41 research outputs found
Very High Energy gamma-rays from electron/positron Pair Halos
In this paper we study the formation of giant electrons-positron pair halos
around the powerful high energy extragalactic sources. We investigate the
dependence of radiation of pair halos, in particular the spectral and angular
distributions on the energy spectrum of the primary gamma-rays, the redshift of
the source, and the flux of the extragalactic background light.Comment: 17 pages, 17 figures, published in Volume No. 18, Issue No. 06 of
"International Journal Of Modern Physics D
Characterization of Bacillus species exhibiting strong proteolytic activity isolated from Thua Nao
In this study, two bacilli strains, namely TN51 and TN69, previously isolated from Thua Nao, a Thai traditional fermented soybean, were studied in terms of their phenotypic and biochemical properties. Initially, both strains were subjected to morphological determination and a series of biochemical tests. Both were Gram-positive, endosporeforming bacilli. Based on 16S rRNA gene sequence analysis, the identities of strains TN51 and TN69 were confirmed as Bacillus subtilis and B. cereus, respectively. In addition, these two strains were also assessed for their antibiogram profiles. It was found that both strains were susceptible to chloramphenicol, erythromycin, kanamycin, tetracycline, and vancomycin and resistant to ampicillin and intermediately susceptible to bacitracin
EGMF Constraints from Simultaneous GeV-TeV Observations of Blazars
Attenuation of the TeV gamma-ray flux from distant blazars through pair
production with extragalactic background light leads to the development of
electromagnetic cascades and subsequent, lower energy, GeV secondary gamma-ray
emission. Due to the deflection of VHE cascade electrons by extragalactic
magnetic fields (EGMF), the spectral shape of this arriving cascade gamma-ray
emission is dependent on the strength of the EGMF. Thus, the spectral shape of
the GeV-TeV emission from blazars has the potential to probe the EGMF strength
along the line of sight to the object. We investigate constraints on the EGMF
derived from observations of blazars for which TeV observations simultaneous
with those by the Fermi telescope were reported. We study the dependence of the
EGMF bound on the hidden assumptions it rests upon. We select blazar objects
for which simultaneous Fermi/LAT GeV and Veritas, MAGIC or HESS TeV emission
have been published. We model the development of electromagnetic cascades along
the gamma-ray beams from these sources using Monte Carlo simulations, including
the calculation of the temporal delay incurred by cascade photons, relative to
the light propagation time of direct gamma-rays from the source. Constraints on
EGMF could be derived from the simultaneous GeV-TeV data on the blazars RGB
J0710+591, 1ES 0229+200, and 1ES 1218+304. The measured source flux level in
the GeV band is lower than the expected cascade component calculated under the
assumption of zero EGMF. Assuming that the reason for the suppression of the
cascade component is the extended nature of the cascade emission, we find that
B>10^{-15} G (assuming EGMF correlation length of ~1 Mpc) is consistent with
the data. Alternatively, the assumption that the suppression of the cascade
emission is caused by the time delay of the cascade photons the data are
consistent with B>10^{-17} G for the same correlation length.Comment: 9 pages, 9 figure
Determination of volatile components in fermented soybean prepared by a co-culture of Bacillus subtilis and Rhizopus oligosporus
Fermented soybeans are traditional foods widely consumed in many countries (i.e., Natto in Japan, Jang in Korea, Kinema in India, Douichi in China, and Thua Nao in Thailand). In this study, an attempt was made with an expectation to improve the fermentation process using a co-culture of Bacillus subtilis and Rhizopus oligosporus. Initially, the raw soybeans were washed, sterilized by autoclaving, and inoculated with two inocula; for this, three different ratios between B. subtilis and R. oligosporus used were 100:0, 50:50, and 0:100. The fermentation was then carried out at 30°C for 3 days. The volatile compounds in the non-fermented and the fermented soybean products were determined by gas chromatography/ mass spectrometry (GC/MS) and extracted using a solid phase microextraction (SPME) technique. In total, 165 compounds were identified in the non-fermented and the fermented soybean products. For the non-fermented products, the predominant volatile compounds were alcohols (25.81%), aldehydes (13.64%), acids and esters (7.57%), furans (6.13%) and ketones (0.88%). In contrast, the major volatiles compounds presented in the fermented soybeans were as follows: i) The treatment of 100:0 consisted of acids and esters (35.89%), alcohols (14.55%), aldehydes (8.72%), ketones (4.97%), pyrazines (4.87%), and furans (4.22%); ii) 50:50 comprised of acids and esters (55.62%), alcohols (16.22%), aldehydes (7.80%), pyrazine (3.65%), ketones (2.55%), furans (1.67%), and aromatic compounds (1.46%); and iii) 0:100 included acids and esters (66.50%), alcohols (15.44%), aldehydes (2.59%), ketones (2.72%), furans (1.89%), aromatic compounds (1.80%), pyrazines (1.35%), and sulphur containing compounds (0.24%) respectively
Multigene Phylogeny Reveals Haploanthostomella elaeidis gen. et sp. nov. and Familial Replacement of Endocalyx (Xylariales, Sordariomycetes, Ascomycota)
During our investigation of palm fungi in Thailand, two interesting taxa from Elaeis guineensis and Metroxylon sagu (Arecaceae) were collected. Based on phylogenetic analyses of a combined dataset of ITS, LSU, rpb2, and tub2 nucleotide sequences as well as unique morphological characteristics, we introduce the new genus Haploanthostomella within Xylariales, and a new species Endocalyx metroxyli. Additionally, in our study, the genus Endocalyx is transferred to the family Cainiaceae based on its brown conidia and molecular phylogenetic evidence