Pentaquark Masses in Chiral Perturbation Theory

Heavy baryon chiral perturbation theory for pentaquarks is applied beyond leading order. The mass splitting in the pentaquark anti-decuplet is calculated up to NNLO. An expansion in the coupling of pentaquarks to non-exotic baryons simplifies calculations and makes the pentaquark masses insensitive to the pentaquark-nucleon mass difference. The possibility of determining coupling constants in the chiral Lagrangian on the lattice is discussed. Both positive and negative parities are considered.Comment: 11 pages; reference added, minor changes in wordin

Probing the time variability of five Fe low broad absorption line quasars

We study the time variability of five Fe Low ionization Broad Absorption Line (FeLoBAL) QSOs using repeated spectroscopic observations with the 2m telescope at IUCAA Girawali observatory (IGO) spanning an interval of upto 10 years. We report a dramatic variation in Al III and Fe III fine-structure lines in the spectra of SDSS J221511.93-004549.9 (z_em ~ 1.478). However, there is no such strong variability shown by the C IV absorption. This source is known to be unusual with (i) the continuum emission dominated by Fe emission lines, (ii) Fe III absorption being stronger than Fe II and (iii) the apparent ratio of Fe III UV 48 to Fe III UV 34 absorption suggesting an inverted population ratio. This is the first reported detection of time variability in the Fe III fine-structure lines in QSO spectra. There is a strong reduction in the absorption strength of these lines between year 2000 and 2008. Using the template fitting techniques, we show that the apparent inversion of strength of UV lines could be related to the complex spectral energy distribution of this QSO. The observed variability can be related to change in the ionization state of the gas or due to transverse motion of this absorbing gas. The shortest variability timescale of Al III line gives a lower limit on the electron density of the absorbing gas as n_e >= 1.1 x 10^4 cm^-3. The remaining 4 FeLoBALs do not show any changes beyond the measurement uncertainties either in optical depth or in the velocity structure. We present the long-term photometric light curve for all of our sources. Among them only SDSS J221511.93-004549.9 shows significant (>= 0.2 mag) variability.Comment: 15 pages, 9 figures, 3 tables, Accepted for publication in MNRA

Minimal Universal Two-qubit Quantum Circuits

We give quantum circuits that simulate an arbitrary two-qubit unitary operator up to global phase. For several quantum gate libraries we prove that gate counts are optimal in worst and average cases. Our lower and upper bounds compare favorably to previously published results. Temporary storage is not used because it tends to be expensive in physical implementations. For each gate library, best gate counts can be achieved by a single universal circuit. To compute gate parameters in universal circuits, we only use closed-form algebraic expressions, and in particular do not rely on matrix exponentials. Our algorithm has been coded in C++.Comment: 8 pages, 2 tables and 4 figures. v3 adds a discussion of asymetry between Rx, Ry and Rz gates and describes a subtle circuit design problem arising when Ry gates are not available. v2 sharpens one of the loose bounds in v1. Proof techniques in v2 are noticeably revamped: they now rely less on circuit identities and more on directly-computed invariants of two-qubit operators. This makes proofs more constructive and easier to interpret as algorithm

Drug-Excipient Compatibility Studies in Formulation Development: Current Trends and Techniques

The safety, efficacy, quality and stability of a formulation are the cornerstones of any new drug development process. In order to consistently maintain these attributes in a finished dosage form, it is important to have a comprehensive understanding of the physico-chemical characteristics of the active pharmaceutical ingredient (API), as well as all other components (e.g. excipients, manufacturing aids, packaging materials) of the drug product. In a new drug development process, a detailed characterization of the API and other formulation components is usually carried out during the preformulation stage. The preformulation stage involves characterization of several aspects of the API including solubility, dissolution, permeability, polymorph/salt screening, stability (solidstate and solution-state), ionization properties, particle size distribution, API-excipient compatibilities etc. [1]. Excipients are ubiquitous to virtually every pharmaceutical formulation, and facilitate the manufacture, stability, administration, delivery of the API, and/or provide other functionalities to the dosage form. Excipients are used to improve processing (e.g. improving powder flow [2, 3], powder compactibility [4-6] etc.), enhance aesthetics (e.g. identification, branding etc. [7]), optimize product performance (e.g. modified drug-release [8-11]), and/or to facilitate patient compliance (e.g. taste masking [12-15]). They may constitute anywhere from 1 to 99 % of the total formulation mass. Due to the intimate contact of the API with one or more excipients in a formulation, there exists a likelihood of physical and/or chemical interactions between them. Any such interactions may result in a negative impact on the physical, stability or performance attributes of the drug product [16, 17]. The choice of excipients is of crucial importance to avoid these negative effects, and to facilitate the development of a robust and an effective formulation [18-20]. Thus, for a rational selection of excipients, screening of excipient-API compatibility is recognized as an important aspect of formulation development. Moreover, the USFDA’s 21st century current Good Manufacturing Practices (cGMP) initiative and International Council on Harmonization (ICH) Q8 guidelines encourage the pharmaceutical manufacturers to apply Quality by Design (QbD) principles in their drug development process [21, 22]. These guidelines include expectations of a clear understanding of any interactions between the formulation components. Moreover, recent advances in various thermal and non-thermal analytical techniques have led to an improved efficiency in the detection, monitoring and prevention of the incompatibilities early in the drug development process [23, 24]. This article aims to provide a brief overview of the nature of drug-excipient incompatibilities; as well as current trends and techniques used to evaluate these compatibilities in formulation development

A Regimen of Taxol, Ifosfamide, and Platinum for Recurrent Advanced Squamous Cell Cancer of the Anal Canal

The typically recommended chemotherapy options in metastatic anal cancer generally yield partial remissions with limited benefit for the majority of patients. TIP is a regimen containing paclitaxel (Taxol), ifosfamide, and cisplatin that is known to have significant activity in patients with squamous cell cancers of the head and neck as well as in cervical cancer, both of which are malignancies strongly associated with oncogenic strains of human papilloma virus (HPV). Interestingly, squamous cell cancer of the anal canal shares an almost identical pathophysiology including causal association with HPV. Due to this, we chose to use the TIP regimen to treat patients with advanced anal cancer at our institution and report our findings on three such consecutive patients. All the patients tolerated the regimen well with manageable side effects and had excellent responses with complete resolution of PET activity after treatment. Our observations suggest that TIP is highly active for squamous cell cancer of the anal canal and warrants further study in the treatment of this disease

Band inversion driven by electronic correlations at the (111) LaAlO3_3/SrTiO3_3 interface

Quantum confinement at complex oxide interfaces establishes an intricate hierarchy of the strongly correlated $d$-orbitals which is widely recognized as a source of emergent physics. The most prominent example is the (001) LaAlO$_3$/SrTiO$_3$(LAO/STO) interface, which features a dome-shaped phase diagram of superconducting critical temperature and spin-orbit coupling (SOC) as a function of electrostatic doping, arising from a selective occupancy of $t_{2g}$ orbitals of different character. Here we study (111)-oriented LAO/STO interfaces - where the three $t_{2g}$ orbitals contribute equally to the sub-band states caused by confinement - and investigate the impact of this unique feature on electronic transport. We show that transport occurs through two sets of electron-like sub-bands, and the carrier density of one of the sets shows a non-monotonic dependence on the sample conductance. Using tight-binding modeling, we demonstrate that this behavior stems from a band inversion driven by on-site Coulomb interactions. The balanced contribution of all $t_{2g}$ orbitals to electronic transport is shown to result in strong SOC with reduced electrostatic modulation.Comment: 5 pages, 4 figures, (+ supplemental material

Emulating Thin Clients and Voice-over-IP with Wane

Volume 2 Issue 8 (August 2014