Statistical mechanical aspects of joint source-channel coding

An MN-Gallager Code over Galois fields, $q$, based on the Dynamical Block Posterior probabilities (DBP) for messages with a given set of autocorrelations is presented with the following main results: (a) for a binary symmetric channel the threshold, $f_c$, is extrapolated for infinite messages using the scaling relation for the median convergence time, $t_{med} \propto 1/(f_c-f)$; (b) a degradation in the threshold is observed as the correlations are enhanced; (c) for a given set of autocorrelations the performance is enhanced as $q$ is increased; (d) the efficiency of the DBP joint source-channel coding is slightly better than the standard gzip compression method; (e) for a given entropy, the performance of the DBP algorithm is a function of the decay of the correlation function over large distances.Comment: 6 page

Beyond MSSM Baryogenesis

Taking the MSSM as an effective low-energy theory, with a cut-off scale of a few TeV, can make significant modifications to the predictions concerning the Higgs and stop sectors. We investigate the consequences of such a scenario for electroweak baryogenesis. We find that the window for MSSM baryogenesis is extended and, most important, can be made significantly more natural. Specifically, it is possible to have one stop lighter than the top and the other significantly lighter than TeV simultaneously with the Higgs mass above the LEP bound. In addition, various aspects concerning CP violation are affected. Most notably, it is possible to have dynamical phases in the bubble walls at tree level, providing CP violating sources for Standard Model fermions.Comment: 20 pages, 2 figures; v2: added reference

Helicity-selective phase-matching and quasi-phase matching of circularly polarized high-order harmonics: Towards chiral attosecond pulses

Phase matching of circularly polarized high-order harmonics driven by counter-rotating bi-chromatic lasers was recently predicted theoretically and demonstrated experimentally. In that work, phase matching was analyzed by assuming that the total energy, spin angular momentum and linear momentum of the photons participating in the process are conserved. Here we propose a new perspective on phase matching of circularly polarized high harmonics. We derive an extended phase matching condition by requiring a new propagation matching condition between the classical vectorial bi-chromatic laser pump and harmonics fields. This allows us to include the influence of the laser pulse envelopes on phase matching. We find that the helicity dependent phase matching facilitates generation of high harmonics beams with a high degree of chirality. Indeed, we present an experimentally measured chiral spectrum that can support a train of attosecond pulses with a high degree of circular polarization. Moreover, while the degree of circularity of the most intense pulse approaches unity, all other pulses exhibit reduced circularity. This feature suggests the possibility of using a train of attosecond pulses as an isolated attosecond probe for chiral-sensitive experiments

A dynamical symmetry triad in high-harmonic generation revealed by attosecond recollision control

A key element of optical spectroscopy is the link between observable selection rules and the underlying symmetries of an investigated physical system. Typically, selection rules directly relate to the sample properties probed by light, yielding information on crystalline structure or chirality, for example. Considering light-matter coupling more broadly may extend the scope of detectable symmetries, to also include those directly arising from the interaction. In this letter, we experimentally demonstrate an emerging class of symmetries in the electromagnetic field emitted by a strongly driven atomic system. Specifically, generating high-harmonic radiation with attosecond-controlled two-color fields, we find different sets of allowed and forbidden harmonic orders. Generalizing symmetry considerations of circularly polarized high-harmonic generation, we interpret these selection rules as a complete triad of dynamical symmetries. We expect such emergent symmetries also for multi-atomic and condensed-matter systems, encoded in the spectral and spatial features of the radiation field. Notably, the observed phenomenon gives robust access to chiral processes with few-attosecond time precision

Inherently Emissive Puromycin Analogues for Live Cell Labelling

Abstract: Puromycin derivatives containing an emissive thieno[3,4‐d]‐pyrimidine core, modified with azetidine and 3,3‐difluoroazetidine as Me2N surrogates, exhibit translation inhibition and bactericidal activity similar to the natural antibiotic. The analogues are capable of cellular puromycylation of nascent peptides, generating emissive products without any follow‐up chemistry. The 3,3‐difluoroazetidine‐containing analogue is shown to fluorescently label newly translated peptides and be visualized in both live and fixed HEK293T cells and rat hippocampal neurons

Astrophysical Implications of a Visible Dark Matter Sector from a Custodially Warped-GUT

We explore, within the warped extra dimensional framework, the possibility of finding anti-matter signals in cosmic rays (CRs) from dark matter (DM) annihilation. Exchange of order 100 GeV radion, an integral part of our setup, generically results in Sommerfeld enhancement of the annihilation rate for TeV DM mass. No dark sector is required to obtain boosted annihilation cross sections. A mild hierarchy between the radion and DM masses can be natural due to the pseudo-Goldstone boson nature of the radion. Implications of Sommerfeld enhancement in warped grand unified theory (GUT) models, where proton stability implies a DM candidate, are studied. We show, via partially unified Pati-Salam group, how to incorporate a custodial symmetry for Z->b\bar b into the GUT framework such that a few TeV Kaluza-Klein (KK) mass scale is allowed by precision tests. The model with smallest fully unified SO(10) representation allows us to decouple the DM from the electroweak sector. Thus, a correct DM relic density is obtained and direct detection bounds are satisfied. Looking at robust CR observables, a possible future signal in the \bar p / p flux ratio is found. We show how to embed a similar custodial symmetry for the right handed tau, allowing it to be strongly coupled to KK particles. Such a scenario might lead to observed signal in CR positrons; however, the DM candidate in this case can not constitute all of the DM in the universe. Independently of the above, the strong coupling between KK particles and tau's can lead to striking LHC signals.Comment: 53 pages, 9 figure

Asymmetric Higgsino Dark Matter

In the supersymmetric framework, a higgsino asymmetry exists in the universe before the electroweak phase transition. We investigate whether the higgsino is a viable asymmetric dark matter candidate. We find that this is indeed possible. The gauginos, squarks and sleptons must all be very heavy, such that the only electroweak-scale superpartners are the higgsinos. The temperature of the electroweak phase transition must be in the (1-10) GeV range.Comment: 5 pages, 2 figure

Interlocked attosecond pulse trains in slightly bi-elliptical high harmonic generation

The ellipticity of high harmonics driven by bi-chromatic (e.g. w - 2w) fully tuned by varying the polarization of the pump components. In order to start revealing the underlying mechanism of this control, we explore a relatively simple regime of this scheme that still gives rise to full control over the harmonics ellipticities. In this regime, the pumps are only slightly elliptical and the high harmonic radiation consists of two (different) interlocked attosecond pulse trains (APTs). We formulate a semi-analytic model that maps the high harmonic ellipticity to properties of the APTs harmonic decompositions. Utilizing this model, we reconstruct these APTs variables from measurements of the high harmonics ellipticities. This ellipticity-resolved spectroscopy of interlocked APTs may be useful for ultrafast probing of chiral degrees of freedom

An N-Terminal Extension to UBA5 Adenylation Domain Boosts UFM1 Activation: Isoform-Specific Differences in Ubiquitin-like Protein Activation

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Modification of proteins by the ubiquitin-like protein, UFM1, requires activation of UFM1 by the E1-activating enzyme, UBA5. In humans, UBA5 possesses two isoforms, each comprising an adenylation domain, but only one containing an N-terminal extension. Currently, the role of the N-terminal extension in UFM1 activation is not clear. Here we provide structural and biochemical data on UBA5 N-terminal extension to understand its contribution to UFM1 activation. The crystal structures of the UBA5 long isoform bound to ATP with and without UFM1 show that the N-terminus not only is directly involved in ATP binding but also affects how the adenylation domain interacts with ATP. Surprisingly, in the presence of the N-terminus, UBA5 no longer retains the 1:2 ratio of ATP to UBA5, but rather this becomes a 1:1 ratio. Accordingly, the N-terminus significantly increases the affinity of ATP to UBA5. Finally, the N-terminus, although not directly involved in the E2 binding, stimulates transfer of UFM1 from UBA5 to the E2, UFC1.Marie Curie Career Integration GrantIsrael Science FoundationIsraeli Cancer Associatio