Phonon dispersion and lifetimes in MgB2

We measure phonon dispersion and linewidth in a single crystal of MgB_2 along the Gamma-A, Gamma-M and A-L directions using inelastic X-Ray scattering. We use Density Functional Theory to compute the effect of both electron-phonon coupling and anharmonicity on the linewidth, obtaining excellent agreement with experiment. Anomalous broadening of the E_2g phonon mode is found all along Gamma-A. The dominant contribution to the linewidth is always the electron-phonon coupling.Comment: 4 pages, 3 figure

A New Linear Logic for Deadlock-Free Session-Typed Processes

The π -calculus, viewed as a core concurrent programming language, has been used as the target of much research on type systems for concurrency. In this paper we propose a new type system for deadlock-free session-typed π -calculus processes, by integrating two separate lines of work. The first is the propositions-as-types approach by Caires and Pfenning, which provides a linear logic foundation for session types and guarantees deadlock-freedom by forbidding cyclic process connections. The second is Kobayashi’s approach in which types are annotated with priorities so that the type system can check whether or not processes contain genuine cyclic dependencies between communication operations. We combine these two techniques for the first time, and define a new and more expressive variant of classical linear logic with a proof assignment that gives a session type system with Kobayashi-style priorities. This can be seen in three ways: (i) as a new linear logic in which cyclic structures can be derived and a CYCLE -elimination theorem generalises CUT -elimination; (ii) as a logically-based session type system, which is more expressive than Caires and Pfenning’s; (iii) as a logical foundation for Kobayashi’s system, bringing it into the sphere of the propositions-as-types paradigm

Multiparty Session Types as Coherence Proofs

We propose a Curry-Howard correspondence between a language for programming multiparty sessions and a generalisation of Classical Linear Logic (CLL). In this framework, propositions correspond to the local behaviour of a participant in a multiparty session type, proofs to processes, and proof normalisation to executing communications. Our key contribution is generalising duality, from CLL, to a new notion of n-ary compatibility, called coherence. Building on coherence as a principle of compositionality, we generalise the cut rule of CLL to a new rule for composing many processes communicating in a multiparty session. We prove the soundness of our model by showing the admissibility of our new rule, which entails deadlock-freedom via our correspondence

Widening Batson’s Net to Ensnare More Than the Unapologetically Bigoted or Painfully Unimaginative Attorney

In Snyder v. Louisiana, the Supreme Court reaffirmed its commitment to rooting out racially discriminatory jury selection and its belief that the three-step framework established in Batson v. Kentucky is capable of unearthing racially discriminatory peremptory strikes. Yet the Court left in place the talismanic protection available to those who might misuse the peremptory challenge—the unbounded collection of justifications that courts, including the Supreme Court, accept as “race neutral.” To evaluate the Court’s continuing faith in Batson, we conducted a survey of all federal published and unpublished judicial decisions issued in this first decade of the new millennium (2000–2009) that reviewed state or federal trial court rejections of a Batson challenge. In light of this study and studies that have come before, we conclude that Batson is easily avoided through the articulation of a purportedly race-neutral explanation for juror strikes. As a result, there is no reason to believe that Batson is, as the Court suggests, achieving its goal of eliminating race-based jury exclusion and little hope that it will ever do so. In light of our conclusion, this Article proposes an alteration to the Batson framework that we believe would enable trial courts to reduce the role of race in the jury selection process

Directional Reflective Surface Formed via Gradient-Impeding Acoustic Meta-Surfaces

Artificially designed acoustic meta-surfaces have the ability to manipulate sound energy to an extraordinary extent. Here, we report on a new type of directional reflective surface consisting of an array of sub-wavelength Helmholtz resonators with varying internal coiled path lengths, which induce a reflection phase gradient along a planar acoustic meta-surface. The acoustically reshaped reflective surface created by the gradient-impeding meta-surface yields a distinct focal line similar to a parabolic cylinder antenna, and is used for directive sound beamforming. Focused beam steering can be also obtained by repositioning the source (or receiver) off axis, i.e., displaced from the focal line. Besides flat reflective surfaces, complex surfaces such as convex or conformal shapes may be used for sound beamforming, thus facilitating easy application in sound reinforcement systems. Therefore, directional reflective surfaces have promising applications in fields such as acoustic imaging, sonic weaponry, and underwater communicationope

Lumazine Synthase Protein Nanoparticle-Gd(III)-DOTA Conjugate as a T1 contrast agent for high-field MRI

With the applications of magnetic resonance imaging (MRI) at higher magnetic fields increasing, there is demand for MRI contrast agents with improved relaxivity at higher magnetic fields. Macromolecule-based contrast agents, such as protein-based ones, are known to yield significantly higher r(1) relaxivity at low fields, but tend to lose this merit when used as T-1 contrast agents (r(1)/r(2) = 0.5 similar to 1), with their r(1) decreasing and r(2) increasing as magnetic field strength increases. Here, we developed and characterized an in vivo applicable magnetic resonance (MR) positive contrast agent by conjugating Gd(III)-chelating agent complexes to lumazine synthase isolated from Aquifex aeolicus (AaLS). The r(1) relaxivity of Gd(III)-DOTA-AaLS-R108C was 16.49 mM(-1)s(-1) and its r(1)/r(2) ratio was 0.52 at the magnetic field strength of 7 T. The results of 3D MR angiography demonstrated the feasibility of vasculature imaging within 2 h of intravenous injection of the agent and a significant reduction in T-1 values were observed in the tumor region 7 h post-injection in the SCC-7 flank tumor model. Our findings suggest that Gd(III)-DOTA-AaLS-R108C could serve as a potential theranostic nanoplatform at high magnetic field strength.open0

Observed communication semantics for classical processes

Classical Linear Logic (CLL) has long inspired readings of its proofs as communicating processes. Wadler's CP calculus is one of these readings. Wadler gave CP an operational semantics by selecting a subset of the cut-elimination rules of CLL to use as reduction rules. This semantics has an appealing close connection to the logic, but does not resolve the status of the other cut-elimination rules, and does not admit an obvious notion of observational equivalence. We propose a new operational semantics for CP based on the idea of observing communication, and use this semantics to define an intuitively reasonable notion of observational equivalence. To reason about observational equivalence, we use the standard relational denotational semantics of CLL. We show that this denotational semantics is adequate for our operational semantics. This allows us to deduce that, for instance, all the cut-elimination rules of CLL are observational equivalences

Investigating the role of sampler compartments employed by POCIS devices in pesticides sampling

Polar Organic Chemical Integrative Sampler (POCIS) is a passive sampler employed to monitor organic compounds in water (e.g. pesticides, drugs, etc.); in our case consists of a receiving phase, Oasis HLB, enclosed between two polyethersulfone (PES) membranes. In most cases, the analytes were extracted only from the receiving phase but recent works show that some compounds were also adsorbed on the PES membranes. Many aspects on the membrane behaviour are still unknown and this work aims to fill some knowledge gaps exploring the capability of PES membranes to adsorb pesticides. From experiments conducted in a controlled environment, it was seen that more than half of the investigated compounds were adsorbed more effectively by the PES membrane than the Oasis HLB phase. The affinity of these pesticides towards the two sampler compartments, can be explained only partially by the polarity of the compounds. However, a significant adsorption of the most hydrophobic compounds by the PES membrane was noticed, especially for values of LogKow higher than 4. From these experiments, it was possible to calibrate POCIS by comparing the pesticide concentration in water with the amount adsorbed by the two sampler compartments over time, with the estimation of two values of sampling rate for each pesticide (RS,HLB and RS,PES). It was seen that the combination of the two adsorbent substrates allowed to intercept almost all the studied compounds satisfactorily and this behaviour was also confirmed by a field sampling campaign