Preliminary report on allelic variation of Th2R and Th3R region of the circumsporozoite protein of plasmodium falciparum from Kokap Yogyakarta Province Indonesia

Allelic variation on the Th2R and Th3R non-repetitive epitope regions of the Circumsporozoit Protein (CSP) is a well known phenomenon among Plasmodium falciparum population within different regions or geographical situations. However, such information originated from Indonesian plasmodium population is still not available. Studies have been initiated on Indonesian Plasmodium populations, aiming to identify the sequence variation of the gene encoding Th2R and Th3R epitope region of the CSP molecules of P. falciparum from malaria endemic areas of Indonesia. At the initial stage of these studies P. falciparum infected blood had been collected from patients living in endemic areas of Kokap district, Yogyakarta Province, Indonesia. Genomic DNA were isolated from microscopically positive samples and the gene encoding non-repetitive T cell epitope region of the CSP molecules were amplified by Polymerase Chain Reaction (PCR) using primers designed based on conserved regions of published sequences. The DNA PCR amplification products were purified and sequenced directly using ABI Prism 377 type Automatic DNA Sequencer, and the allelic type of the Th2R and Th3R epitopes were analyzed. The parallel PCR products were also dotted onto replicate nylon membranes and the Th2R and Th3R epitopes were typed using Sequence Specific Oligonucleotide Probes. The results indicated that from 18 samples which were successfully sequenced the Th2R epitope types were all Th2R*05 (100%), whiles on the Th3R locus 72.2% were Th3R*01and 27.8% were Th3R*04. If these data combined with sequences from other countries, it seems that P. falciparum from Indonesian isolates is more closely related to PNG and Thailand rather than to Gambia and Brazil populations. Keywords: Plasmodium falciparuni - Th2R - Th3R - Circum Sporozoite Protein - SSO

On the Number of Facets of Three-Dimensional Dirichlet Stereohedra III: Full Cubic Groups

We are interested in the maximum possible number of facets that Dirichlet stereohedra for three-dimensional crystallographic groups can have. The problem for non-cubic groups was studied in previous papers by D. Bochis and the second author (Discrete Comput. Geom. 25:3 (2001), 419-444, and Beitr. Algebra Geom., 47:1 (2006), 89-120). This paper deals with ''full'' cubic groups, while ''quarter'' cubic groups are left for a subsequent paper. Here, ''full'' and ''quarter'' refers to the recent classification of three-dimensional crystallographic groups by Conway, Delgado-Friedrichs, Huson and Thurston (math.MG/9911185, Beitr. Algebra Geom. 42.2 (2001), 475-507). Our main result in this paper is that Dirichlet stereohedra for any of the 27 full groups cannot have more than 25 facets. We also find stereohedra with 17 facets for one of these groups.Comment: 28 pages, 12 figures. Changes from v1: apart of some editing (mostly at the end of the introduction) and addition of references, an appendix has been added, which analyzes the case where the base point does not have trivial stabilize

The LOFAR ling baseline snapshot calibrator survey

Aims:\ud An efficient means of locating calibrator sources for international LOw Frequency ARray (LOFAR) is developed and used to determine the average density of usable calibrator sources on the sky for subarcsecond observations at 140 MHz.\ud \ud Methods\ud We used the multi-beaming capability of LOFAR to conduct a fast and computationally inexpensive survey with the full international LOFAR array. Sources were preselected on the basis of 325 MHz arcminute-scale flux density using existing catalogues. By observing 30 different sources in each of the 12 sets of pointings per hour, we were able to inspect 630 sources in two hours to determine if they possess a sufficiently bright compact component to be usable as LOFAR delay calibrators.\ud \ud Results:\ud More than 40% of the observed sources are detected on multiple baselines between international stations and 86 are classified as satisfactory calibrators. We show that a flat low-frequency spectrum (from 74 to 325 MHz) is the best predictor of compactness at 140 MHz. We extrapolate from our sample to show that the sky density of calibrators that are sufficiently bright to calibrate dispersive and non-dispersive delays for the international LOFAR using existing methods is 1.0 per square degree.\ud \ud Conclusions:\ud The observed density of satisfactory delay calibrator sources means that observations with international LOFAR should be possible at virtually any point in the sky provided that a fast and efficient search, using the methodology described here, is conducted prior to the observation to identify the best calibrator

Electron Paramagnetic Resonance as a Structural Tool to Study Graphene Oxide: Potential-Dependence of the EPR Response

Electron paramagnetic resonance (EPR) spectroscopy is reported as a tool to probe the behavior of graphene oxide (GO). The potential-dependent response of GO is reported for the first time and correlated with the observed electrochemical response. The EPR signal, deconvoluted into two constituent parts, was used along with lineshape simulations and the temperature dependence to probe the electrochemical processes. The EPR signal is found to be well described by two components. The narrower one is associated with unpaired electrons on localized functional groups and shows a reversible increase as GO is biased to positive potentials. The Curie behavior of this component suggests that it increases because of the formation of stable radical species, such as semiquinones, derived from quinones and other carbonyl functional groups found on GO. A stronger dependence of the narrow component with potential, and an elevated g value over 2.0034, is found in alkaline conditions compared to neutral electrolytes, reflecting the greater stability of seminquinone-like species at higher pH. By contrast, the second, broader component of the EPR signal was found to be potential-independent. The EPR approach described here offers a solution phase alternative, which can be employed under electrochemical control, to techniques such as X-ray photoelectron spectroscopy and Raman spectroscopy, as a means to probe the structure of GO and related materials

Kaon-Nucleus Drell-Yan Processes and Kaon Structure Functions

We investigate the information which could be obtained from Drell-Yan processes with sufficiently intense beams of charged kaons on isoscalar targets. It is found that combinations of $K^+$ and $K^-$ Drell-Yan measurements on isoscalar nuclear targets would allow one to extract the kaon sea quark distributions. These cross sections are also sensitive to the strange valence quark distribution in the kaon, although one would need a significant increase over the presently available kaon fluxes in order to extract this quantity with sufficient accuracy.Comment: 9 pages plus 4 figures, on eps

Higher spin quaternion waves in the Klein-Gordon theory

Electromagnetic interactions are discussed in the context of the Klein-Gordon fermion equation. The Mott scattering amplitude is derived in leading order perturbation theory and the result of the Dirac theory is reproduced except for an overall factor of sixteen. The discrepancy is not resolved as the study points into another direction. The vertex structures involved in the scattering calculations indicate the relevance of a modified Klein-Gordon equation, which takes into account the number of polarization states of the considered quantum field. In this equation the d'Alembertian is acting on quaternion-like plane waves, which can be generalized to representations of arbitrary spin. The method provides the same relation between mass and spin that has been found previously by Majorana, Gelfand, and Yaglom in infinite spin theories

Sub-arcsecond imaging with the International LOFAR Telescope I. Foundational calibration strategy and pipeline

The International LOFAR Telescope is an interferometer with stations spread across Europe. With baselines of up to ~2000 km, LOFAR has the unique capability of achieving sub-arcsecond resolution at frequencies below 200 MHz. However, it is technically and logistically challenging to process LOFAR data at this resolution. To date only a handful of publications have exploited this capability. Here we present a calibration strategy that builds on previous high-resolution work with LOFAR. It is implemented in a pipeline using mostly dedicated LOFAR software tools and the same processing framework as the LOFAR Two-metre Sky Survey (LoTSS). We give an overview of the calibration strategy and discuss the special challenges inherent to enacting high-resolution imaging with LOFAR, and describe the pipeline, which is publicly available, in detail. We demonstrate the calibration strategy by using the pipeline on P205+55, a typical LoTSS pointing with an 8 h observation and 13 international stations. We perform in-field delay calibration, solution referencing to other calibrators in the field, self-calibration of these calibrators, and imaging of example directions of interest in the field. We find that for this specific field and these ionospheric conditions, dispersive delay solutions can be transferred between calibrators up to ~1.5° away, while phase solution transferral works well over ~1°. We also demonstrate a check of the astrometry and flux density scale with the in-field delay calibrator source. Imaging in 17 directions, we find the restoring beam is typically ~0.3′′ ×0.2′′ although this varies slightly over the entire 5 deg2 field of view. We find we can achieve ~80–300 μJy bm−1 image rms noise, which is dependent on the distance from the phase centre; typical values are ~90 μJy bm−1 for the 8 h observation with 48 MHz of bandwidth. Seventy percent of processed sources are detected, and from this we estimate that we should be able to image roughly 900 sources per LoTSS pointing. This equates to ~ 3 million sources in the northern sky, which LoTSS will entirely cover in the next several years. Future optimisation of the calibration strategy for efficient post-processing of LoTSS at high resolution makes this estimate a lower limit

LOFAR detections of low-frequency radio recombination lines towards Cassiopeia A

Cassiopeia A was observed using the low-band antennas of the LOw Frequency ARray (LOFAR) with high spectral resolution. This allowed a search for radio recombination lines (RRLs) along the line-of-sight to this source. Five carbon {$α$} RRLs were detected in absorption between 40 and 50 MHz with a signal-to-noise ratio of {gt}5 from two independent LOFAR data sets. The derived line velocities (v$_{LSR}$ ~{} - 50 km s$^{-1}$) and integrated optical depths (~{}13 s$^{-1}$) of the RRLs in our spectra, extracted over the whole supernova remnant, are consistent within each LOFAR data set and with those previously reported. For the first time, we are able to extract spectra against the brightest hotspot of the remnant at frequencies below 330 MHz. These spectra show significantly higher (15-80 percent) integrated optical depths, indicating that there is small-scale angular structure of the order of ~{}1 pc in the absorbing gas distribution over the face of the remnant. We also place an upper limit of 3 { imes} 10$^{-4}$ on the peak optical depths of hydrogen and helium RRLs. These results demonstrate that LOFAR has the desired spectral stability and sensitivity to study faint recombination lines in the decameter band