Superresolution without Separation

This paper provides a theoretical analysis of diffraction-limited superresolution, demonstrating that arbitrarily close point sources can be resolved in ideal situations. Precisely, we assume that the incoming signal is a linear combination of M shifted copies of a known waveform with unknown shifts and amplitudes, and one only observes a finite collection of evaluations of this signal. We characterize properties of the base waveform such that the exact translations and amplitudes can be recovered from 2M + 1 observations. This recovery is achieved by solving a a weighted version of basis pursuit over a continuous dictionary. Our methods combine classical polynomial interpolation techniques with contemporary tools from compressed sensing.Comment: 23 pages, 8 figure

Diffuse Interstellar Bands Toward HD 62542

Diffuse interstellar bands (DIBs) have been detected for the first time along the peculiar translucent line of sight toward HD 62542, which passes through a diffuse cloud core. Although only a small fraction (18 out of more than 300) of generally weak DIB features have been shown to correlate with C_2 and C_3 (the "C_2 DIBs"), it is predominantly these DIBs that are observed toward HD 62542. The typically strong DIBs λλ5780 and 5797 are detected but are significantly weaker than toward other lines of sight with similar reddening. Other commonly observed DIBs (such as λλ4430, 6270, and 6284) remain noticeably absent. These observations further support the suggestion that the line of sight toward HD 62542 crosses only the core of a diffuse cloud and show that the correlation between the C_2 DIBs and small carbon chains is maintained in environments with very large fractions of molecular hydrogen, f_(H_2) > 0.8. A comparison of CH, CN, C_2, and C_3 column densities and C_2 DIB strengths toward HD 62542, HD 204827, and HD 172028 suggests that the line of sight toward HD 204827 passes through a diffuse cloud core similar to that seen toward HD 62542, as well as what might be referred to as a diffuse cloud envelope. This indicates that the bare core toward HD 62542 may not have significantly different relative chemical abundances from other diffuse cloud cores and that the C_2 DIBs may serve as a diagnostic of such cores

Observations of Rotationally Resolved C_3 in Translucent Sight Lines

The rotationally resolved spectrum of the A^1Π_u ← X^1Σ^+_g 000-000 transition of C_3, centered at 4051.6 Å, has been observed along 10 translucent lines of sight. To interpret these spectra, a new method for the determination of column densities and analysis of excitation profiles involving the simulation and fitting of observed spectra has been developed. The populations of lower rotational levels (J ≤ 14) in C_3 are best fitted by thermal distributions that are consistent with the kinetic temperatures determined from the excitation profile of C_2. Just as in the case of C_2, higher rotational levels (J > 14) of C_3 show increased nonthermal population distributions in clouds that have been determined to have total gas densities below ~500 cm^(-3)

Why Have the Peninsular Negritos Remained Distinct?

The primary focus of this article is on the so-called negritos of Peninsular Malaysia and southern Thailand, but attention is also paid to other parts of Southeast Asia. I present a survey of current views on the negrito phenotype—is it single or many? If the phenotype is many (as now seems likely), it must have resulted from parallel evolution in the several different regions where it has been claimed to exist. This would suggest (contrary to certain views that have been expressed on the basis of very partial genetic data) that the phenotype originated recently and by biologically well-authenticated processes from within the neighboring populations. Whole-genome and physical-anthropological research currently support this view. Regardless of whether the negrito phenotype is ancient or recent - and to the extent that it retains any valid biological reality (which is worth questioning) - explanations are still needed for its continued distinctiveness. In the Malay Peninsula, a distinctive Semang societal pattern followed by most, but not all, so-called negritos may have been responsible for this by shaping familial, breeding, and demographic patterns to suit the two main modes of environmental appropriation that they have followed, probably for some millennia: nomadic foraging in the forest, and facultative dependence on exchange or labor relations with neighboring populations. The known distribution of negritos in the Malay Peninsula is limited to areas within relatively easy reach of archaeologically authenticated premodern transpeninsular trading and portage routes, as well as of other non-negrito, Aslian-speaking populations engaged in swidden farming. This suggests that their continued distinctiveness has resulted from a wish to maintain a complementary advantage vis-à-vis other, less specialized populations. Nevertheless, a significant degree of discordance exists between the associated linguistic, societal-tradition, and biological patterns which suggests that other factors have also been at play

The multifunctional NS1 protein of influenza A viruses

The non-structural (NS1) protein of influenza A viruses is a non-essential virulence factor that has multiple accessory functions during viral infection. In recent years, the major role ascribed to NS1 has been its inhibition of host immune responses, especially the limitation of both interferon (IFN) production and the antiviral effects of IFN-induced proteins, such as dsRNA-dependent protein kinase R (PKR) and 2'5'-oligoadenylate synthetase (OAS)/RNase L. However, it is clear that NS1 also acts directly to modulate other important aspects of the virus replication cycle, including viral RNA replication, viral protein synthesis, and general host-cell physiology. Here, we review the current literature on this remarkably multifunctional viral protein. In the first part of this article, we summarize the basic biochemistry of NS1, in particular its synthesis, structure, and intracellular localization. We then discuss the various roles NS1 has in regulating viral replication mechanisms, host innate/adaptive immune responses, and cellular signalling pathways. We focus on the NS1-RNA and NS1-protein interactions that are fundamental to these processes, and highlight apparent strain-specific ways in which different NS1 proteins may act. In this regard, the contributions of certain NS1 functions to the pathogenicity of human and animal influenza A viruses are also discussed. Finally, we outline practical applications that future studies on NS1 may lead to, including the rational design and manufacture of influenza vaccines, the development of novel antiviral drugs, and the use of oncolytic influenza A viruses as potential anti-cancer agents.Publisher PDFPeer reviewe

Religious Identity and Economic Behavior

We randomly vary religious identity salience in laboratory subjects to test how identity salience contributes to six hypothesized links from prior literature between religious identity and economic behavior. We find that religious identity salience makes Protestants increase contributions to public goods. Catholics decrease contributions to public goods, expect others to contribute less to public goods, and become less risk averse. Jews more strongly reciprocate as an employee in a bilateral labor market gift-exchange game. We find no evidence of religious identity salience effects on disutility of work effort, discount rates, or generosity in a dictator game.

Switches and mortar in the Internet's shadow : a study of the effects of technology on competitive strategy for the Internet's landlords

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2000.Includes bibliographical references (leaves 132-138).Communications technology has experienced a period of explosive growth, driven by a confluence of legal, political and technical factors including the following: the 1968 Carter Phone and 1980's competitive carrier decisions, the 1984 divestiture of AT&T, the Telecommunications Act of 1996, the development and standardization of new technologies, and the proliferation of the Internet and World Wide Web. This thesis asks the fundamental questions: How has the rapid growth of the Internet and other communications technologies changed the competitive strategy of commercial tenants, and how have these changes affected commercial real estate developers? This study proposes that developers and landlords need to use more forward-looking theories of competitive strategy in order to understand the current and future real estate needs of technology-driven commercial tenants. Telecommunications deregulation and the growth of the Internet led to the creation of a new and rapidly growing high technology industry and commercial tenancy. Deregulation and the Internet also transformed the way traditional commercial real estate uses information technology, encouraged the forging of partnerships between commercial real estate professionals and "last mile" information technology contractors, and resulted in the creation of a new commercial real estate product-the telecom hotel.' Current literature suggests traditional commercial tenants might differ from Internet-based business tenants in four general areas of the development process: feasibility, site selection, design and building operations. The proliferation of the Internet as a catalyst for new real estate products, commercial tenants and partnerships, and the observed differences in development practices between traditional and commercial tenants are both clues to fundamental differences between these two tenants' competitive strategies. It is possible to understand these clues to tenant behavior by taking an in-depth look at how these two tenants compete in their respective industries. Traditional commercial business tenants appear to conform to Michael Porter's theories on competitive strategy and advantage. High-tech tenant's competitive strategies seem to be more accurately reflected by Gary Hamel and C.K. Prahalad's model of competition for the future. These two theories, and the industries they represent, differ in four dimensions: Future versus Past/Present orientation, technology use, rate of growth, and resource use. In comparing three case studies on these four strategic dimensions, this thesis concludes that Porter's more stable, efficiency-oriented model does explain the strategy of Northwestern Mutual, a large insurance organization. Hamel and Prahalad's model better explains the hectic, high growth, future orientation of Akamai and YankeeTek Incubator as well as Teleplace, a telecom hotel service company. Hamel and Prahalad and Porter's frameworks explain significant discrepancies between predicted development practices based on current industry thinking, and observed development practices based on these in depth case studies. This thesis thus verifies a need by real estate developers and landlords to use forward-looking theories of competitive strategy when examining the current and future needs of hightech tenants.by Geoffrey Morgan and Benjamin V.A. Pettigrew.S.M