Hawking radiation from dynamical horizons

In completely local settings, we establish that a dynamically evolving black hole horizon can be assigned a Hawking temperature. Moreover, we calculate the Hawking flux and show that the radius of the horizon shrinks.Comment: 5 Page

New Records of Thecacineta cothurnioides and Trematosoma rotunda (Ciliophora, Suctorea) as epibionts on nematodes from the Indian Ocean

This article deals with the report of two suctorian ciliates species viz. Thecacineta cothurnioides Collin, 1909 and Trematosoma rotunda (Allgén, 1952 ) as epibionts on Tricoma sp. and Pseudochromadora sp. (Nematoda) respectively from Ratnagiri, west coast of India, Arabian Sea (Indian Ocean). Redescription of two species with distribution and nomenclatural notes are given. Both species are recorded here first time from Indian coast and the Indian Ocean. Genus Tricoma Cobb, 1894 is also recorded here first time as a host of Th. cothurnioides

Report of epibiont Thecacineta calix (Ciliophora: Suctorea) on deep sea Desmodora (Nematoda) from the Andaman Sea, Indian Ocean

Suctorian epibionts Thecacineta calix attached on the cuticle of nematodes Desmodora sphaerica and D. pontica are reported here from the deep sea hexactinellid sponge Pheronema sp. from the Andaman Sea (Indian Ocean). The epibiont T. calix is reported here for first time from the Andaman Sea

An overview of Suctorian ciliates (Ciliophora, Suctorea) as epibionts of halacarid mites (Acari, Halacaridae)

Scant information is available regarding the prevalence and distribution of suctorian ciliates on halacarid mites. However, using this limited information and data from our laboratory on the systematics, biology, ecology and distribution of suctorian ciliates that are epibionts of halacarid mites, we redescribed four suctorian species: Limnoricus ceter (Jankowski), Praethecacineta halacari (Schulz), Thecacineta calix (Schroder) and Acineta sulcata Dons. We also recognized Lissacineta allgeni Jankowski and Thecacineta allgeni (Jankowski) as synonyms of Praethecacineta halacari (Schluz), and Thecacineta laophontis Jankowski and Paracineta moebiusi Kahl as synonyms of Thecacineta calix (Schroder). Many suctorians have been reported, but not properly identified in the halacarid literature. So, we have attempted to identify those suctorians to species level. Lastly, the interactions between the suctorians and their hosts are also discussed and Praethecacineta halacari is also reported for the first time from the Indian coast

New records of Praethecacineta halacari (Schulz) (Suctorea: Ciliophora) from Taiwan, Tanzania and Canada

The present study reports on a range extension of the suctorian species Praethecacineta halacari to the region of He-Ping-Dao, north-east of Taiwan (West Pacific Ocean), Matemwe, the east coast of Unguja, Zanzibar, Tanzania (West Indian Ocean) and Nova Scotia, Canada (West Atlantic Ocean). Praethecacineta halacari is reported here for the first time from Taiwan, Tanzania and Canada. Earlier records include the Caspian Sea, Western Australia, Brazil, India, and various coastal sites in Europe

Lifshitz transition from valence fluctuations in YbAl3

In Kondo lattice systems with mixed valence, such as YbAl3, interactions between localized electrons in a partially filled f shell and delocalized conduction electrons can lead to fluctuations between two different valence configurations with changing temperature or pressure. The impact of this change on the momentum-space electronic structure and Fermi surface topology is essential for understanding their emergent properties, but has remained enigmatic due to a lack of appropriate experimental probes. Here by employing a combination of molecular beam epitaxy (MBE) and in situ angle-resolved photoemission spectroscopy (ARPES) we show that valence fluctuations can lead to dramatic changes in the Fermi surface topology, even resulting in a Lifshitz transition. As the temperature is lowered, a small electron pocket in YbAl3 becomes completely unoccupied while the low-energy ytterbium (Yb) 4f states become increasingly itinerant, acquiring additional spectral weight, longer lifetimes, and well-defined dispersions. Our work presents the first unified picture of how local valence fluctuations connect to momentum space concepts including band filling and Fermi surface topology in the longstanding problem of mixed-valence systems.Comment: 18 pages, 11 figure

Lensing of Fast Radio Bursts by Plasma Structures in Host Galaxies

Plasma lenses in the host galaxies of fast radio bursts (FRBs) can strongly modulate FRB amplitudes for a wide range of distances, including the $\sim$ Gpc distance of the repeater FRB121102. To produce caustics, the lens' dispersion-measure depth (${\rm DM}_{\ell}$), scale size ($a$), and distance from the source ($d_{\rm sl}$) must satisfy ${\rm DM}_{\ell} d_{\rm sl} / a^2 \gtrsim 0.65~ {\rm pc^2 \ AU^{-2} \ cm^{-3}}$. Caustics produce strong magnifications ($\lesssim 10^2$) on short time scales ($\sim$ hours to days and perhaps shorter) along with narrow, epoch dependent spectral peaks (0.1 to 1~GHz). However, strong suppression also occurs in long-duration ($\sim$ months) troughs. For geometries that produce multiple images, the resulting burst components will arrive differentially by $< 1~\mu$s to tens of ms and they will show different apparent dispersion measures, $\delta{\rm DM}_{\rm apparent} \sim 1$ pc cm$^{-3}$. Arrival time perturbations may mask any underlying periodicity with period $\lesssim 1$ s. When arrival times differ by less than the burst width, interference effects in dynamic spectra are expected. Strong lensing requires source sizes smaller than $({\rm Fresnel~scale)^2} / a$, which can be satisfied by compact objects such as neutron star magnetospheres but not by AGNs. Much of the phenomenology of the repeating fast radio burst source FRB121102 is similar to lensing effects. The overall picture can be tested by obtaining wideband spectra of bursts (from $<1$ to 10 GHz and possibly higher), which can also be used to characterize the plasma environment near FRB sources. A rich variety of phenomena is expected from an ensemble of lenses near the FRB source. We discuss constraints on densities, magnetic fields, and locations of plasma lenses related to requirements for lensing to occur.Comment: 11 pages, 7 figures, submitted to the Astrophysical Journa

Accelerating Universe as Window for Extra Dimensions

Homogeneous cosmological solutions are obtained in five dimensional space time assuming equations of state $p = k\rho$ and $p_{5}= \gamma\rho$ where p is the isotropic 3 - pressure and $p_{5}$, that for the fifth dimension. Using different values for the constants k and $\gamma$ many known solutions are rediscovered. Further the current acceleration of the universe has led us to investigate higher dimensional gravity theory, which is able to explain acceleration from a theoretical view point without the need of introducing dark energy by hand. We argue that the terms containing higher dimensional metric coefficients produce an extra negative pressure that apparently drives an acceleration of the 3D space, tempting us to suggest that the accelerating universe seems to act as a window to the existence of extra spatial dimensions. Interestingly the 5D matter field remains regular while the \emph{effective} negative pressure is responsible for the inflation. Relaxing the assumptions of two equations of state we also present a class of solutions which provide early deceleration followed by a late acceleration in a unified manner. Interesting to point out that in this case our cosmology apparently mimics the well known quintessence scenario fuelled by a generalised Chaplygin-type of fluid where a smooth transition from a dust dominated model to a de Sitter like one takes place.Comment: 20 pages,3 figure