Geometric Network Creation Games

Network Creation Games are a well-known approach for explaining and analyzing the structure, quality and dynamics of real-world networks like the Internet and other infrastructure networks which evolved via the interaction of selfish agents without a central authority. In these games selfish agents which correspond to nodes in a network strategically buy incident edges to improve their centrality. However, past research on these games has only considered the creation of networks with unit-weight edges. In practice, e.g. when constructing a fiber-optic network, the choice of which nodes to connect and also the induced price for a link crucially depends on the distance between the involved nodes and such settings can be modeled via edge-weighted graphs. We incorporate arbitrary edge weights by generalizing the well-known model by Fabrikant et al.[PODC'03] to edge-weighted host graphs and focus on the geometric setting where the weights are induced by the distances in some metric space. In stark contrast to the state-of-the-art for the unit-weight version, where the Price of Anarchy is conjectured to be constant and where resolving this is a major open problem, we prove a tight non-constant bound on the Price of Anarchy for the metric version and a slightly weaker upper bound for the non-metric case. Moreover, we analyze the existence of equilibria, the computational hardness and the game dynamics for several natural metrics. The model we propose can be seen as the game-theoretic analogue of a variant of the classical Network Design Problem. Thus, low-cost equilibria of our game correspond to decentralized and stable approximations of the optimum network design.Comment: Accepted at 31st ACM Symposium on Parallelism in Algorithms and Architectures (SPAA '19). 33 pages, 11 figure

Young stellar population and ongoing star formation in the HII complex Sh2-252

In this paper an extensive survey of the star forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population as well as to understand the structure and star formation history. This complex is composed of five embedded clusters associated with the sub-regions A, C, E, NGC 2175s and Teu 136. Using 2MASS-NIR and Spitzer-IRAC, MIPS photometry we identified 577 young stellar objects (YSOs), of which, 163 are Class I, 400 are Class II and 14 are transition disk YSOs. Spatial distribution of the candidate YSOs shows that they are mostly clustered around the sub-regions in the western half of the complex, suggesting enhanced star formation activity towards its west. Using the spectral energy distribution and optical colour-magnitude diagram based age analyses, we derived probable evolutionary status of the sub-regions of Sh2-252. Our analysis shows that the region A is the youngest (~ 0.5 Myr), the regions B, C and E are of similar evolutionary stage (~ 1-2 Myr) and the clusters NGC 2175s and Teu 136 are slightly evolved (~ 2-3 Myr). Morphology of the region in the 1.1 mm map shows a semi-circular shaped molecular shell composed of several clumps and YSOs bordering the western ionization front of Sh2-252. Our analyses suggest that next generation star formation is currently under way along this border and that possibly fragmentation of the matter collected during the expansion of the HII region as one of the major processes responsible for such stars. We observed the densest concentration of YSOs (mostly Class I, ~ 0.5 Myr) at the western outskirts of the complex, within a molecular clump associated with water and methanol masers and we suggest that it is indeed a site of cluster formation at a very early evolutionary stage, sandwiched between the two relatively evolved CHII regions A and B.Comment: 19 pages, 13 figures, Accepted for publication in MNRA

Multiwavelength Study of NGC 281 Region

We present a multiwavelength study of the NGC 281 complex which contains the young cluster IC 1590 at the center, using deep wide-field optical UBVI_c photometry, slitless spectroscopy along with archival data sets in the near-infrared (NIR) and X-ray. The extent of IC 1590 is estimated to be ~6.5 pc. The cluster region shows a relatively small amount of differential reddening. The majority of the identified young stellar objects (YSOs) are low mass PMS stars having age <1-2 Myr and mass 0.5-3.5 M_\odot. The slope (\Gamma) of the mass function for IC 1590, in the mass range 2 < M/M_\odot \le 54, is found to be -1.11+-0.15. The slope of the K-band luminosity function (0.37+-0.07) is similar to the average value (~0.4) reported for young clusters. The distribution of gas and dust obtained from the IRAS, CO and radio maps indicates clumpy structures around the central cluster. The radial distribution of the young stellar objects, their ages, \Delta(H-K) NIR-excess, and the fraction of classical T Tauri stars suggest triggered star formation at the periphery of the cluster region. However, deeper optical, NIR and MIR observations are needed to have a conclusive view of star formation scenario in the region. The properties of the Class 0/I and Class II sources detected by using the Spitzer mid-infrared observations indicate that a majority of the Class II sources are X-ray emitting stars, whereas X-ray emission is absent from the Class 0/I sources. The spatial distribution of Class 0/I and Class II sources reveals the presence of three sub-clusters in the NGC 281 West region.Comment: 29 pages, 21 figures and 11 tables, Accepted for the publication in PAS

Optical and Near-infrared survey of the stellar contents associated with the star-forming Complex Sh2-252

We present the analyses of the stellar contents associated with the HII region Sh2-252 using UBVRI photometry, slit and slitless spectroscopy along with the NIR data from 2MASS for an area ~1 degree x 1 degree. We studied the sub-regions of Sh2-252 which includes four compact-HII (CHII) regions, namely A, B, C and E and two clusters NGC 2175s and Teutsch 136 (Teu 136). Of the fifteen spectroscopically observed bright stars, eight have been identified as massive members of spectral class earlier than B3. From the spectro-photometric analyses, we derived the average distance of the region as 2.4+/-0.2 kpc and the reddening of the massive members is found to vary between 0.35 to 2.1 mag. We found that NGC 2175s and Teu 136, located towards the eastern edge of the complex are the sub-clusters of Sh2-252. The stellar surface density distribution in K-band shows clustering associated with the regions A, C, E, NGC 2175s and Teu 136. We have also identified the candidate ionizing sources of the CHII regions. 61 H_alpha emission sources are identified using slitless spectroscopy. The distribution of the H_alpha emission sources and candidate YSOs with IR excess on the V/(V-I) CMD shows that a majority of them have approximate ages between 0.1 - 5 Myr and masses in the range of 0.3 - 2.5 M_sun. The CMDs of the candidate YSOs in the individual regions also show an age spread of 0.1 - 5 Myr for each of them. We calculated the KLFs for the sub-regions A, C, E, NGC 2175s and Teu 136. Within errors, the KLFs for all the sub-regions are found to be similar and comparable to that of young clusters of age < 5 Myr. We also estimated the mass functions (MFs) of the PMS sample of the individual regions in the mass range of 0.3 - 2.5 M_sun. In general, the slopes of the MFs of all the sub-regions are found comparable to the Salpeter value.Comment: published in MNRA

Seaweeds A Potential Source for Functional Foods

Seaweeds are microalgae growing in coastal regions and resistant to salinity. Seaweeds are rich resources of natural nutrients some of which cannot be obtained from terrestrial plants. Bioactive compounds of seaweeds such as sulphated polysaccharides, peptides, minerals, phlorotannins, carotenoids and sulfolipids have proven health benefits against various diseases. Traditionally, seaweeds are used as folk medicine for treating diseases like goiter, wounds, burns, rashes, inflammation, diabetes and also gaining attention of pharmaceutical industries due to their anti-cancer, anti-aging, anti-angiogenesis, anti-bacterial, anti-viral and antioxidant properties. Seaweeds polysaccharides have wide applications in foods as well as in pharmaceutical industry due to their bio-chemical properties such as stabilizer, emulsifier and gelling property. In food industry, seaweed polysaccharides are used as a functional ingredient in many products such as frozen foods, ice-cream, jam, jelly, beverages etc. Several commercial food preparations from seaweeds are also available in the market such as sea salt, nori snack wasabi, pink rock salt, seaweed thins toasted coconuts, crunchy seaweed chips, raw unroasted seaweed under different brand names. The present review is a compilation of nutritional, pharmacological and food properties of seaweeds along with its potential towards development of functional foods

Research Notes : India : Intra-plant variation in mutation frequency and spectrum in soybean

Upadhyaya (1976) observed that the number of mutant plants was exceedingly low in segregating M2 progenies in soybean. In M3 progenies of normal M2 plants, the number of segregating progenies was also not very high as compared with nonsegregating progenies. But, all the segregating progenies in MJ generation showed an excellent fit to the 3 normal:l mutant ratio, indicating mutant as a monogenic recessive trait. Such a situation was encountered in many cases of albino, yellow leaf, crinkled leaf, and sterile mutants

Role Of Social & Psychological Factors In Drug Default In Patients Of Pulmonary Tuberculosis

Research Problem: What is the influence of social and psychological factors on drug default in patients of pul­monary tuberculosis? Objective: To assess the role of social and psychological factors in drug default in patients of pulmonary tubercu­losis. Study Design: Hospital - based study by questionnaire method Setting and Participants: Patients of pulmonary tubercu­losis attending Out Patient Department of Tuberculosis and Respiratory Diseases, J.N. Medical College Hospital, A.M.U., Aligarh. Sample Size: 136 defaulters and 86 treated cases of pulmonary tuberculosis. Study Variables: Social factors, psychological factors, drug default and pulmonary tuberculosis. Outcome Variables: Association of social and psycho­logical factors with drug default in pulmonary tuberculo­sis patients. Statistical Analysis: By chi - square test and significance at 5% level. Result: Important social factors influencing drug default were joint family (74.27%), lack of money (22.06%) and uncooperative family (11.7%). Psychiatric morbidity among defaulters was significantly high (68.39%). Conclusion: Patient compliance depends on many psy­chological (e.g. psychiatric morbidity, type of personal­ity), and sociological,factors (including economic status of patient, nature of family, its environment, interaction between patient and doctor and patient's own attitude and idea about his disease). Age, sex, residence, religion and education did not show any significant contribution towards drug default

Single grain (LRE)-Ba-Cu-O superconductors fabricated by top seeded melt growth in air

We have recently reported a practical processing method for the fabrication in air of large, single grain (LRE)-Ba-Cu-O [where LRE Nd, Sm, Eu and Gd] bulk superconductors that exhibit high Tc and high Jc. The process is based initially on the development of a new type of generic seed crystal that can promote effectively the epitaxial nucleation of any (RE)-Ba-Cu-O system and, secondly, by suppressing the formation of (LRE)/Ba solid solution in a controlled manner within large LRE-Ba-Cu-O grains processed in air. In this paper we investigate the degree of homogeneity of large grain Sm-Ba-Cu-O superconductors fabricated by this novel process. The technique offers a significant degree of freedom in terms of processing parameters and reproducibility in the growth of oriented single grains in air and yields bulk samples with significantly improved superconducting and field-trapping properties compared to those processed by conventional top seeded melt growth (TSMG)

Arthroscopic resection of dorsal wrist ganglion

Background: The management of dorsal wrist ganglion ranges from benign neglect to surgical excision. The purpose of this study was to study the results of arthroscopic resection of dorsal wrist ganglion.Methods: Twenty one patients who had undergone arthroscopic dorsal wrist ganglion excision and a minimum of 3 months follow up were included. The preoperative complaint of cosmesis, pain, and duration of swelling, wrist range of motion and size of the ganglion were noted. The duration the patient took to return to a painless wrist with full range of motion was noted. Patient satisfaction with respect to cosmesis and function was noted.Results: The mean age was 23.3 years (range: 13 to 35 years). Pre-operative wrist pain was present in 17 patients and cosmesis was a complaint in 18 patients. 5 patients had a pre-operative restricted range of motion. The mean duration and size of the ganglion was 2.6 months (range: 2 to 4 months) and1.8cm (range: 1 to 3 cm) respectively. The mean duration of follow up was 14.6 months (range: 3 to 24 months). Arthroscopically, dorsal synovitis was present in 10 patients, triangular-fibro-cartilage-complex (TFCC) tear in 2 patients and chondral damage in 1 patient. The ganglion stalk was visualized in 14 patients. Complete painless wrist range of motion was obtained by 20 patients by 3 weeks post-operative.  One patient had a recurrence. All the remaining patients were satisfied cosmetically and functionally with the results.Conclusions: Arthroscopic resection is an effective treatment modality for symptomatic dorsal wrist ganglion with good functional and cosmetic results