Focusing versus defocusing properties of truly naked black holes

We study the properties of the congruence of null geodesics propagating near the so-called truly naked horizons (TNH) - objects having finite Kretschmann scalar but with diverging tidal acceleration for freely falling observers. The expansion of outgoing rays near the future horizon always tends to vanish for the non-extremal case but may be non-zero for the distorted (ultra)extremal one. It tends to diverge for the ingoing ones if the the null energy condition (NEC) is satisfied in the vicinity of the horizon outside. However, it also tends to zero for NEC violating cases except the remote horizons. We also discuss the validity of test particle approximation for TNHs and find the sufficient condition for backreaction remaining small.Comment: 16 pages. To appear in IJMP

Atmospheric stability effects on aerosol structure and stratification

This paper essentially addresses the structure and stratification of the nocturnal boundary layer (NBL) derived from the vertical profile measurements of aerosol concentration made with a computer-controlled Argon ion lidar system at the Indian Institue of Tropical Meteorology (IITM), Pune, India. Companions are made between the lidar observations during clear night-sky conditions and concurrent aerometric observations carried out on some selected experimental days. The results show multiple stratified aerosol layer structures in the nocturnal lower atmosphere, which drift either upward or downward depending on atmospheric stability conditions prevailing at different altitudes. The normalized aerosol concentration gradient (NCG) profiles indicate the variations in the nocturnal mixing depth from 200 to 426 m and that in the stable layer height from 325 to 725 m during the period of observations. The importance of such observations in the context of monitoring and/or assesment of airborne particulate pollutants over the urban environments associated with non-uniform terrain is discussed

Anomalous frequency and intensity scaling of collective and local modes in a coupled spin tetrahedron system

We report on the magnetic excitation spectrum of the coupled spin tetrahedral system Cu$_{2}$Te$_{2}$O$_{5}$Cl$_{2}$ using Raman scattering on single crystals. The transition to an ordered state at T$_{N}^{Cl}$=18.2 K evidenced from thermodynamic data leads to the evolution of distinct low-energy magnetic excitations superimposed by a broad maximum. These modes are ascribed to magnons with different degree of localization and a two-magnon continuum. Two of the modes develop a substantial energy shift with decreasing temperature similar to the order parameter of other Neel ordered systems. The other two modes show only a negligible temperature dependence and dissolve above the ordering temperature in a continuum of excitations at finite energies. These observations point to a delicate interplay of magnetic inter- and intra-tetrahedra degrees of freedom and an importance of singlet fluctuations in describing a spin dynamics.Comment: 7pages, 6figures, 1tabl

Extra-hepatic fascioliasis with peritoneal malignancy tumor feature

Fascioliasis is a zoonose parasitic disease caused by Fasciola hepatica and Fasciola gigantica and is widespread in most regions of the world. Ectopic fascioliasis usually caused by juvenile Fasciola spp., but in recent years a few cases of tissue-embedded ova have been reported from different endemic areas. A 79-year-old Iranian man resident in Eird-e-Mousa village from Ardabil Province, north-west of Iran, complained with abdominal pain, nausea, and intestinal obstruction symptoms referred to Ardabil Fatemi hospital. In laparotomy multiple intestinal masses with peritoneal seeding resembling of a malignant lesion were seen. After appendectomy and peritoneal mass biopsy with numerous intraperitoneal adenopathy, paraffin embedded blocks were prepared from each tissues. A blood sample was taken from the patient 5 months later for serological diagnosis. Histopathological examination of sections showed fibrofatty stroma with dense mixed inflammatory cells infiltration and fibrosis in peritoneal masses. Large numbers of ova of Fasciola spp. were noted with typical circumscribed granulomas. Despite of anti-fasciola treatment, IHA test for detecting anti F. hepatica antibodies was positive 5 months after surgery with a titer of 1/128. Due to multiple clinical manifestation of extra-hepatic fascioliasis, its differential diagnosis from intraperitoneal tumors or other similar diseases should be considered