (CTLs) based on exceptional points of degeneracy (EPDs). We develop a theory for fourth-order EPDs consisting of four Floquet-Bloch eigenmodes coalescing into one degenerate eigenmode. We present unique wave propagation properties associated to the EPD and develop a figure of merit to assess the practical occurrence of fourth-order EPDs in CTLs with tolerances and losses. We experimentally verify for the first time the existence of a fourth EPD (the degenerate band edge), through dispersion and transmission measurements in microstrip-based CTLs at microwave frequencies. In addition, we report that based on experimental observation and the developed figure of merit, the EPD features are still observable in structures that radiate (leak energy away), even in the presence of fabrication tolerances and dissipative losses. We investigate the gain and loss balance regime in CTLs as a mean of recovering an EPD in the presence of radiation and/or dissipative losses, without necessarily resorting to Parity-Time (PT)-symmetry regimes. The versatile EPD concept is promising in applications such as high intensity and power-efficiency oscillators, spatial power combiners, or low-threshold oscillators and opens new frontiers for boosting the performance of large coherent sources

Passively Q-switched fiber lasers using a multi-walled carbon nanotube polymer composite based saturable absorber

We demonstrate a simple, compact and low cost Q-switched fiber lasers based on Erbium-doped fiber (EDF) and Thulium-doped fiber (TDF) to operate at 1534.5 nm and 1846.4 nm, respectively by exploiting a multi-walled carbon nanotubes (MWCNTs) polymer composite film based saturable absorber (SA). The composite is prepared by mixing the MWCNTs homogeneous solution into a dilute polyvinyl alcohol polymer solution before it is left to dry at room temperature to produce thin film. Then the film is sandwiched between two FC/PC fiber connectors and integrated into the laser cavity for Q-switching pulse generation. The EDF laser generates a stable pulse train with repetition rates ranging from 38.11 kHz to 48.22 kHz by varying the 980 nm pump power from 39.0 mW to 65.3 mW. At the 65.3 mW pump power, the pulse width and pulse energy were 5.3 μs and 99.75 nJ, respectively. The TDF laser generates a stable pulse train with 10.38 kHz repetition rate, 17.52 μs pulse width and 11.34 nJ pulse energy at 121.1 mW 800 nm pump power. A higher performance Q switching is expected to be achieved in both fiber lasers with the optimization of the SA and laser cavity

Value of Serum Growth Differentiation Factor 15 in diagnosis of Colorectal Cancer

Background: Colorectal Cancer (CRC) is considered the third most deadly and fourth most commonly diagnosed cancer in the world.Objective: The aim of the present study was to compare serum levels of growth differentiation factor-15 (GDF-15) in patients with CRC and in those healthy control subjects.Patients and methods: The study included 60 subjects that were divided in two groups: Group Ι included 30 patients diagnosed with colorectal cancer and group ΙΙ that included 30 healthy volunteers as control group. They didn`t have any acute or chronic diseases. All subjects of this study were subjected to full history taking, clinical examination and laboratory investigations. The study was conducted at Internal Medicine Department (gastroenterology and endoscopy unit), Faculty of Medicine, Zagazig University. Results: The study comprised 35 males (58.3%) and 25 females (41.7%), with a mean age of 61 ± 9 years. Twenty-six participants were from urban areas (43.3%) and 34 from rural areas (56.7%). Thirteen participants had a suspicious occupational exposure (21.7%) and 27 were smokers (45%). Mean BMI of all participants was 31 ± 6 kg/m2 with no statistically significant differences between the studied groups. Regarding Hb level and GDF-15, there were statistically significant differences between CRC group and control group where Hb was higher in the control group, while GDF15 was higher in CRC group. Conclusion: Growth differentiation factor 15 (GDF-15) could be used as a valuable independent biomarker for screening CRC

Regime Hydraulic Concepts and Equations: The Case of Klang River, Malaysia

Updating and testing of available river regime relationships governing the various factors involved in alluvial river design are presented. Analysis of relevant laboratory and field data, gathered from four gauging stations along the water course of Klang River in Malaysia, were undertaken in order to formulate new regime concepts and equations characterizing the river. The functional formulations, to include the slope, rating and flow equations were achieved by employing dimensional analysis techniques relating the geometry and flow parameter

Studies on drought tolerance in maize inbred lines using morphological and molecular approaches

A set of hundred homozygous maize inbred lines were analyzed for drought toleranceby studying twenty-four traits related to maturity, morphological, physiological, yield, quality and few root traits. Evaluation confirmed a wide range of variability revealing significant response of main effects (lines, irrigations and years and their respective digenic and trigenic interactions). These lines were subjected to different stress regimes over years leading to identification of fifteen elite lines which performed well under droughtstress showing inbuilt drought tolerance. A set of 32 SSR markers, having genome-wide coverage, were chosen for genotyping the inbred lines. These markers generated a total of 239 polymorphic alleles with an average of 7.47 alleles per locus. The minimum and maximum PIC value was 0.886 and 0.608 with a mean of 0.782. The coefficient of genetic dissimilarity ranged from 0.215 to 0.148. DARwin derived cluster analysis grouped 15 elite maize lines in three major clusters with five lines each in cluster-III and II and four lines in cluster-I with KDM-361A as root. Molecular diversity however, confirmed diverse genetic nature of six lines (KDM-372, KDM-343A, KDM-331, KDM-961, KDM-1051 and KDM-1156) showing drought tolerance. Exploitation of identified elite lines in a crossing program involving all possible combinations would help to develop hybrids with inbuilt mechanism to drought tolerance. Markers viz., umc -1766, umc-1478 and phi-061 recorded PIC >8 and alleles per locus more than 9 and therefore, discriminated the set of lines more efficiently. Genotyping data complemented by morpho- hysiological parameters were used to identify a number of pair-wise combinations for the development of mapping population segregating for drought tolerance and potential heterotic pairs for the development of drought tolerant hybrids.

High Frequency of cagA and vacA s1a/m2 Genotype among Helicobacter pylori Infected Gastric Biopsies of Pakistani Children

The vacuolating cytotoxin VacA and cytotoxin associated gene product CagA, encoded by vacA and cagA are major virulence determinants associated with pathogenesis of Helicobacter pylori. The presence and prevalence of two major H. pylori virulence associated genes among gastric biopsies of Pakistani children were investigated in the current study. Fifty one gastric biopsy specimens of children were analysed for 16S rRNA, vacA and cagA genes using PCR. The results showed that 21 (41.2%) biopsies were positive for H. pylori as determined by 16S rRNA PCR. In the 21 H. pylori positive gastric biopsies, 19 (90.5%) showed vacA s1a, 1 (4.75%) was vacA s1b and 1 (4.75%) was vacA s2 whereas, 5 (23.8%) were vacA m1 and 16 (76.2%) were vacA m2. None of the H. pylori positive biopsies carried vacA s1c subtype. The cagA gene was found in 13 (61.9%) of H. pylori infected biopsies and different vacA combinations were found with or without cagA gene. H. pylori was detected with high frequency of cagA while vacA s1a and vacA m2 regions with vacA s1a/m2 genotype were predominant in H. pylori infected gastric biopsies of children

Transcriptional network growing models using motif-based preferential attachment

Understanding relationships between architectural properties of gene-regulatory networks (GRNs) has been one of the major goals in systems biology and bioinformatics, as it can provide insights into, e.g., disease dynamics and drug development. Such GRNs are characterized by their scale-free degree distributions and existence of network motifs – i.e., small-node subgraphs that occur more abundantly in GRNs than expected from chance alone. Because these transcriptional modules represent “building blocks” of complex networks and exhibit a wide range of functional and dynamical properties, they may contribute to the remarkable robustness and dynamical stability associated with the whole of GRNs. Here, we developed network-construction models to better understand this relationship, which produce randomized GRNs by using transcriptional motifs as the fundamental growth unit in contrast to other methods that construct similar networks on a node-by-node basis. Because this model produces networks with a prescribed lower bound on the number of choice transcriptional motifs (e.g., downlinks, feed-forward loops), its fidelity to the motif distributions observed in model organisms represents an improvement over existing methods, which we validated by contrasting their resultant motif and degree distributions against existing network-growth models and data from the model organism of the bacteriumEscherichia coli. These models may therefore serve as novel testbeds for further elucidating relationships between the topology of transcriptional motifs and network-wide dynamical properties

Bubble continuous positive airway pressure as a primary modality of respiratory support in meconium aspiration syndrome

Background: Approximately 3–4% of neonates with meconium-stained amniotic fluid (MSAF) develop meconium aspiration syndrome (MAS), of which nearly 30–50% need continuous positive airway pressure (CPAP) or mechanical ventilation (MV). Objective: The objective of the study was to evaluate the usefulness of bubble CPAP as a respiratory support in neonates admitted with MAS and to enumerate factors affecting the CPAP failure. Materials and Methods: A prospective study was conducted, involving all the neonates born with a history of MSAF with respiratory distress within 6 h of life (Downe’s score 4–7), SpO2 <90% with chest X-ray suggestive of MAS. Bubble CPAP was started with pressure and FiO2 adjusted to maintain a SpO2 between 89% and 95%, maximum pressure limit of 6 cm, and FiO2 of 100%, respectively. CPAP was removed when SpO2 was >90% with FiO2 requirement <25% and when respiratory distress was passive (Respiatory rate <60/min, no or mild retractions and no grunt). The primary outcome was measured in terms of improvement in Downe’s score and clinical condition of neonates. CPAP failure was defined as the need for MV, pulmonary leak syndrome, persistent pulmonary hypertension, and progression of Downe’s score. Results: Downe’s score at the start of CPAP was 6 which decreased to 4, 6 h post-CPAP. There was an improvement in FiO2, RR, and heart rate from 68%, 76/min, and 181/min to 84%, 48/min, and 123/min post-CPAP, respectively. The success rate of CPAP was 77% and failure rate was 23%. Conclusion: Early initiation of CPAP in MAS neonates decreases the need for MV and improves outcomes

Antibiotic Resistance Pattern and Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus Colonization in Burns Unit of a Tertiary Care Hospital in Peshawar, Pakistan

Purpose: To develop strategies for the control of hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) which is a serious threat to burns patients with the aid of molecular studies.Methods: Staphylococcus aureus strains were collected from the Burns Unit of Khyber Teaching Hospital (KTH) Peshawar, Pakistan from July - December 2011. Antibiotic resistance was determined according to the recommendations of Clinical Laboratory Standard Institute (CLSI). Molecular epidemiology of the S. aureus strains were determined by pulse field gel electrophoresis (PFGE).Results: PFGE identified 14 clusters which included 29 different pulso-types prevailing in the Burns Unit. Of the 29 types, 11 contained two or more strains of the same pulso-type. These MRSA isolates  were highly resistant to various kinds of penicillin and cephalosporin (85 – 100 %). Among the important anti-staphylococal agents tested, 17 % of the isolates were resistant to fusidic acid and linezolid. All the 54 strains were susceptible to vancomycin.Conclusion: Several of the same pulso-types prevail in the Burns Unit of KTH. Furthermore, 29 pulsotypes  mong the 54 strains suggest the diversity of the MRSA strains collected from burns patients.Keywords: Epidemiology, Pulso-type, Fusidic acid, Linezolid, Vancomycin, Methicillin-resistant Staphylococcus aureus, Burn