Large-Scale Self-Consistent Nuclear Mass Calculations

The program of systematic large-scale self-consistent nuclear mass calculations that is based on the nuclear density functional theory represents a rich scientific agenda that is closely aligned with the main research directions in modern nuclear structure and astrophysics, especially the radioactive nuclear beam physics. The quest for the microscopic understanding of the phenomenon of nuclear binding represents, in fact, a number of fundamental and crucial questions of the quantum many-body problem, including the proper treatment of correlations and dynamics in the presence of symmetry breaking. Recent advances and open problems in the field of nuclear mass calculations are presented and discussed.Comment: 21 pages, 5 figures, submitted to International Journal of Mass Spectrometr

On-the-Job Search, Minimum Wages, and Labor Market Outcomes in an Equilibrium Bargaining Framework

We look at the impact of a binding minimum wage on labor market outcomes and welfare distributions in a partial equilibrium model of matching and bargaining in the presence of on-the-job search. We use two different specifications of the Nash bargaining problem. In one, firms engage in a Bertrand competition for the services of an individual, as in Postel-Vinay and Robin (2002). In the other, firms do not engage in such competitions, and the outside option used in bargaining is always the value of unemployed search. We estimate both bargaining specifications using a Method of Simulated Moments estimator applied to data from a recent wave of the Survey of Income and Program Participation. Even though individuals will be paid the minimum wage for a small proportion of their labor market careers, we find significant effects of the minimum wage on the ex ante value of labor market careers, particularly in the case of Bertrand competition between firms. An important futures goal of this research agenda is to develop tests capable of determining which bargaining framework is more consistent with observed patterns of turnover and wage change at the individual level.Minimum wage, On-the-job search, Renegotiation, Matching functions

Expression and purification of an NSD3-GB1 fusion protein as a way to study the structure of complex formation with Brd4 ET.

The BRD4 protein belongs to the bromodomain and extraterminal domain (BET) family of eukaryotic transcription factors, and is linked to several types of cancer, inflammation, and obesity. Bromodomain inhibitors are currently in clinical trials for treating several types of cancer however, bromodomains are not exclusive to the BET family. The ET domain is exclusive to the BET family and is responsible for recruiting chromatin-modifying factors that result in transcriptional co-activation. One example of these factors is nuclear receptor binding SET domain protein 3 (NSD3), which promotes cell cycle progression through methylation of a lysine residue on histone H3. Due to its role in cell cycle regulation, NSD3 is essential in maintaining acute myeloid leukemia. Previous studies using fragments of a 645-residue short isoform of NSD3 showed that residues 100-263 were sufficient to maintain binding with the ET domain with an affinity of 2.1 μM. Subsequent studies using isothermal titration calorimetry (ITC) and nuclear magnetic resonance (NMR) indicated that residues 152-163 of NSD3 form a complex with the ET domain and reported a Kd of 140 μM. However, unpublished work from our laboratory using NMR showed that titration of the same peptide into ET yielded a Kd of 3mM, this suggests that more residues are important in the interaction. Thus, the goal of my research is to define the interacting region between NSD3 and the BRD4 ET domain. Prior experiments in the Foster lab showed that NSD3 residues 100-263 are not soluble at concentrations required to characterize its structure. These residues are soluble when fused to glutathione-S-transferase (GST); however, removal of this GST 'tag' resulted in protein precipitation. To overcome this solubility problem, we fused NSD3 100-263 to a GB1 solubility tag. GB1 has a well-defined NMR spectrum and has shown to significantly increase the solubility of small peptides to which it is fused. There is no need to remove the GB1 tag as long as its signals don't overlap or convolute the spectrum of the NSD3-BRD4 complex. Two-dimensional 1H-15N NMR spectra will be recorded of free GB1, the NSD3-GB1 fusion and the BRD4 ET domain, these will serve as reference spectra. To characterize the interaction between NSD3 and BRD4 ET, NMR spectra will be recorded of labeled ET domain in the presence of unlabeled NSD3 and labeled NSD3 in the presence of unlabeled ET. Because signals in the spectra can be assigned to individual amino acids, overlaying the interaction spectra with their reference spectra will show shifted peaks for the residues involved in the interaction. Based on previous data, it is expected that more than just residues 152-163 of NSD3 will be shifted, indicating that they are involved in the interaction with the ET domain. Overall, elucidating the mechanism of interaction between the BRD4 ET domain and NSD3 will give a clearer picture into the specific interactions of the ET domain. Specifically, a conserved mechanism of interaction between ET and its binding partners would be of interest and serve as a guide to treatments specifically targeting the BET family.National Institutes of HealthNo embargoAcademic Major: Biochemistr

An Object-Based Interpretation of Audiovisual Processing

Visual cues help listeners follow conversation in a complex acoustic environment. Many audiovisual research studies focus on how sensory cues are combined to optimize perception, either in terms of minimizing the uncertainty in the sensory estimate or maximizing intelligibility, particularly in speech understanding. From an auditory perception perspective, a fundamental question that has not been fully addressed is how visual information aids the ability to select and focus on one auditory object in the presence of competing sounds in a busy auditory scene. In this chapter, audiovisual integration is presented from an object-based attention viewpoint. In particular, it is argued that a stricter delineation of the concepts of multisensory integration versus binding would facilitate a deeper understanding of the nature of how information is combined across senses. Furthermore, using an object-based theoretical framework to distinguish binding as a distinct form of multisensory integration generates testable hypotheses with behavioral predictions that can account for different aspects of multisensory interactions. In this chapter, classic multisensory illusion paradigms are revisited and discussed in the context of multisensory binding. The chapter also describes multisensory experiments that focus on addressing how visual stimuli help listeners parse complex auditory scenes. Finally, it concludes with a discussion of the potential mechanisms by which audiovisual processing might resolve competition between concurrent sounds in order to solve the cocktail party problem

6-O-Nucleotidyltransferase: an aminoglycoside-modifying enzyme specific for streptomycin/streptidine

Aminoglycosides are especially useful for the treatment of hospital-acquired infections. The main problem for the application of these antibiotics is the presence of bacterial resistance enzymes, in particular, nucleotidyltransferases (ANTs). These enzymes catalyze the transfer of an adenylyl group from the MgATP complex to different positions of the antibiotic. To understand the mechanisms that lead to antibiotic inactivation, we have performed a comprehensive experimental analysis of one of those enzymes. The 6-O- nucleotidyltransferase enzyme (ANT(6)) from Bacillus subtilis was cloned, overexpressed and purified in E. coli. The kinetic parameters revealed a narrow specificity of the ANT(6) for MgATP/streptomycin as substrates. The binding epitope of the streptomycin recognized by the ANT(6) is the streptidine moiety. Therefore, the use of streptidine as a “decoy acceptor” allows the recovery of the antibiotic activity of streptomycin E. coli cells that are overexpressing the ANT(6).This investigation was supported by a research grant of the Span-ish research “Dirección General de Investigación" CTQ2013-45538-PPeer reviewe

Two-body problem in periodic potentials

We investigate the problem of two atoms interacting via a short range s-wave potential in the presence of a deep optical lattice of arbitrary dimension $D$. Using a tight binding approach, we derive analytical results for the properties of the bound state and the scattering amplitude. We show that the tunneling through the barriers induces a dimensional crossover from a confined regime at high energy to an anisotropic three dimensional regime at low energy. The critical value of the scattering length needed to form a two-body bound state shows a logaritmic dependence on the tunneling rate for D=1 and a power law for $D>1$. For the special case D=1, we also compare our analytical predictions with exact numerics, finding remarkably good agreement

Autotuning control structures for reliability-driven dynamic binding

Abstract-This paper explores a formally grounded approach to solve the problem of dynamic binding in serviceoriented software architecture. Dynamic binding is a widely adopted mean to automatically bind exposed software interfaces to actual implementations. The execution of an operation on one or another implementation, though providing the same result, could turn out in different quality of service, e.g. due to failure occurrence. Dynamic binding is thus of primary importance to achieve what in the Software Engineering domain is called "selfadaptiveness", the capability to preserve a desired quality of service, if this is feasible. It is important to reach this goal also in the presence of environmental fluctuations -a route congestion increase -or even abrupt variations -a server breakdown. A quite general dynamic binding problem is here reformulated as a discrete-time feedback control one, and the use of autotuning techniques is discussed, extending previous research, in a view to guaranteeing the desired quality of service without the need for computationally-intensive optimisations

Magnetic impurities coupled to quantum antiferromagnets in one dimension

Magnetic impurities coupled antiferromagnetically to a one-dimensional Heisenberg model are studied by numerical diagonalization of chains of finite clusters. By calculating the binding energy and the correlation function, it is shown that a local singlet develops around each impurity. This holds true for systems with a single impurity, with two impurities, and for impurities forming a lattice. The local character of the singlet is found to be little affected by the presence of other impurity spins. A small effective interaction is found between a pair of impurity spins, which oscillates depending on impurity distances. For impurity lattices, the energy spectrum shows a gap which is found to be much smaller than the binding energy per impurity if the coupling constants are small. For larger coupling constants, it increases to the same order of magnitude as the binding energy, indicating that a local singlet is broken to create excited states. Impurity lattices with ferromagnetic couplings are also studied and their connection to the Haldane problem is discussed.Comment: 25 pages, plain TeX, 17 figures available on request, to be publised in Phys. Rev.

Binding energies of hydrogen-like impurities in a semiconductor in intense terahertz laser fields

A detailed theoretical study is presented for the influence of linearly polarised intense terahertz (THz) laser radiation on energy states of hydrogen-like impurities in semiconductors. The dependence of the binding energy for 1s and 2p states on intensity and frequency of the THz radiation has been examined.Comment: 14 pages, 4 figure

Summary Report: Project Terra Research Meeting

Developing the conservation of earthen architectural Heritage -- as a science, a field of study, a professional practice, and a social endeavor -- is the overall objective of Project Terra