More on nucleon-nucleon cross sections in symmetric and asymmetric matter

Following a recent work, we present numerical results for total two-nucleon effective cross sections in isospin symmetric and asymmetric matter. The present calculations include the additional effect of Pauli blocking of the final states.Comment: 9 pages, no figures, 5 table

Analysis and Architecture Design of DSPACE, a Digital Signal Processor for space applications

The request of digital signal processing performed on satellites or spacecraft is greatly increased in past years, however the European Space Agency (ESA) has not got a suitable device for these applications made in Europe area. ESA is currently forced to address to United States (US) made alternatives but the exportation of those devices is restricted by the International Traffic in Arms Regulations (ITAR) and this places ESA in a dependent position. The DSPACE project aim to solve this lack providing a new Digital Signal Processor (DSP), as an intellectual property, and a software tool-chain to exploit its features. The first part of this thesis work regarded an analysis of the state-of-the-art and the practical solutions in order to identify a target technology and a reference architecture. The second part of this work concerned a detailed definitions of the DSPACE core architecture and features. Moreover a complete decode & dispatch VHDL model, with a formal functional verification, was realized. The third part of this work regarded two caches modelling, the instruction and the data cache, that are two essential components of the DSPACE core. This thesis work was concluded with the first functional simulations coming from the DSPACE model and considerations about the resource occupation of the core

Radiative Scaling Neutrino Mass with A4A_4 Symmetry

A new idea for neutrino mass was proposed recently, where its smallness is not due to the seesaw mechanism, i.e. not inversely proportional to some large mass scale. It comes from a one-loop mechanism with dark matter in the loop consisting of singlet Majorana fermions $N_i$ with masses of order 10 keV and neutrino masses are scaled down from them by factors of about $10^{-5}$. We discuss how this model may be implemented with the non-Abelian discrete symmetry $A_4$ for neutrino mixing, and consider the phenomenology of $N_i$ as well as the extra scalar doublet $(\eta^+,\eta^0)$.Comment: 11 pages, 1 figur

Design, Synthesis, and Pharmacological Activities of Dynorphin A Analogs Cyclized by Ring-Closing Metathesis

Dynorphin A (Dyn A) is an endogenous ligand for kappa (κ) opioid receptors. To restrict the conformational mobility, we synthesized several cyclic Dyn A-(1-11)NH2 analogs on solid phase utilizing ring-closing metathesis (RCM) between the side chains of allylglycine (AllGly) residues incorporated in positions 2, 5 and/or 8. Cyclizations between the side chains of AllGly gave reasonable yields (56–74%) of all of the desired cyclic peptides. Both the cis and trans isomers were obtained for all of the cyclic peptides, with the ratio of cis to trans isomers depending on the position and stereochemistry of the AllGly. Most of the cyclic Dyn A-(1-11)NH2 analogs examined exhibit low nanomolar binding affinity for κ opioid receptors (Ki = 0.84–11 nM). In two of the three cases the configuration of the double bond has a significant influence on the opioid receptor affinity and agonist potency. All of the peptides inhibited adenylyl cyclase (AC) activity in a concentration-dependent manner with full or close to full agonist activity. These potent Dyn A analogs are the first ones cyclized by RCM

What Does Low Energy Physics Tell Us About The Zero Momentum Gluon Propagator

The connection between QCD, a nonlocal Nambu--Jona-Lasinio type model and the Landau gauge gluon propagator is explored. This two point function is parameterized by a functional form which is compatible with Dyson-Schwinger and lattice QCD results. Demanding the nonlocal model to reproduce the experimental values for the pion mass, the pion decay constant, $\Gamma_{\pi \rightarrow \gamma\gamma}$ and the light quark condensate we conclude that low energy physics does not distinguish between the so-called decoupling and scaling solutions of the Dyson-Schwinger equations. This result means that, provided that the model parameters are chosen appropriately, one is free to chose any of the above scenarios. Furthermore, the nonlocal Nambu--Jona-Lasinio quark model considered here is chiral invariant and satisfies the GMOR relation at the 1% level of precision.Comment: 12 pages, 4 figures, 2 table

Polyimides containing pendent siloxane groups

The incorporation of siloxane units into the backbone of aromatic polyimides has been shown to impart certain advantages over the unmodified polyimides. These include enhanced solubility, lower moisture adsorption, lower dielectric constant, improved toughness and surface modification. Also, when exposed to an atomic oxygen environment these materials form an in-situ silicate (SiO2) surface coating which protects the underlying material from further erosion. These unique advantages make polyimide-siloxanes useful in a variety of electronic and aerospace applications. As part of an effort on high performance polymeric materials for potential aerospace applications, polyimides containing pendent siloxane groups are under study. These materials were prepared by reacting a functionalized siloxane compound with polyimides containing benzhydrol groups. Thin films of the polymers exhibited glass transition temperatures ranging from 167 to 235 C. Tensile strengths and moduli measured at 23 C ranged from 11 to 14 ksi and 250 to 450 ksi, respectively. The dielectric constant was lowered substantially from that of the unmodified polyimide

Coastal Erosion in Southern Maine: An Evaluation of Coastal Armoring Structures and Their Effectiveness

The purpose of this thesis is to evaluate the effectiveness of hard coastal armoring structures and their cumulative effect upon the shape and volume of sediment of the beach profile at which they are implemented. Four coastal sites in Southern Maine were selected for study: Wells Beach, Higgins Beach, Scarborough Beach, and Laudholm Beach. The years 2006 – 2014 were examined for seasonal meteorological, volumetric, and sediment characteristic changes at each location. Profiles established at these beaches are protected by a variety of hard armoring structures, such as jetties, concrete seawalls, and stone revetments. Unarmored profiles on these beaches are also evaluated to compare sediment loss and profile shape due to natural processes and as a direct result of the structure itself. Primary analysis of volumetric changes in the direction perpendicular to the beach profile is done using the Empirical Orthogonal Eigenfunction (EOF) method. The EOF method establishes a set of modes that account for variances within the profile. These modes can be combined to produce the overall profile shape over a specified time frame. The first mode accounts for the greatest possible variance in profile data, and thus represents the dominant profile of the beach. The second and third modes – which represent bar and berm formation patterns – reveal littoral transport patterns along the profile due to seasonal weather conditions. The Even/Odd method provides a supplementary analysis of the impact hard armoring structures have upon the beach in the direction parallel (cross- shore) to the profile. Volume changes on the updrift and downdrift sides of the structure vary depending upon the type of structure implemented and the direction of longshore transport. In general, an analysis of erosion and accretion using the EOF and Even/Odd methods reveals that sediment on the majority of beaches in Southern Maine is being transported offshore at a rate faster than it is being replenished. Profile data and meteorological trends examined using the EOF method reveal that vertical seawalls and sloped stone revetments cause significant erosion in the nearshore, creating a channel in the beach face. Deposition of this sediment occurs offshore during the winter months. In some instances, storm bars are formed. However, the majority of hard armoring structures experience sediment transport and deposition farther offshore. This pattern does not occur as prominently on unarmored beaches. Similarly, hard armoring structures interrupt cross-shore sediment transport patterns and cause significant accretion on the updrift side and erosion on the downdrift side during storm events. Skewness calculations support these findings: a negative skew typically characterizes profiles protected by or adjacent to armoring structures, signifying erosive conditions. Natural erosive and depositional environments are preserved at unarmored beaches. Sea level rise and increases in storm intensity are likely to occur due to climate change in the coming decades. The ultimate effect these changes in weather could have upon patterns of erosion is unknown at this time, but it is assumed that sediment will continue to be transported offshore at rapid rates as wave runup and tidal reaches move farther inland. This thesis briefly touches upon storm classification and its effect upon erosion, as well as climate change predictions that could impact shoreline recession and erosion trends. Shoreline recession is approximated using the Bruun rule