Decay of Unstable D-branes with Electric Field

Using the techniques of two dimensional conformal field theory we construct time dependent classical solutions in open string theory describing the decay of an unstable D-brane in the presence of background electric field, and explicitly evaluate the time dependence of the energy momentum tensor and the fundamental string charge density associated with this solution. The final decay product can be interpreted as a combination of stretched fundamental strings and tachyon matter.Comment: 35 pages, LaTe

Non-BPS D-Branes in Light-Cone Green-Schwarz Formalism

Non-BPS D-branes are difficult to describe covariantly in a manifestly supersymmetric formalism. For definiteness we concentrate on type IIB string theory in flat background in light-cone Green-Schwarz formalism. We study both the boundary state and the boundary conformal field theory descriptions of these D-branes with manifest SO(8) covariance and go through various consistency checks. We analyze Sen's original construction of non-BPS D-branes given in terms of an orbifold boundary conformal field theory. We also directly study the relevant world-sheet theory by deriving the open string boundary condition from the covariant boundary state. Both these methods give the same open string spectrum which is consistent with the boundary state, as required by the world-sheet duality. The boundary condition found in the second method is given in terms of bi-local fields that are quadratic in Green-Schwarz fermions. We design a special ``doubling trick'' suitable to handle such boundary conditions and prescribe rules for computing all possible correlation functions without boundary insertions. This prescription has been tested by computing disk one-point functions of several classes of closed string states and comparing the results with the boundary state computation.Comment: 47 pages, 1 figure. Typos corrected, references added and slight modification of certain explanation made. Version accepted for publication in JHE

On a coordinate independent description of string worldsheet theory

We study worldsheet conformal invariance for bosonic string propagating in a curved background using the hamiltonian formalism. In order to formulate the problem in a background independent manner we first rewrite the worldsheet theory in a language where it describes a single particle moving in an infinite-dimensional curved spacetime. This language is developed at a formal level without regularizing the infinite-dimensional traces. Then we adopt DeWitt's (Phys.Rev.85:653-661,1952) coordinate independent formulation of quantum mechanics in the present context. Given the expressions for the classical Virasoro generators, this procedure enables us to define the coordinate invariant quantum analogues which we call DeWitt-Virasoro generators. This framework also enables us to calculate the invariant matrix elements of an arbitrary operator constructed out of the DeWitt-Virasoro generators between two arbitrary scalar states. Using these tools we further calculate the DeWitt-Virasoro algebra in spin-zero representation. The result is given by the Witt algebra with additional anomalous terms that vanish for Ricci-flat backgrounds. Further analysis need to be performed in order to precisely relate this with the beta function computation of Friedan and others. Finally, we explain how this analysis improves the understanding of showing conformal invariance for certain pp-wave that has been recently discussed using hamiltonian framework.Comment: 32 pages, some reorganization for more elaborate explanation, no change in conclusio

"The fruits of independence": Satyajit Ray, Indian nationhood and the spectre of empire

Challenging the longstanding consensus that Satyajit Ray's work is largely free of ideological concerns and notable only for its humanistic richness, this article shows with reference to representations of British colonialism and Indian nationhood that Ray's films and stories are marked deeply and consistently by a distinctively Bengali variety of liberalism. Drawn from an ongoing biographical project, it commences with an overview of the nationalist milieu in which Ray grew up and emphasizes the preoccupation with colonialism and nationalism that marked his earliest unfilmed scripts. It then shows with case studies of Kanchanjangha (1962), Charulata (1964), First Class Kamra (First-Class Compartment, 1981), Pratidwandi (The Adversary, 1970), Shatranj ke Khilari (The Chess Players, 1977), Agantuk (The Stranger, 1991) and Robertsoner Ruby (Robertson's Ruby, 1992) how Ray's mature work continued to combine a strongly anti-colonial viewpoint with a shifting perspective on Indian nationhood and an unequivocal commitment to cultural cosmopolitanism. Analysing how Ray articulated his ideological positions through the quintessentially liberal device of complexly staged debates that were apparently free, but in fact closed by the scenarist/director on ideologically specific notes, this article concludes that Ray's reputation as an all-forgiving, ‘everybody-has-his-reasons’ humanist is based on simplistic or even tendentious readings of his work

Genomic and Genic Deletions of the FOX Gene Cluster on 16q24.1 and Inactivating Mutations of FOXF1 Cause Alveolar Capillary Dysplasia and Other Malformations

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare, neonatally lethal developmental disorder of the lung with defining histologic abnormalities typically associated with multiple congenital anomalies (MCA). Using array CGH analysis, we have identified six overlapping microdeletions encompassing the FOX transcription factor gene cluster in chromosome 16q24.1q24.2 in patients with ACD/MPV and MCA. Subsequently, we have identified four different heterozygous mutations (frameshift, nonsense, and no-stop) in the candidate FOXF1 gene in unrelated patients with sporadic ACD/MPV and MCA. Custom-designed, high-resolution microarray analysis of additional ACD/MPV samples revealed one microdeletion harboring FOXF1 and two distinct microdeletions upstream of FOXF1, implicating a position effect. DNA sequence analysis revealed that in six of nine deletions, both breakpoints occurred in the portions of Alu elements showing eight to 43 base pairs of perfect microhomology, suggesting replication error Microhomology-Mediated Break-Induced Replication (MMBIR)/Fork Stalling and Template Switching (FoSTeS) as a mechanism of their formation. In contrast to the association of point mutations in FOXF1 with bowel malrotation, microdeletions of FOXF1 were associated with hypoplastic left heart syndrome and gastrointestinal atresias, probably due to haploinsufficiency for the neighboring FOXC2 and FOXL1 genes. These differences reveal the phenotypic consequences of gene alterations in cis

From Moscow with love

One of the less researched aspects of postcolonial India’s “progressive” culture is its Soviet connection. Starting in the 1950s and consolidating in the 1960s, the Union of Soviet Socialist Republics invested in building up “committed” networks amongst writers, directors, actors, and other theater- and film-practitioners across India. Thus, an entire generation of cultural professionals was initiated into the anticolonial solidarity of emerging Afro-Asian nations that were seen, and portrayed, by the Soviets as being victims of “Western” imperialism. The aspirational figure of the New Soviet Man was celebrated through the rise of a new form of “transactional sociality” (Westlund 2003). This paper looks at selected cases of cultural diplomacy—through the lens of cultural history—between the USSR and India for two decades after India’s Independence, exploring the possibility of theorizing it from the perspective of an anticolonial cultural solidarity that allowed agency to Indian interlocutors

Pathogenetics of alveolar capillary dysplasia with misalignment of pulmonary veins.

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a lethal lung developmental disorder caused by heterozygous point mutations or genomic deletion copy-number variants (CNVs) of FOXF1 or its upstream enhancer involving fetal lung-expressed long noncoding RNA genes LINC01081 and LINC01082. Using custom-designed array comparative genomic hybridization, Sanger sequencing, whole exome sequencing (WES), and bioinformatic analyses, we studied 22 new unrelated families (20 postnatal and two prenatal) with clinically diagnosed ACDMPV. We describe novel deletion CNVs at the FOXF1 locus in 13 unrelated ACDMPV patients. Together with the previously reported cases, all 31 genomic deletions in 16q24.1, pathogenic for ACDMPV, for which parental origin was determined, arose de novo with 30 of them occurring on the maternally inherited chromosome 16, strongly implicating genomic imprinting of the FOXF1 locus in human lungs. Surprisingly, we have also identified four ACDMPV families with the pathogenic variants in the FOXF1 locus that arose on paternal chromosome 16. Interestingly, a combination of the severe cardiac defects, including hypoplastic left heart, and single umbilical artery were observed only in children with deletion CNVs involving FOXF1 and its upstream enhancer. Our data demonstrate that genomic imprinting at 16q24.1 plays an important role in variable ACDMPV manifestation likely through long-range regulation of FOXF1 expression, and may be also responsible for key phenotypic features of maternal uniparental disomy 16. Moreover, in one family, WES revealed a de novo missense variant in ESRP1, potentially implicating FGF signaling in the etiology of ACDMPV

The Methodology of Modern Macroeconomics and the Descriptive Approach to Discounting

Critics of modern macroeconomics often raise concerns about unwarranted welfare conclusions and data mining. This paper illustrates these concerns with a thought experiment, based on the debate in environmental economics about the appropriate discount rate in climate change analyses: I set up an economy where a social evaluator wants to determine the optimal time path of emission levels, and seeks advice for this from an old-style neo-classical macroeconomist and a new neo-classical (modern) macroeconomist; I then describe how both economists analyze the economy, their policy advice, and their mistakes. I then use the insights from this thought experiment to point out some pitfalls of the modern macroeconomic methodology

The Structural Relationship Between Current and Capital Account Balance in India: A Time Series Analysis

The long run relationship between current account balance (CAB) and capital account balance (KAB) and the repercussions of capital account convertibility (KAC) on growth process of a country is a much debated issue. In particular, in the aftermath of the Southeast Asian crisis, the limitation of the liberal capital regime for a developing country like India is often highlighted in the literature. However, the probable impact of introducing KAC on CAB in India generally is discussed theoretically. Though some of the existing studies in India have earlier focused on this research question, they have done so by exogenously assuming the existence of a single structural break in the interrelationship between CAB and KAB. The present study intends to bridge the gap in the literature by raising two empirical questions: first, how far KAC is likely to destabilize the CAB and second, measuring the strength of the interrelationship between CAB and KAB. The current paper also contributes to the literature by incorporating multiple endogenous structural breaks in the empirical analysis. The empirical findings do not support any long term relationship between capital and current account balance and reveals that two significant structural breaks are observed in 1993-94 and 2003-04

The nature of economic development and the economic development of nature

Contemporary models of growth and development are founded on a category error: they ignore nature as a form of productive capital. Using as backdrop two recent books on the Indian economy that are representative of the prevailing orthodoxy, I review and in part extend an emerging literature that integrates development and environmental thinking. Contributors to the literature have reworked the economics of the household, communities, and other non-market institutions, reframed national accounting, reconstructed the theory of macro-economic development and public and trade policy, and revised the theory of collective action. In this paper I focus on a small part of the literature: economic evaluation. I develop the notion of sustainable development and construct a unified language for sustainability and policy analyses. I show that by economic growth we should mean growth in wealth - which is the social worth of an economy's entire set of capital assets - not growth in GDP nor the many ad hoc indicators of human development that have been proposed in recent years. The concept of wealth invites us to extend the notion of capital assets and the idea of investment well beyond conventional usage. I also show that by sustainable development we should mean development in which wealth (per head) adjusted for its distribution does not decline. This has radical implications for the way national accounts are prepared and interpreted. I then provide an account of a recent publication that has put the theory to work by studying the composition of wealth accumulation in contemporary India. Although much attention was given by the study's authors to the measurement of natural capital, due to a paucity of data the value of natural capital is acknowledged by them to be under-estimated, in all probability by a large margin. The study reveals that the entire architecture of contemporary development thinking is stacked against nature. These are still early days in the measurement of the wealth of nations, but both theory and the few empirical studies we now have at our disposal should substantially alter the way we interpret the progress and regress of nations