Hybrid resonant cavities: A route towards phase engineered THz metasurfaces.

Coupled resonant cavities can enable strong photon energy confinement to facilitate the miniaturization of functional photonic devices for applications in designs of sensors, modulators, couplers, waveguides, color filters etc. Typically, the resonances in subwavelength plasmonic cavities rely on the excitation of surface plasmons at specific phase-matching conditions, usually determined by the lattice parameters and constituent material properties. Contrary to this notion, we experimentally demonstrate the control and manipulation of cavity resonances via suitably modifying the split ring resonator geometry in hybrid plasmonic-metasurface (dipole cavity-SRR) configuration without altering the lattice parameters. This results to the excitation of dual resonance peaks. Such dual channel characteristics demonstrate high quality (Q) factor, multi-band resonances, not permissible with typical (unhybridized) plasmonic dipole cavities. We envisage such hybrid meta-cavity designs can become important ingredients for futuristic terahertz devices that can hold the key for sixth generation (6G) communications, designer filters, dual channel sensors etc.

Resonant toroidal metasurface as a platform for thin-film and biomaterial sensing.

Toroidal resonances with weak free-space coupling have recently garnered significant research attraction toward the realization of advanced photonic devices. As a natural consequence of weak free-space coupling, toroidal resonances generally possess a high quality factor with low radiative losses. Because of these backgrounds, we have experimentally studied thin-film sensing utilizing toroidal resonance in a subwavelength planar metasurface, whose unit cell consists of near-field coupled asymmetric dual gap split-ring resonators (ASRRs). These ASRRs are placed in a mirrored configuration within the unit cell. The near-field coupled ASRRs support circulating surface currents in both resonators with opposite phases, resulting in excitation of the toroidal mode. In such a way, excited toroidal resonance can support strong light-matter interactions with external materials (analytes to be detected) placed on top of the metasurface. Further, our study reveals a sensitivity of 30 GHz/RIU while sensing AZ4533 photoresist film utilizing the toroidal mode. Such detection of thin films can be highly beneficial for the development of sensing devices for various biomolecules and dielectric materials that can be spin coated or drop casted on metasurfaces. Hence, the toroidal mode is further theoretically explored towards the detection of avian influenza virus subtypes, namely, H5N2 and H9N2. Our study reveals 6 and 9 GHz of frequency redshifts for H5N2 and H9N2, respectively, in comparison to the bare sample. Therefore, this work shows that toroidal metasurfaces can be a useful platform to sense thin films of various materials including biomaterials.

Could rs4379368 be a genetic marker for North Indian migraine patients with aura?: Preliminary evidence by a replication study.

BACKGROUND: Genome wide association studies (GWAS) have already found different migraine single nucleotide polymorphisms (SNPs). To further check if these variants differ by ethnicity, three single nucleotide polymorphisms (SNPs) (rs4379368, rs10504861and rs11172113) were genotyped here to find association with migraine susceptibility from North Indian population. METHODS AND RESULTS: A case control study in 200 subjects was done by polymerase chain reaction and restriction-fragment-length polymorphism (PCR-RFLP) analysis. Univariate analysis was performed to check the association of different genotypic and allelic frequencies of these variants with migraine and its subtypes. We could not find any statistically relevant differences among frequencies at various levels of these selected SNPs between patients and healthy controls in this study (p > 0.05). However on subgroup analysis for rs4379368 SNP, the CT genotype was higher in migraine with aura (MA) (69.6%) than migraine without aura (MO) (51.9%) or control (42%) (p < 0.05). But this relation was not significant at allelic level. For other two SNPs, statistically significant differences were not observed in any of the two migraine subgroups. CONCLUSIONS: This study was able to associate the role of rs4379368 SNP with migraine susceptibility and suggested that genotype CT in rs4379368 SNP could be a possible genetic marker for MA. More studies with larger sample size are needed to strengthen our results.

rs2651899 variant is associated with risk for migraine without aura from North Indian population.

Recently a GWAS study had identified 38 genomic variants commonly found in humans that influence migraine risk. For further replicate these findings, we selected two SNPs; rs2651899 on chromosome 1p36.32 in PRDM16 gene and rs10166942 on chromosome 2q37.1 close to TRPM8 gene for their associations with migraine in the North Indian population as much work has not been done on these variants before from this population. In this case-control association study, 300 unrelated subjects, including 150 migraineurs (43 migraine with aura and 107 migraine without aura) and 150 healthy controls were selected to collect genomic DNA. Polymerase chain reaction and restriction-fragment-length polymorphism methods were performed for genotyping of these variants. Univariate and multivariate analyses were done to find the association of different genotypes and alleles of these SNPs with migraine and its subgroups. We found a statistically significant difference in migraineurs with control for PRDM16 rs2651899 polymorphism at genotypic (p < 0.05), allelic (p = 0.022; OR 1.462; 95% CI 1.058-2.022) and for dominant model (p = 0.011; OR 1.957; 95% CI 1.169-3.276). A similar trend was observed both on subgroup and gender analysis in migraine without aura (MO) and females respectively for rs2651899 variant. For the other SNP (rs10166942), statistically non-significant differences were reported in the allelic/genotypic frequencies between migraineurs and controls as p > 0.05. However, on subgroup analysis we found statistically significant differences at genotypic (p < 0.05) and dominant models in migraine with aura (MA) and in males with that of entire controls. But no significant association was found at allelic level in both subgroup and gender analysis for rs10166942. This research study showed that rs2651899 is a potential genetic marker for migraine susceptibility in MO and female subgroup at both genotypic and allelic level in the North Indian population and found that rs10166942 variant may be a potential marker for MA and male subgroup. Further work with large sample size is required for these SNPs to understand their functional mechanisms and to strengthen our results.

Health-care utilization and expenditure patterns in the rural areas of Punjab, India.

OBJECTIVE: To determine pattern of health care utilization and extent of out-of-pocket healthcare expenditure in rural areas of Punjab in India. METHODS: Using multi stage sampling procedure, 660 participants were selected from 110 villages, out of all 22 districts; 440 participants had utilized outpatient care in past 15 days, and 220 had been hospitalized in past one year. Pretested semistructured questionnaires were used to enquire about household and healthcare expenditures. Out-of-pocket (OoP) expenditure included only direct costs of healthcare. Sevety seven 77 (12%) participants could not provide expenditures, hence were excluded from analysis. More than 10% of total household expenditure on healthcare was considered catastrophic. RESULTS: Majority of the participants had used public sector health facilities for outpatient (57%) and inpatient (51.5%) care. Public sector facilities were utilized more often for communicable diseases and gynaecological problems whereas private sector services were used more commonly for accidents and non-communicable diseases. Mean healthcare expenditure on outpatient and inpatient healthcare services was Indian Rupees (INR) 8501 and INR 53889 respectively. Expenditure in private sector was significantly higher compared to the public sector facilities. Catastrophic expenditure was incurred by 7% of the households while seeking outpatient care and by 53% while seeking inpatient care. To pay for outpatient and inpatient care, 23.3% and 61.5% of the participants respectively had to borrow money or sell their assets. CONCLUSIONS: Healthcare expenditure places households under considerable financial strain in rural areas of Punjab in India. Improvements of public hospitals may increase their utilization and decrease financial burden.

Association of MTHFR gene polymorphisms with migraine in North Indian population.

Polymorphisms in MTHFR gene are mostly associated with increased levels of homocysteine in the absence of dietary folate and are a risk factor for complex neurovascular diseases like migraine. The aim of present case-control study was to determine the association between MTHFR gene polymorphisms (C667T; rs 1801133, A1298C; rs 1801131) with migraine susceptibility. In total, 100 patients with migraine (23with MA and 77 with MO) and age-sex matched 100 healthy controls were included in this study from OPD of ESIC Medical College & Hospital, Faridabad. Genotyping was done by PCR-RFLP method. Genotypic and allelic frequencies were compared by SPSS 24 version. Genotypic results indicated a non-significant increase in frequencies of CT and TT in C667T SNP in migraine patients with control (52 and 10% vs. 42 and 7%: p > 0.05), but CC genotype in A1298C was found to be a risk factor in migraine patients than controls (30 vs. 17% respectively: p < 0.05). On comparing migraine subclasses, migraine with aura (MA) and without aura (MO) with control groups, the present study suggests that in MTHFR polymorphisms, the prevalence of 677CT genotype and T allele in C667T SNP influences susceptibility to MA (p < 0.05) but not to MO. Meanwhile, CC genotype in A1298C SNP could be a risk factor for migraine patients without aura (p < 0.05).

Haplotyping germline and cancer genomes with high-throughput linked-read sequencing.

Haplotyping of human chromosomes is a prerequisite for cataloguing the full repertoire of genetic variation. We present a microfluidics-based, linked-read sequencing technology that can phase and haplotype germline and cancer genomes using nanograms of input DNA. This high-throughput platform prepares barcoded libraries for short-read sequencing and computationally reconstructs long-range haplotype and structural variant information. We generate haplotype blocks in a nuclear trio that are concordant with expected inheritance patterns and phase a set of structural variants. We also resolve the structure of the EML4-ALK gene fusion in the NCI-H2228 cancer cell line using phased exome sequencing. Finally, we assign genetic aberrations to specific megabase-scale haplotypes generated from whole-genome sequencing of a primary colorectal adenocarcinoma. This approach resolves haplotype information using up to 100 times less genomic DNA than some methods and enables the accurate detection of structural variants.

Role of arsenic and its resistance in nature.

Contamination of the environment with heavy metals has increased drastically over the last few decades. The heavy metals that are toxic include mercury, cadmium, arsenic, and selenium. Of these heavy metals, arsenic is one of the most important global environmental pollutants and is a persistent bioaccumulative carcinogen. It is a toxic metalloid that exists in two major inorganic forms: arsenate and arsenite. Arsenite disrupts enzymatic functions in cells, while arsenate behaves as a phosphate analog and interferes with phosphate uptake and utilization. Despite its toxicity, arsenic may be actively sequestered in plant and animal tissues. Various microbes interact with this metal and have shown resistance to arsenic exposure, and they appear to possess the ars operon for arsenic resistance consisting of three to five genes, i.e., arsRBC or arsRDABC, organized into a single transcriptional unit; some microbes even use it for respiration. Microbial interactions with metals may have several implications for the environment. Microbes may play a role in cycling of toxic heavy metals and in remediation of metal-contaminated sites. There is a correlation between tolerance to heavy metals and antibiotic resistance, a global problem currently threatening the treatment of infections in plants, animals, and humans. The purpose of this review is to highlight the nature and role of toxic arsenic in bacterial systems and to discuss the various genes responsible for this heavy-metal resistance in nature and the mechanisms to detoxify this element.

Diversity of arsenate reductase genes (arsC Genes) from arsenic-resistant environmental isolates of E. coli.

A polymerase chain reaction (PCR) approach was used to assess the occurrence and diversity of arsenate reductase gene (arsC gene) in arsenic-resistant environmental E. coli strains. For this purpose, two different sets of primers were designed for the specific amplification of approximately 370-bp fragments from the arsC gene. These primers were used to screen a collection of 25 environmental arsenic-resistant strains isolated from different geographical regions of India, as well as Bangladesh. The PCR results showed that 17 out of the 25 environmental isolates (68%) contained a gene related to the arsC family. Phylogenetic analysis of the protein sequences deduced from the amplicons indicated a prevalence of arsC genes in the isolated strains. A significant divergence in the DNA sequence was found in the arsC genes among As-resistant environmental E. coli strains from this study, and arsenic resistance, a genetic character, arose from a common ancestral background.