An analysis of cross-correlations in an emerging market

We apply random matrix theory to compare correlation matrix estimators C$C$ obtained from emerging market data. The correlation matrices are constructed from 10 years of daily data for stocks listed on the Johannesburg stock exchange (JSE) from January 1993 to December 2002. We test the spectral properties of C$C$ against random matrix predictions and find some agreement between the distributions of eigenvalues, nearest neighbour spacings, distributions of eigenvector components and the inverse participation ratios for eigenvectors. We show that interpolating both missing data and illiquid trading days with a zero-order hold increases agreement with RMT predictions. For the more realistic estimation of correlations in an emerging market, we suggest a pairwise measured-data correlation matrix. For the data set used, this approach suggests greater temporal stability for the leading eigenvectors. An interpretation of eigenvectors in terms of trading strategies is given, as opposed to classification by economic sectors.     

Overview of nano-drugs characteristics for clinical application: the journey from the entry to the exit point

The ever-increasing number of diseases worldwide requires comprehensive, efficient, and cost-effective modes of treatments. Among various strategies, nanomaterials fulfill most of these criteria. The unique physicochemical properties of nanoparticles have made them a premier choice as a drug or a drug delivery system for the purpose of treatment, and as bio-detectors for disease prognosis. However, the main challenge is the proper consideration of the physical properties of these nanomaterials, while developing them as potential tools for therapeutics and/or diagnostics. In this review, we focus mainly on the characteristics of nanoparticles to develop an effective and sensitive system for clinical purposes. This review will present an overview of the important properties of nanoparticles, through their journey from its route of administration until disposal from the human body after accomplishing targeted functionality. We have chosen cancer as our model disease to explain the potentiality of nano-systems for therapeutics and diagnostics in relation to several organs (intestine, lung, brain, etc.). Furthermore, we have discussed their biodegradability and accumulation probability which can cause unfavorable side effects in healthy human subjects.     

Left inferior frontal gyrus is critical for response inhibition

Background  

Lesion studies in human and non-human primates have linked several different regions of prefrontal cortex (PFC) with the ability to inhibit inappropriate motor responses. However, recent functional neuroimaging studies have specifically implicated right inferior PFC in response inhibition. Right frontal dominance for inhibitory motor control has become a commonly accepted view, although support for this position has not been consistent. Particularly conspicuous is the lack of data on the importance of the homologous region in the left hemisphere. To investigate whether the left inferior frontal gyrus (IFG) is critical for response inhibition, we used neuropsychological methodology with carefully characterized brain lesions in neurological patients.     

A new approach for the large-scale generation of mature dendritic cells from adherent PBMC using roller bottle technology

Background  

Human monocyte-derived DC (mDC) loaded with peptides, protein, tumor cell lysates, or tumor cell RNA, are being tested as vaccines against multiple human malignancies and viral infection with great promise. One of the factors that has limited more widespread use of these vaccines is the need to generate mDC in large scale. Current methods for the large-scale cultivation of mDC in static culture vessels are labor- and time- intensive, and also require many culture vessels. Here, we describe a new method for the large-scale generation of human mDC from human PBMC from leukopheresis or buffy coat products using roller bottles, never attempted before for mDC generation. We have tested this technology using 850 cm² roller bottles compared to conventional T-175 flat-bottom static culture flasks.     

A Convenient Synthesis of 2,4(3H,5H)-Furandione (β-Tetronic Acid)

The chemical versatility of 2,4(3H,5H)-furandione (β-tetronic acid, 1) and its synthetic applicability are of considerable current interest^1b,2a-k. The multifunctional character of this small molecule confers an intriguing synthetic potential which has prompted us to develop synthetic schemes utilizing it as a synthon for certain heterocyclic systems.     

Synthesis of the Dopamine Agonist (-)-Quinpirole

A convenient synthesis and resolution of (-)-trans-4aR,8aR-1-propyl-6-oxo-decahydroquinoline (4) is described. This compound is then converted into the D-2 selective dopamine agonist, (-)-quinpirole hydrochloride (3).     

Investigating Membrane-Mediated Antimicrobial Peptide Interactions with Synchrotron Radiation Far-Infrared Spectroscopy

Synchrotron radiation-based Fourier transform infrared spectroscopy enables access to vibrational information from mid over far infrared to even terahertz domains. This information may prove critical for the elucidation of fundamental bio-molecular phenomena including folding-mediated innate host defence mechanisms. Antimicrobial peptides (AMPs) represent one of such phenomena. These are major effector molecules of the innate immune system, which favour attack on microbial membranes. AMPs recognise and bind to the membranes whereupon they assemble into pores or channels destabilising the membranes leading to cell death. However, specific molecular interactions responsible for antimicrobial activities have yet to be fully understood. Herein we probe such interactions by assessing molecular specific variations in the near-THz 400–40 cm⁻¹ range for defined helical AMP templates in reconstituted phospholipid membranes. In particular, we show that a temperature-dependent spectroscopic analysis, supported by 2D correlative tools, provides direct evidence for the membrane-induced and folding-mediated activity of AMPs. The far-FTIR study offers a direct and information-rich probe of membrane-related antimicrobial interactions.     

Stable nitrogen isotopes in essential versus non-essential amino acids of different plankton size fractions

The stable nitrogen isotope values (delta(15)N) of the essential amino acid (EAA) leucine and the delta(15)N values of six non-essential amino acids (NEAAs) from plankton size fractions from the South China Sea (SCS) were analysed. Data from the SCS were collected during two cruises in July 2003 and 2004 onboard of RV Nghien Cuu Bien. The delta(15)N values of alanine, aspartic acid, glutamic acid and leucine increased with size at all sites. The delta(15)N of glycine did not increase with size, the delta(15)N of tyrosine increased with size only at offshore stations and the delta(15)N of proline increased with size only at inshore stations. We found highly significant correlations between the delta(15)N ratios of leucine to the delta(15)N ratios of glutamic acid, proline, alanine, tyrosine and aspartic acid at oligotrophic sites of enhanced nitrogen fixation. In contrast thereto these correlations were less distinct or absent at more eutrophic sites of low nitrogen fixation. A comparison with an independent data set from the tropical North Atlantic revealed intriguing similar patterns. We interpret these patterns as result of the connected metabolism of EAA and NEAA in zooplankton at sites of nitrogen limitation.     

Hard domain compression of triblock-copolymer gels by high pressure X-ray small-angle scattering

Small-angle X-ray scattering using synchrotron radiation at pressures up to 700 MPa has been performed on triblock-copolymer gels, polystyrene-rubber-polystyrene with poly(ethylene/butylene) as the rubber mid-blocks. A 2-stage pressure behaviour could be verified by comparison of the experimental data with the Tait-equation and a model of pressure screening.     

Characterization of long-chain carboxylic esters with CH3OBOCH 3 + in a small fourier-transform ion cyclotron resonance mass spectrometer

The usefulness of CH₃OBOCH ₃ ⁺ as a chemical ionization reagent was examined by allowing the ion to react with carboxylic esters of various chain lengths in a small Fourier-transform ion cyclotron resonance mass spectrometer equipped with a permanent magnet. CH₃OBOCH ₃ ⁺ is a strong electrophile and readily abstracts an oxygen-containing group from the carboxylic esters. Long-chain esters exclusively lose the alkoxide moiety to give the acylium ion. The same reaction was observed for saturated, unsaturated, branched and cyclic esters. In each case, the acylium ion reacts further with a neutral ester molecule by proton transfer to yield the protonated ester as a secondary product. This remarkably simple product distribution reveals the molecular weight of the ester, the chain length of its acid moiety, and the degree of unsaturation in the acid and alcohol moieties.