Vortex detection and quantum transport in mesoscopic graphene Josephson-junction arrays

We investigate mesoscopic Josephson junction arrays created by patterning superconducting disks on monolayer graphene, concentrating on the high-$T/T_c$ regime of these devices and the phenomena which contribute to the superconducting glass state in diffusive arrays. We observe features in the magnetoconductance at rational fractions of flux quanta per array unit cell, which we attribute to the formation of flux-quantized vortices. The applied fields at which the features occur are well described by Ginzburg-Landau simulations that take into account the number of unit cells in the array. We find that the mean conductance and universal conductance fluctuations are both enhanced below the critical temperature and field of the superconductor, with greater enhancement away from the graphene Dirac point.This work was financially supported by the Engineering and Physical Sciences Research Council, and an NPL/EPSRC Joint Postdoctoral Partnership (RG61493).This is the accepted manuscript. The final version is available at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.91.245418

Marfan syndrome and pregnancy: maternal and neonatal outcomes

Objective To report outcomes in a recent series of pregnancies in women with Marfan syndrome (MFS). Design Retrospective case note review. Setting Tertiary referral unit (Chelsea and Westminster and Royal Brompton Hospitals). Sample Twenty-nine pregnancies in 21 women with MFS between 1995 and 2010. Methods Multidisciplinary review of case records. Main outcome measures Maternal and neonatal mortality and morbidity of patients with MFS and healthy controls. Results There were no maternal deaths. Significant cardiac complications occurred in five pregnancies (17%): one woman experienced a type–A aortic dissection; two women required cardiac surgery within 6 months of delivery; and a further two women developed impaired left ventricular function during the pregnancy. Women with MFS were also more likely to have obstetric complications (OR 3.29, 95% CI 1.30–8.34), the most frequent of which was postpartum haemorrhage (OR 8.46, 95% CI 2.52–28.38). There were no perinatal deaths, although babies born to mothers with MFS were delivered significantly earlier than those born to the control group (median 39 versus 40 weeks of gestation, Mann–Whitney U–test, P = 0.04). These babies were also significantly more likely to be small for gestational age (24% in the MFS group versus 6% in the controls; OR 4.95, 95% CI 1.58–15.55). Conclusions Pregnancy in women with MFS continues to be associated with significant rates of maternal, fetal, and neonatal complications. Effective pre-pregnancy counselling and meticulous surveillance during pregnancy, delivery, and the puerperium by an experienced multidisciplinary team are warranted for women with MFS

Stability Constraints on Classical de Sitter Vacua

We present further no-go theorems for classical de Sitter vacua in Type II string theory, i.e., de Sitter constructions that do not invoke non-perturbative effects or explicit supersymmetry breaking localized sources. By analyzing the stability of the 4D potential arising from compactification on manfiolds with curvature, fluxes, and orientifold planes, we found that additional ingredients, beyond the minimal ones presented so far, are necessary to avoid the presence of unstable modes. We enumerate the minimal setups for (meta)stable de Sitter vacua to arise in this context.Comment: 18 pages; v2: argument improved, references adde

Accretion Disks Around Black Holes: Twenty Five Years Later

We study the progress of the theory of accretion disks around black holes in last twenty five years and explain why advective disks are the best bet in explaining varied stationary and non-stationary observations from black hole candidates. We show also that the recently proposed advection dominated flows are incorrect.Comment: 30 Latex pages including figures. Kluwer Style files included. Appearing in `Observational Evidence for Black Holes in the Universe', ed. Sandip K. Chakrabarti, Kluwer Academic Publishers (DORDRECHT: Holland

A population of luminous accreting black holes with hidden mergers

Major galaxy mergers are thought to play an important part in fuelling the growth of supermassive black holes. However, observational support for this hypothesis is mixed, with some studies showing a correlation between merging galaxies and luminous quasars and others showing no such association. Recent observations have shown that a black hole is likely to become heavily obscured behind merger-driven gas and dust, even in the early stages of the merger, when the galaxies are well separated (5 to 40 kiloparsecs). Merger simulations further suggest that such obscuration and black-hole accretion peaks in the final merger stage, when the two galactic nuclei are closely separated (less than 3 kiloparsecs). Resolving this final stage requires a combination of high-spatial-resolution infrared imaging and high-sensitivity hard-X-ray observations to detect highly obscured sources. However, large numbers of obscured luminous accreting supermassive black holes have been recently detected nearby (distances below 250 megaparsecs) in X-ray observations. Here we report high-resolution infrared observations of hard-X-ray-selected black holes and the discovery of obscured nuclear mergers, the parent populations of supermassive-black-hole mergers. We find that obscured luminous black holes (bolometric luminosity higher than 2x10^44 ergs per second) show a significant (P<0.001) excess of late-stage nuclear mergers (17.6 per cent) compared to a sample of inactive galaxies with matching stellar masses and star formation rates (1.1 per cent), in agreement with theoretical predictions. Using hydrodynamic simulations, we confirm that the excess of nuclear mergers is indeed strongest for gas-rich major-merger hosts of obscured luminous black holes in this final stage.Comment: To appear in the 8 November 2018 issue of Nature. This is the authors' version of the wor

Rain Tourism: A Progressive Opportunity and Challenges for Konkan Tourism

Konkan region is located in Maharashtra state surrounded by Sahyadri hills ranges in the west, metro city Mumbai and suburbs in the north, Goa in the south and mighty Arabian Sea in the east. It enjoys 720 km long coastline, it is one of the unexploited tourism destination in India which has a huge potential to attract and provide a mesmerising service to the tourists. Konkan is blessed with surprisingly natural waterfalls amid green canopy mountains and beautiful popping out Wadis welcoming the tourists with a wonderful gesture of delicious mouth-watering signature delicacies, rich culture and down to earth ethnic hospitality.&nbsp; The waving coconut trees directing the visitors towards the gorgeous emerald virgin beaches, historical forts, ancient temples, mango and beetle nut grooves. It bears all the pre-requisites that perfectly fit into various types of tourism formats like religious tourism, cultural tourism, ethnic tourism, rural tourism, agro tourism, Senior citizen tourism, Adventure tourism, Food tourism, etc. But unfortunately due to heavy rainfall during rainy season it experiences a rock bottom low in terms of tourist flow.&nbsp; Rainy season in Konkan persists from the month of June to the month of September. It has measured more than 4000 mm rainfall at an average last year that is almost 57% above normal rainfall in Maharashtra. Many of the time it observes flood situations. The rainfall trends experienced usually by Konkan region states that June and July are aggressive month with heavy rainfall followed by reduced intensity of rain from August to October. Thus June and July can be focused on adventurous and risk taker topological tourists while August, September and October can be focused on senior citizen and family oriented tourists. &nbsp;The researcher tries to identify a niche kind of tourism opportunity that is rain tourism which will focus on attracting tourists’ inflow during the slack period from various locations of Maharashtra, India and across the globe that have below average or low rainfall at their place. A detailed SWOC analysis of Konkan is done to highlight the challenges and opportunities so it can arise as sustainable and a notable contender in achieving $ 5 trillion economy of India. Konkan can possibly generate lot of opportunities during rainy season to attract domestic and international tourist around the World at a large who have below average or low rainfall during rainy season. Konkan can provide them with a memory to cherish for a lifetime with beautiful jade scenic beauty, aroma of freshness, crabs and frogs moving around with mouth-watering hot snacks and local delicacies. In addition to this it can have value added infrastructure for rain based activities like Mud pies for rain dance, Rain gears loaded heritage walk, Monsoon camping, Rain gauge workshop, Rice farms plantation activity, Ayurveda spa, Rain trek, Horse safari, natural waterfall showers, Open discotheque, Wine and beer appreciation and testing sessions, Government or NGO initiated Food tourism events like Rain food festivals or cookery shows etc., Rain sports like football, volley ball etc., adventure sports like river rafting, Waterfall rappelling and many more. If this opportunity will be converted in to reality will help, the temporary hospitality workforce that is laid-off due to off-season to have hopes of being financially benefitted with job security, locals will have direct and indirect source of income. Due to revenue generation by the government through taxes it will concentrate on developing a safe infrastructure for Konkan region with respect to rainy season. If the above stated opportunities be converted in to reality it will gradually add on to the nations GDP for sure. Konkan has to firstly be optimistic about the concept of rain tourism as history has revealed that rain has always come up with disaster and loss. With the government intervention by developing proper roadways, railway network and proper whether forecast and alerts the situation is getting better. Konkan faces many challenges in many aspects to get this niche tourism concept into reality starting from changing the mind-set of locals favouring this innovative enterprise and gaining their support along with skill development and expertise. Accessibility infrastructure which will be safe and secured like good quality and big roads, specially trained drivers etc. Medical infrastructure including good medical assistance and quick response team. Digital infrastructure like Wi-Fi, mobile network, high speed internet has become the basic necessity presently hence it is required to be developed at least at the tourist destinations. Power failure especially during rainy seasons is a normal, the government needs to find out solution to curb this issue and ensure 24hrs electricity or backups by the hoteliers. Aggressive marketing using digital marketing tools and travel agents networking is very essential to make this seed idea to flourish in a success story. Advertisement will help to create awareness, develop confidence and motivate the potential tourists to opt for it. Government or NGO should initiate with an emergency rescue task support team who can rush in case of any unforeseen calamities. The safety and security concerns need to be properly dealt by the Police department with more check post to control immoral and illegal practices that might occur during rainy season. The researcher has not only explored the potential opportunities and possible challenges during rainy season in Konkan but also has tried to analyse the perception, willingness and acceptance by the probable tourists with the help of well-developed questionnaire through digital survey tools like Google forms etc. The hypothesis made by the researcher has been statistically tested to prove the significance of the concept. Rain tourism concept is an innovative niche avenue that can be applied to all other tourism destinations with heavy rainfall and slack business during that period. With lot of opportunities in the concept, if the challenges faced are dealt in a professional and planned way will give rise to a new transformation. Rain tourism has a great prospective to streamline the economic graph of the destination which goes down during the rainy season and raise it upwards

On nonsupersymmetric \BC^4/\BZ_N, tachyons, terminal singularities and flips

We investigate nonsupersymmetric \BC^4/\BZ_N orbifold singularities using their description in terms of the string worldsheet conformal field theory and its close relation with the toric geometry description of these singularities and their possible resolutions. Analytic and numerical study strongly suggest the absence of nonsupersymmetric Type II terminal singularities (i.e. with no marginal or relevant blowup modes) so that there are always moduli or closed string tachyons that give rise to resolutions of these singularities, although supersymmetric and Type 0 terminal singularities do exist. Using gauged linear sigma models, we analyze the phase structure of these singularities, which often involves 4-dimensional flip transitions, occurring between resolution endpoints of distinct topology. We then discuss 4-dim analogs of unstable conifold-like singularities that exhibit flips, in particular their Type II GSO projection and the phase structure. We also briefly discuss aspects of M2-branes stacked at such singularities and nonsupersymmetric AdS_4\times S^7/\BZ_N backgrounds.Comment: Latex, 43pgs incl. appendices, 2 eps figs, v2. minor clarifications added, to appear in JHE

BPS Spectrum, Indices and Wall Crossing in N=4 Supersymmetric Yang-Mills Theories

BPS states in N=4 supersymmetric SU(N) gauge theories in four dimensions can be represented as planar string networks with ends lying on D3-branes. We introduce several protected indices which capture information on the spectrum and various quantum numbers of these states, give their wall crossing formula and describe how using the wall crossing formula we can compute all the indices at all points in the moduli space.Comment: LaTeX file, 33 pages, 15 figure

On The Stability Of Non-Supersymmetric AdS Vacua

We consider two infinite families of Non-Supersymmetric $AdS_4$ vacua, called Type 2) and Type 3) vacua, that arise in massive IIA supergravity with flux. We show that both families are perturbatively stable. We then examine non-perturbative decays of these vacua to other supersymmetric and non-supersymmetric $AdS_4$ vacua mediated by instantons in the thin wall approximation. We find that many decays are ruled out since the tension of the interpolating domain wall is too big compared to the energy difference in AdS units. In fact, within our approximations no decays of Type 2) vacua are allowed, although some decays are only marginally forbidden. This can be understood in terms of a "pairing symmetry" in the landscape which relate Type 2) vacua with supersymmetric ones of the same energy.Comment: 50 pages, Minor changes in section 2.2.

Implementation of Secure Log Management Over Cloud

A Log records are very important information which is related to activities of systems, applications or networks and these log records having various fields and their syntax. Actually logs are automatically generated on activities that are done and doing by user on system, or on any Applications such as Google Chrome or in networks. These logs are costly and need to any organization for future references such as to identify or finding any problems, to record all events, to find performance, and to investigate malicious activities in systems or networks or in application. So, protection of logs from attackers is required. Hence organization should maintain integrity, confidentiality, and security of logs. The cost to maintain logs for organizations for longer period is very less. Hence, we developed secure log management over cloud to decrease cost as well as provide security of log from attackers. To achieve this, we have done this with the help of Blowfish algorithm to Encrypt log records then SHA-1 is used to provide confidentiality while transmitting and at end point security purpose we used Shamir’s Secret sharing algorithm. DOI: 10.17762/ijritcc2321-8169.150511