cssi/SciSciGPT-SciSciNet huggingface dataset:
Market Power in the Carbonated Soft Drink Industry

AbstractWe investigate the strategic pricing for leading brands sold in the carbonated softdrink (CSD) market in the context of a ⁄exible demand speci–cation (i.e. randomparameter nested logit) and a structural pricing equation. Our approach does not relyupon the often used ad hoc linear approximations to demand and pro–t-maximizing–rst-order conditions. We estimate the structural pricing equation using four di⁄erentestimators (i.e. OLS, LIML, 2SLS, and GMM) and compare the implied deviationfrom Bertrand-Nash competition. Our results suggest that retailers, on average, priceCSD brands below their cost, likely a result of the competitive retailing environment.We also –nd CSD wholesalers price their brands signi–cantly more cooperatively thanBertrand-Nash would suggest, thus in⁄ating pro–ts. 1 Introduction The rich content of scanner data enables the estimation of structural econometric modelsto be used to investigate market power and analyze policy. Recent advances in structuralapproaches to empirical market power analysis combines estimated demand functions withgame-theoretic models of a particular industry to estimate its competitive nature. However,economic and econometric theory are often silent on the speci–c econometric estimators thatshould be employed. Each one having similar, but di⁄ering restrictions on the assumptionsof the underlying sample from which the data is collected. As a result, the objective ofthis study is to empirically compare several di⁄erent estimators of a supply model, and lookat the di⁄erences each one implies with respect to the nature of the competitive game thecarbonated soft drink (CSD) market plays.The CSD category is used in our empirical analysis for several reasons. First, the in-dustry is highly concentrated at the manufacturing level, being largely dominated by twomanufacturers. However, retail outlets have recently been introducing, and pushing, theirown private label brands as a way of expanding category pro–ts. Second, the industry iswell known among a wide range of consumers not only in the U.S., but largely throughoutthe world. Thus many retail outlets carry the same set of products making the competitivenature of the CSD industry an empirical question at not only the manufacturer level, butalso at the retail level. Finally, given the long history of the industry, particularly in theU.S., a steady state equilibrium is likely to exist. Thus the CSD market is an ideal categoryfor comparing the competitive nature implied from several di⁄erent econometric estimators.The remainder of the paper is organized as follows. In the next section we present theeconometric model used to analyze the market power of the CSD market. This section beginswith a brief overview of the demand and supply models used, followed by their speci–cation.1
Agony and ecstasy: teaching a computationally intensive introductory statistics course using Stata

In the last decade, a sea change has occurred in the organization of introductory statistics courses. The mantra of "more data, less lecture" is widely repeated while active learning opportunities receive increasing focus. At Smith College, a small liberal arts college, a number of introductory statistics courses are offered, with varying mathematical prerequisites. Stata is used as the computing environment for many of these courses. In all courses, students engage in the analysis of real-world example datasets, often taught in the form of mini case studies (using a set of lab materials developed at UCLA). For the more mathematically savvy students, introductory statistics concepts are introduced through simulation and other activities. While Stata serves as an easy to use environment for statistical analysis, there are areas where additional functionality would improve its use as a testbed for statistical investigation. In this talk, I will review the use of Stata for both of these purposes, and detail areas of strengths and potential improvements.
Minimum weight perfect matching of fault-tolerant topological quantum error correction in average O(1) parallel time

Consider a 2-D square array of qubits of extent L × L. We provide a proof that the minimum weight perfect matching problem associated with running a particular class of topological quantum error correction codes on this array can be exactly solved with a 2-D square array of classical computing devices, each of which is nominally associated with a fixed number N of qubits, in constant average time per round of error detection independent of L provided physical error rates are below fixed nonzero values, and other physically reasonable assumptions. This proof is applicable to the fully fault-tolerant case only, not the case of perfect stabilizer measurements.
Pork Production Contracts and Food Safety Issues

Introduction The pork production industry has been moving toward coordinated efforts where there is an increased linkage between industry participants ranging from input suppliers, to producers, to packers/processors, and the retail or consumer level. Contracts have been used as one of the mechanisms to link the participants. These contracts vary widely, covering such items as production standards or technology that may have food safety associations, inputs to be used in production, market timing, and payments and payment methods, etc. By linking industry participants, hog purchase/production contracts have been used to develop improved organization and flow of products, enhance industry movement toward improved food safety through reduced residues and/or pathogens, develop more uniform products, and spur the movement toward production of leaner pork. In the movement toward leaner pork, the industry has rapidly moved to carcass pricing and lean premiums rather than pricing of the live hog.
Robust Standard Errors in Small Samples: Some Practical Advice

Abstract We study the properties of heteroskedasticity-robust confidence intervals for regression parameters. We show that confidence intervals based on a degrees-of-freedom correction suggested by Bell and McCaffrey (2002) are a natural extension of a principled approach to the Behrens-Fisher problem. We suggest a further improvement for the case with clustering. We show that these standard errors can lead to substantial improvements in coverage rates even for samples with fifty or more clusters.We recommend that researchers routinely calculate the Bell-McCaffrey degrees-of-freedom adjustment to assess potential problems with conventional robust standard errors.
HIV and Fertility Revisited

Abstract Young (2005) argues that HIV related population declines reinforced by the fertility response to the epidemic will lead to higher capital–labor ratios and to higher per capita incomes in the affected countries of Africa. Using household level data on fertility from South Africa and relying on between cohort variations in country level HIV infection, he estimates a large negative effect of HIV prevalence on fertility. However, the studies that utilize the recent rounds of Demographic Health Surveys, where fertility outcomes are linked to HIV status based on testing, find no effect of the disease on the fertility behavior. This paper tries to bridge this gap by revisiting Young's findings. Young (2005) includes data before 1990, when no data are available on HIV prevalence rates. He assigns all the fertility observations before 1990 with HIV prevalence rates of zero, and this appears to drive the significant negative effect found in his study. When one restricts the sample to the period 1990–1998, where actual HIV data are available, the effect of HIV prevalence on fertility turns out to be positive for South Africa. Simulating Young's model utilizing these new estimates shows that the future generations of South Africa are worse off.
The Liquidity Premium of Near-Money Assets

This article examines the link between the opportunity cost of money and time-varying liquidity premia of near-money assets. Higher interest rates imply higher opportunity costs of holding money and hence a higher premium for the liquidity service benefits of assets that are close substitutes for money. Consistent with this theory, short-term interest rates in the United States, United Kingdom, and Canada have a strong positive relationship with the liquidity premium of Treasury bills and other near-money assets over periods going back to the 1920s. Once the opportunity cost of money is taken into account, Treasury security supply variables lose their explanatory power for the liquidity premium, except for transitory short-run effects. These findings indicate a high elasticity of substitution between money and near-money assets. As a consequence, a central bank that follows an interest rate operating target not only elastically accommodates and neutralizes shocks to money demand, but effectively also shocks to near-money asset supply and demand.
Determining the Rationality of Marketing Strategy on Farms

The focus of farm management, as a discipline, has reflected historically the assumption that farms are embedded in near-perfectly competitive market structures. The common validity of this assumption is plain. As open systems, farms have asymmetric relationships with their environment: they are significantly more influenced by it than influencing it. However, farmers seem often not to appreciate the implications of this for their management options. Nor, arguably, is the farm management discipline yet well equipped to analyse initiatives that farmers might contemplate to enhance their control over market outcomes, specifically, as a means of exerting greater control over business performance. In this paper a framework for the analysis of the prospects for product differentiation of farm output is presented in an attempt to fill this lacuna. Introduction As an academic discipline, historically farm management (FM) has been focused on management decision making (Charry and Parton 2002). The domain of physical agricultural production activities may have been taught within farm management qualifications, but the discipline has persistently involved analysis for decisions. Within it farms are characterised as purposeful, open, complex systems having to cope with substantial stochasticity (Dillon 1992). Economics has been the discipline used to most effect to analyse farm management decisions (Malcolm 2004).
Birth Weight in the Long Run

We study the effect of birth weight on long-run outcomes using data on Swedish twins born between 1926 and 1958 linked to administrative records spanning entire life-time labor market histories. We ...
Electron energization and transport in the magnetotail during substorms

It has been suggested recently that electrons are accelerated both near the reconnection site and during subsequent earthward transport. We provide global and quantitative evidence for this two-step process by examining electron energization during a substorm event that occurred on 11 March 2008, when the Earth's magnetosphere was immersed in southward interplanetary magnetic field and high-speed solar wind. The approach is to integrate coordinated measurements by Time History of Events and Macroscale Interactions during Substorms (THEMIS), global magnetohydrodynamic (MHD) modeling of the magnetosphere driven by upstream solar wind conditions, and large-scale kinetics (LSK) simulation. In this event, THEMIS P2 at XGSM ~ − 15 RE detected a dipolarization pulse-like magnetic structure coupled with energetic electron flux increase. About 1 min later, P3 and P4 at XGSM ~ − 10 RE observed dipolarized magnetic field and even larger flux increase. These multipoint data are applied to benchmark the MHD/LSK simulation. We quantify electron energization near the reconnection site and during earthward transport. We show that electrons were initially energized near the reconnection site, and subsequently further adiabatically accelerated far away from the reconnection site as the dipolarization front formed and grew. The adiabatic enhancement was rather effective given steep source electron distribution as a function of energy. In the outer magnetosphere with strong flows, E × B drift statistically dominated electron guiding center motion; thus, electrons were transported along the flow channel with small spatial diffusion. Close to the Earth, gradient and curvature drifts became appreciable; therefore, electrons circled around the region of large magnetic field.
Weathering of phosphorus in black shales

[1] Rock weathering is the ultimate source of phosphorus (P) to the oceans, where P can be a limiting nutrient for biological production. In this paper, P weathering is examined in soil chronosequences formed in weathering profiles on the organic-rich Woodford Shale, New Albany Shale and Green River Shale. At all sites, organic P and inorganic P concentrations reveal that P weathering is far from complete, prior to erosion. Carbon (C)/P ratios decrease significantly from unweathered shale to the weathered shale at all sites, which is driven by loss of total organic C with weathering. Here we characterize organic phosphorus across a weathering profile from the Woodford Shale using solid-state CPMAS 31P NMR spectroscopy techniques, revealing that P esters are the dominant forms of P during all stages of weathering. Certain P esters appear to be resistant to chemical weathering during the millions of years between deposition, uplift and erosion, possibly representing a significant long-term global sink for P.
Back-reaction beyond the mean field approximation

A method for solving an initial value problem of a closed system consisting of an electromagnetic mean field and its quantum fluctuations coupled to fermions is presented. By tailoring the large N f expansion method to the Schwinger-Keldysh closed time path (CTP) formulation of the quantum effective action, causality of the resulting equations of motion is ensured, and a systematic energy conserving and gauge invariant expansion about the electromagnetic mean field in powers of 1/N f is developed. The resulting equations may be used to study the quantum non- equilibrium effects of pair creation in strong electric fields and the scattering and transport processes of a relativistic e+e- plasma. Using the Bjorken ansatz of boost invariance initial conditions in which the initial electric mean field depends on the proper time only, we show numerical results for the case in which the N f expansion is truncated in the lowest order, and compare them with those of a phenomenological transport equation.
PHOTOVOLTAIC SYSTEM RESEARCH STATUS

After a decade of photovoltaic system research, most system related issues have been successfully resolved. Current system research activities are now oriented toward maintaining and updating the comprehensive database on system performance established by previous research efforts, integrating new components into system designs, and transferring the accumulated information to industry and users of the technology. This paper presents a brief overview of the status of system research in the United States, emphasizing three key activities - field evaluation, balance-of-system hardware development, and technology transfer. 5 refs., 2 tabs.
Neogene changes in Southern Ocean sedimentation based on mass accumulation rates at four continental margins

[1] High-resolution mass accumulation rates (MAR) were determined from lithologic logs based on downhole log and continuous core data for six sites at four continental margins around the Southern Ocean. Total MAR was calculated at Ocean Drilling Program (ODP) Site 1095 on the margin of the Antarctic Peninsula and ODP Site 1165 on the margin of Prydz Bay, Antarctica. Carbonate and noncarbonate (terrigenous) MAR were calculated for ODP Sites 1123 and 1124 east of New Zealand and Sites 1168 and 1172 west and southeast of Tasmania. Shifts in carbonate MAR are seen around Tasmania and New Zealand at 23 and 14 Ma, suggesting changes in deep water circulation and surface carbonate productivity at these times. Carbonate MAR dropped at Sites 1124 and 1168 at 23 Ma and increased at 14 Ma at Sites 1123, 1168, and 1172. The overall character of total MAR at Antarctic Sites 1095 and 1165 is a continual and relatively constant decrease in total MAR during the Neogene, with periods of stepwise decrease. One such decrease is seen at 14 Ma at Site 1165, coincident with increased carbonate MAR in New Zealand and Tasmania (Sites 1123, 1124, 1168 and 1172) and likely related to mid-Miocene expansion of the East Antarctic Ice Sheet. Another step drop in total MAR is seen at ∼9 Ma at Site 1165, possibly reflecting diversion of sediment to a newly formed Prydz Channel fan.
Equiangular spherical codes in quantum cryptography

Quantum key distribution protocols based on equiangular spherical codes are introducedand their behavior under the intercept/resend attack investigated. Such protocols offera greater range of secure noise tolerance and speed options than protocols based ontheir cousins, the mutually-unbiased bases, while also enabling the determination of thechannel noise rate without the need to sacrifice key bits. For fixed number of signalstates in a given dimension, the spherical code protocols offer Alice and Bob more noisetolerance at the price of slower key generation rates.
A hereditarily indecomposable tree-like continuum without the fixed point property

A hereditarily indecomposable tree-like continuum without the fixed point property is constructed. The example answers a question of Knaster and Bellamy.
Stability analysis of active clock deskewing systems using a control theoretic approach

In this paper, a methodology for analyzing closed loop clock distribution and active deskewing networks is proposed. An active clock distribution and deskewing network is modelled as a closed loop feedback control system using state space equations. The state space models of the system were then used to simulate the clock deskewing scheme, and most importantly, to analyze the stability using the integral quadratic constraints method. Such a systematic analysis method can be very useful to designers as they would be able to determine how the deskewing network behaves, thus, avoiding repeated simulations. The proposed approach can be further extended to determine performance of such systems under different configurations. We show how the proposed method is applied to an experimental clock deskewing system for performance and stability analysis.
Health-care service utilization in substance abusers receiving contingency management and standard care treatments.

Aim To determine the impact of standard care and contingency management treatments on the utilization of general healthcare services by substance abusers.
Independent effects of temperature and precipitation on modeled runoff in the conterminous United States

[1] A water-balance model is used to simulate time series of water-year runoff for 4 km × 4 km grid cells for the conterminous United States during the 1900–2008 period. Model outputs are used to examine the separate effects of precipitation and temperature on runoff variability. Overall, water-year runoff has increased in the conterminous United States and precipitation has accounted for almost all of the variability in water-year runoff during the past century. In contrast, temperature effects on runoff have been small for most locations in the United States even during periods when temperatures for most of the United States increased significantly.
Does privacy require true randomness

Most cryptographic primitives require randomness (for example, to generate their secret keys). Usually, one assumes that perfect randomness is available, but, conceivably, such primitives might be built under weaker, more realistic assumptions. This is known to be true for many authentication applications, when entropy alone is typically sufficient. In contrast, all known techniques for achieving privacy seem to fundamentally require (nearly) perfect randomness. We ask the question whether this is just a coincidence, or, perhaps, privacy inherently requires true randomness? We completely resolve this question for the case of (information-theoretic) private-key encryption, where parties wish to encrypt a b-bit value using a shared secret key sampled from some imperfect source of randomness S. Our main result shows that if such n-bit source S allows for a secure encryption of b bits, where b > log n, then one can deterministically extract nearly b almost perfect random bits from S. Further, the restriction that b > log n is nearly tight: there exist sources S allowing one to perfectly encrypt (log n - loglog n) bits, but not to deterministically extract even a single slightly unbiased bit. Hence, to a large extent, true randomness is inherent for encryption: either the key length must be exponential in the message length b, or one can deterministically extract nearly b almost unbiased random bits from the key. In particular, the one-time pad scheme is essentially "universal". Our technique also extends to related computational primitives which are perfectly-binding, such as perfectly-binding commitment and computationally secure private- or public-key encryption, showing the necessity to efficiently extract almost b pseudorandom bits.
Epigenetics of gene expression in human hepatoma cells: expression profiling the response to inhibition of DNA methylation and histone deacetylation.

Background DNA methylation and histone deacetylation are epigenetic mechanisms that play major roles in eukaryotic gene regulation. We hypothesize that many genes in the human hepatoma cell line HepG2 are regulated by DNA methylation and histone deacetylation. Treatment with 5-aza-2'-deoxycytidine (5-aza-dC) to inhibit DNA methylation with and/or Trichostatin A (TSA) to inhibit histone deacetylation should allow us to identify genes that are regulated epigenetically in hepatoma cells.
Syntheses, Structural Characterization, and Catalytic Properties of Di- and Trinickel Polyoxometalates

The syntheses, structural characterization, and catalytic properties of two different nickel-containing polyoxometalates (POMs) are presented. The dinickel-containing sandwich-type POM [Ni2(P2W15O56)2](20-) (Ni2) exhibits an unusual αααα geometry. The trinickel-containing Wells-Dawson POM [Ni3(OH)3(H2O)3P2W16O59](9-) (Ni3) shows a unique structure where the [α-P2W15O56](12-) ligand is capped by a triangular Ni3O13 unit and a WO6 octahedron. Ni3 shows a high catalytic activity for visible-light-driven hydrogen evolution, while the activity for Ni2 is minimal. An analysis of the structures of multinickel-containing POMs and their hydrogen evolution activity is given.
Modding as an Open Source Approach to Extending Computer Game Systems

This paper examines what is known so far about the role of open source software development within the world of game mods and modding practices. Game modding has become a leading method for developing games by customizing or creating OSS extensions to game software in general, and to proprietary closed source software games in particular. What, why, and how OSS and CSS come together within an application system is the subject for this study. The research method is observational and qualitative, so as to highlight current practices and issues that can be associated with software engineering and game studies foundations. Numerous examples of different game mods and modding practices are identified throughout.
Assessing the Impacts of Non-Ricardian Households in an Estimated New Keynesian DSGE Model

A New Keynesian DSGE model with non-Ricardian households is estimated for the Portuguese economy and the stability of the model’s prediction (posterior distributions, impulse responses, and sources of fluctuations in endogenous variables) tested under different assumptions on non-Ricardian households. Their share is estimated to be relatively high (58 %). Furthermore, estimates of several parameters as well as the magnitude and persistence of shocks are particularly sensitive to the share of non-Ricardian households. Impulse responses to consumption preference and productivity shocks are amplified for lower shares; for greater proportions, the model predicts more noticeable responses to price markup and government spending shocks. Fluctuations in output growth are mainly driven by productivity shocks for a lower share and by price markup shocks in the opposite scenario. A high proportion of these households together with a high degree of price stickiness lead the Taylor-type interest rate rule solution to be locally indeterminate.
Dynamic Programming via Static Incrementalization

Dynamic programming is an important algorithm design technique. It is used for solving problems whose solutions involve recursively solving subproblems that share subsubproblems. While a straightforward recursive program solves common subsubproblems repeatedly and often takes exponential time, a dynamic programming algorithm solves every subsubproblem just once, saves the result, reuses it when the subsubproblem is encountered again, and takes polynomial time. This paper describes a systematic method for transforming programs written as straightforward recursions into programs that use dynamic programming. The method extends the original program to cache all possibly computed values, incrementalizes the extended program with respect to an input increment to use and maintain all cached results, prunes out cached results that are not used in the incremental computation, and uses the resulting incremental program to form an optimized new program. Incrementalization statically exploits semantics of both control structures and data structures and maintains as invariants equalities characterizing cached results. The principle underlying incrementalization is general for achieving drastic program speedups. Compared with previous methods that perform memoization or tabulation, the method based on incrementalization is more powerful and systematic. It has been implemented and applied to numerous problems and succeeded on all of them.
A New Measure of College Quality to Study the Effects of College Sector and Peers on Degree Attainment

Abstract Students starting at a two-year college are much less likely to graduate than similar students who start at a four-year college, but the sources of this attainment gap are largely unexplained. This paper investigates the attainment consequences of sector choice and peer quality among recent high school graduates. Using data on all Preliminary SAT (PSAT) test-takers between 2004 and 2006, we develop a novel measure of peer ability for most two-year and four-year colleges in the United States—the average PSAT of enrolled students. We document substantial variation in this measure of peer quality across two-year colleges and nontrivial overlap between the two-year and four-year sectors. We find that half the gap in bachelor's degree attainment rates across sectors is explained by differences in peers, leaving room for structural barriers to transferring between institutions to also play an important role.
Hierarchical heavy hitters with the space saving algorithm

The Hierarchical Heavy Hitters problem extends the notion of frequent items to data arranged in a hierarchy. This problem has applications to network traffic monitoring, anomaly detection, and DDoS detection. We present a new streaming approximation algorithm for computing Hierarchical Heavy Hitters that has several advantages over previous algorithms. It improves on the worst-case time and space bounds of earlier algorithms, is conceptually simple and substantially easier to implement, offers improved accuracy guarantees, is easily adopted to a distributed or parallel setting, and can be efficiently implemented in commodity hardware such as ternary content addressable memory (TCAMs). We present experimental results showing that for parameters of primary practical interest, our two-dimensional algorithm is superior to existing algorithms in terms of speed and accuracy, and competitive in terms of space, while our one-dimensional algorithm is also superior in terms of speed and accuracy for a more limited range of parameters.
On Modal Logics of Partial Recursive Functions

The classical propositional logic is known to be sound and complete with respect to the set semantics that interprets connectives as set operations. The paper extends propositional language by a new binary modality that corresponds to partial recursive function type constructor under the above interpretation. The cases of deterministic and non-deterministic functions are considered and for both of them semantically complete modal logics are described and decidability of these logics is established.
Dominating sets in triangulations on surfaces

A dominating set D ⊆ V ( G ) of a graph G is a set such that each vertex v ∈ V ( G ) is either in the set or adjacent to a vertex in the set. Matheson and Tarjan (1996) proved that any n -vertex plane triangulation has a dominating set of size at most n /3, and conjectured a bound of n /4 for n sufficiently large. King and Pelsmajer recently proved this for graphs with maximum degree at most 6. Plummer and Zha (2009) and Honjo, Kawarabayashi, and Nakamoto (2009) extended the n /3 bound to triangulations on surfaces. We prove two related results: (i) There is a constant c 1 such that any n -vertex plane triangulation with maximum degree at most 6 has a dominating set of size at most n /6 + c 1 . (ii) For any surface S , t ≥ 0, and e > 0, there exists c 2 such that for any n -vertex triangulation on S with at most t vertices of degree other than 6, there is a dominating set of size at most n (1/6 + e ) + c 2 . As part of the proof, we also show that any n -vertex triangulation of a non-orientable surface has a non-contractible cycle of length at most 2√ n . Albertson and Hutchinson (1986) proved that for n -vertex triangulation of an orientable surface other than a sphere has a non-contractible cycle of length √(2 n ), but no similar result was known for non-orientable surfaces.
Developing country trade policies and market access issues : 1990-2012

The study presents a comprehensive review of developing country trade policies and market access issues as they evolved over the period 1990-2012. The main findings are, first, that applied tariffs as well as traditional core non-tariff measures have declined significantly over time in both developed and developing countries. Second, the instruments of protection used by developed and developing countries are becoming increasingly similar: trade remedies, especially anti-dumping are the instruments of choice for all except low-income developing countries. Third, agriculture is the main sector where developing countries face access problems in OECD markets. Fourth, regional and other preferential trade agreements are both a result and a cause of the lack of progress in multilateral trade negotiations. They violate the basic World Trade Organization tenet of most favored nation and thus pose a potential threat to the multilateral system and a potential stimulus to further multilateral collaboration. Fifth, sanitary and phytosanitary and technical barriers to trade are being increasingly used by both developed and developing countries but their protective intent is difficult to gauge. There is a need for increased vigilance, transparency, and reporting to ensure that they are not being used as a means of protection of economic interests. Sixth, the service sectors are the most promising area where efforts for further liberalization are needed and may produce significant benefits. And seventh, far less additional protection has been put in place following the 2008 financial crisis compared with what had been feared or what had happened in earlier crises.
X-ray flares, plateaus and chromatic breaks of GRB afterglows from up-scattered forward-shock emission

Scattering of the forward-shock synchrotron emission by a relativistic outflow located behind the leading blast wave may produce an X-ray emission brighter than that coming directly from the forward shock and may explain four features displayed by Swift X-ray afterglows: flares, plateaus (slow decays), chromatic light-curve breaks and fast post-plateau decays. For a cold scattering outflow, the reflected flux overshines the primary one if the scattering outflow is nearly baryon-free and highly relativistic. These two requirements can be relaxed if the scattering outflow is energized by weak internal shocks, so that the incident forward-shock photons are also inverse-Compton scattered, in addition to bulk scattering. Sweeping-up of the photons left behind by the forward shock naturally yields short X-ray flares. Owing to the boost in photon energy produced by bulk scattering, the reflected emission is more likely to overshine that coming directly from the forward shock at higher photon energies, yielding light-curve plateaus and breaks that appear only in the X-ray. The brightness, shape and decay of the X-ray light-curve plateau depend on the radial distribution of the scatterer's Lorentz factor and mass flux. Chromatic X-ray light-curve breaks and sharp post-plateau decays cannot be accommodated by the direct forward-shock emission and argue in favour of the scattering-outflow model proposed here. On the other hand, the X-ray afterglows without plateaus, those with achromatic breaks and those with very long lived power-law decays are more naturally accommodated by the standard forward-shock model. Thus, the diversity of X-ray light curves arises from the interplay of the scattered and direct forward-shock emissions.
Block sensitivity of minterm-transitive functions

Boolean functions with a high degree of symmetry are interesting from a complexity theory perspective: extensive research has shown that these functions, if nonconstant, must have high complexity according to various measures. In a recent work of this type, Sun (2007) [9] gave lower bounds on the block sensitivity of nonconstant Boolean functions invariant under a transitive permutation group. Sun showed that all such functions satisfy bs(f)[email protected](N^1^/^3). He also showed that there exists such a function for which bs(f)=O(N^3^/^7lnN). His example belongs to a subclass of transitively invariant functions called ''minterm-transitive'' functions, defined by Chakraborty (2005) [3]. We extend these results in two ways. First, we show that nonconstant minterm-transitive functions satisfy bs(f)[email protected](N^3^/^7). Thus, Sun's example has nearly minimal block sensitivity for this subclass. Second, we improve Sun's example: we exhibit a minterm-transitive function for which bs(f)=O(N^3^/^7ln^1^/^7N).
Fractional Power Series and Pairings on Drinfeld Modules

Let C be an algebraically closed field containing Fq which is com- plete with respect to an absolute value | |. We prove that under suitable constraints on the coefficients, the series f(z) = ∑ n∈Z anz q converges to a surjective, open, continuous Fq-linear homomorphism C → C whose kernel is locally compact. We characterize the locally compact sub-Fq-vector spaces G of C which occur as kernels of such series, and describe the extent to which G determines the series. We develop a theory of Newton polygons for these series which lets us compute the Haar measure of the set of zeros of f of a given valuation, given the valuations of the coefficients. The “adjoint” series f∗(z) = ∑ n∈Z a 1/qn n z1/q n converges everywhere if and only if f does, and in this case there is a natural bilinear pairing ker f × ker f∗ → Fq which exhibits ker f∗ as the Pontryagin dual of ker f . Many of these results ex- tend to non-linear fractional power series. We apply these results to construct a Drinfeld module analogue of the Weil pairing, and to describe the topological module structure of the kernel of the adjoint exponential of a Drinfeld module. Mathematical Sciences Research Institute, Berkeley, California 94720-5070 E-mail address: poonen@msri.org Current address: Department of Mathematics, Princeton University, Princeton, New Jersey 08544-1000 E-mail address: poonen@math.princeton.edu License or copyright restrictions may apply to redistribution; see http://www.ams.org/journal-terms-of-use
Neutrosophic Logic - A Generalization of the Intuitionistic Fuzzy Logic

In this paper one generalizes the intuitionistic fuzzy logic (IFL) and other logics to neutrosophic logic (NL). The differences between IFL and NL (and the corresponding intuitionistic fuzzy set and neutrosophic set) are pointed out.
Physiological studies of tryptophan transport and tryptophanase operon induction in Escherichia coli.

Escherichia coli forms three permeases that can transport the amino acid tryptophan: Mtr, AroP, and TnaB. The structural genes for these permeases reside in separate operons that are subject to different mechanisms of regulation. We have exploited the fact that the tryptophanase (tna) operon is induced by tryptophan to infer how tryptophan transport is influenced by the growth medium and by mutations that inactivate each of the permease proteins. In an acid-hydrolyzed casein medium, high levels of tryptophan are ordinarily required to obtain maximum tna operon induction. High levels are necessary because much of the added tryptophan is degraded by tryptophanase. An alternate inducer that is poorly cleaved by tryptophanase, 1-methyltryptophan, induces efficiently at low concentrations in both tna+ strains and tna mutants. In an acid-hydrolyzed casein medium, the TnaB permease is most critical for tryptophan uptake; i.e., only mutations in tnaB reduce tryptophanase induction. However, when 1-methyltryptophan replaces tryptophan as the inducer in this medium, mutations in both mtr and tnaB are required to prevent maximum induction. In this medium, AroP does not contribute to tryptophan uptake. However, in a medium lacking phenylalanine and tyrosine the AroP permease is active in tryptophan transport; under these conditions it is necessary to inactivate the three permeases to eliminate tna operon induction. The Mtr permease is principally responsible for transporting indole, the degradation product of tryptophan produced by tryptophanase action. The TnaB permease is essential for growth on tryptophan as the sole carbon source. When cells with high levels of tryptophanase are transferred to tryptophan-free growth medium, the expression of the tryptophan (trp) operon is elevated. This observation suggests that the tryptophanase present in these cells degrades some of the synthesized tryptophan, thereby creating a mild tryptophan deficiency. Our studies assign roles to the three permeases in tryptophan transport under different physiological conditions. Images
Stochastic trends and jumps in EMS exchange rates

Abstract In this paper we study the statistical properties of EMS exchange rate returns. Our findings show that jumps, time-varying parameters and conditional leptokurtosis are pertinent features in the empirical distributions of EMS exchange rate returns. Allowance for fat tails, however, tends to reduce the measured frequency of jumps in the distributions to more realistic proportions. Most successful in capturing the relevant features of EMS exchange rate returns is a combined jump-GARCH model with conditionally t-distributed innovations. (JEL F31).
Evolution of the Office on Wheels Toward the Intelligent Vehicle/Highway System

The introduction of communications through mobile cellular provided considerable productivity increases to the vehicle operator. Primitive forms of service have already been introduced and technology exists to implement a full range of office features. An intelligent vehicle/highway program is also dependent on mobile communications. Degrading traffic conditions has fueled public interest. Progress in both of these areas is dependent on cultural change, correct implementation, rate structures and infrastructure development. Many business opportunities in the communication, data base and travel service industries are being created by these developments.
International Spillovers from U.S. Fiscal Policy Shocks

I estimate the effect of U.S. government spending and tax shocks on Canada and the U.K. from 1975 to 2014, and on Japan from 1979 to 2014. Spending and tax shocks are identified using sign restrictions on the impulse responses from a vector autoregression (VAR). I find that spillover effects of expansionary fiscal shocks are not uniform across countries, though for all three countries they result in economically significant GDP increases in the short run. In addition, government spending shocks have larger effects than net tax shocks. Altogether, the results support the idea that some countries may benefit significantly from expansionary U.S. fiscal policy.
Whose Preferences Are Revealed in Hours of Work

It has become orthodox in economics research to interpret the association between hourly earnings and working hours as the expression of the preferences of workers. This convention originated in H. Gregg Lewis' explanation for the decline in hours of work since the nineteenth century. His explanation rested on an explicit resolution of the identification problem inherent in any quantity (hours)–price (wage) relation. For over 40 years, researchers have neglected this identification problem with the result that the findings in the purported “labor supply” literature are of questionable value. (JEL J22, J23, C13)
Reforming government debt markets in MENA

This paper examines the current stage of development of government securities markets in the non-GCC MENA region focusing in five countries that have government bond markets with a minimum size and greater potential for market development: Egypt, Jordan, Lebanon, Morocco and Tunisia. The analysis focuses on the five key building blocks that normally sustain deep and liquid public debt markets: (i) money markets; (ii) primary market (issuance policy and placement mechanisms); (iii) secondary market organization; (iv) investor base; and (v) clearing and settlement infrastructure. The study shows that despite country differences, several common weaknesses in the key building blocks explain the underdevelopment of MENA bond markets. Most important among these are a symbiotic relationship between banks and Governments caused by lack of alternative investments that makes banks act as captive demand and dominate bond markets, opportunistic primary issuance practices, and excess liquidity in the financial system. These demand and supply characteristics have led to highly concentrated buy-and-hold portfolios by banks and State-owned institutions, poor price discovery and lack of liquidity in secondary markets. A set of actions to unlock market development in MENA is proposed involving measures in all key building blocks - from improvements in monetary policy implementation and liquidity management to enhancements in issuance practices, price transparency, and clearing & settlement infrastructure. Measures to improve the role of mutual funds and foster foreign investor presence are also of utmost importance to increase competition and investor diversification in these markets.
Lower bounds on inequality of opportunity and measurement error

When measuring inequality of opportunity, researchers usually opt to eliminate within-type variation. Provided that in practice it is impossible to observe all circumstances, this implies that the researcher estimates a lower bound of the true level of inequality of opportunity. By using data drawn from 27 Demographic Household Surveys (circa 2008), it is found that lower bound estimates can have substantial measurement error, and that measurement error can vary considerably across countries. As a consequence, lower bound estimates of inequality of opportunity can demand too little redistribution to equalize inequalities due to circumstances and can make the “traditional” cross-country comparisons misleading.
Late-stage formation of Martian chloride salts through ponding and evaporation

Small deposits of chloride salts have been documented at hundreds of locations on Mars through the use of multispectral orbital data. Given the small spatial extent of these deposits, their formation mechanisms, timing, and relation to other aqueous processes in Mars’ history are presently poorly constrained. Here we detail one of the chloride deposits near Meridiani Planum, the location of the Opportunity rover. This chloride deposit likely formed from fluviolacustrine processes, implying an active hydrologic cycle. Late-stage activity led to valley incision in the surrounding highlands and ponding of water to form a lake in a local basin. The lake level eventually rose and breached the drainage divide, leading to significant outflow. The remaining water evaporated and eventually precipitated the chlorides at the lowest levels. Through digital terrain models, the lake and salt flat volumes were used to calculate the salinity of the lake, which at full lake extent was ∼8% of the salinity of Earth’s oceans. Crater density measurements on the terrain cross-cut by the outlet valley constrain the maximum age to 3.60 Ga. This hydrological episode occurred after regional widespread fluvial incision and also post-dates formation of the sulfate bedrock being investigated by Opportunity. We conclude that this and other similar chloride deposits represent some of the last vestiges of habitable surface water on Mars as recorded in the mineralogical record.
How to lose as little as possible

Suppose Alice has a coin with heads probability q and Bob has one with heads probability p > q . Now each of them will toss their coin n times, and Alice will win iff she gets more heads than Bob does. Evidently the game favors Bob, but for the given p , q , what is the choice of n that maximizes Alice's chances of winning? We show that there is an essentially unique value N ( q , p ) of n that maximizes the probability f ( n ) that the weak coin will win, and it satisfies ⌊1/2( p − q ) − 1/2⌋ ≤ N ( q , p ) ≤ ⌈max(1 − p , q )/( p − q )⌉. The analysis uses the multivariate form of Zeilberger's algorithm to find an indicator function J n ( q , p ) such that J > 0 iff n N ( q , p ) followed by a close study of this function, which is a linear combination of two Legendre polynomials. An integration-based algorithm is given for computing N ( q , p ).
Two-element optical array receiver concept demonstration

The conceptual design, theoretical performance, and experimental verification of a two-telescope optical array receiver currently under development at the Jet Propulsion Laboratory, is described in this paper. A brief summary of optical communications theory for array reception of pulsed laser signals is developed, and the impact of coding discussed. The development of the optical detection, array processing, and data-acquisition assemblies required for experimental demonstration is described, and preliminary results obtained in a field environment are presented and evaluated.
Nickel-Catalyzed Coupling Reactions of Alkyl Electrophiles, Including Unactivated Tertiary Halides, To Generate Carbon–Boron Bonds

Through the use of a catalyst formed in situ from NiBr2·diglyme and a pybox ligand (both of which are commercially available), we have achieved our first examples of coupling reactions of unactivated tertiary alkyl electrophiles, as well as our first success with nickel-catalyzed couplings that generate bonds other than C–C bonds. Specifically, we have determined that this catalyst accomplishes Miyaura-type borylations of unactivated tertiary, secondary, and primary alkyl halides with diboron reagents to furnish alkylboronates, a family of compounds with substantial (and expanding) utility, under mild conditions; indeed, the umpolung borylation of a tertiary alkyl bromide can be achieved at a temperature as low as −10 °C. The method exhibits good functional-group compatibility and is regiospecific, both of which can be issues with traditional approaches to the synthesis of alkylboronates. In contrast to seemingly related nickel-catalyzed C–C bond-forming processes, tertiary halides are more reactive than ...