1,421 research outputs found
Quantum teleportation through time-shifted AdS wormholes
Based on the work of Gao-Jafferis-Wall and Maldacena-Stanford-Yang, we
observe that the time-shifted thermofield states of two entangled CFTs can be
made traversable by an appropriate coupling of the two CFTs, or alternatively
by the application of a modified quantum teleportation protocol. This provides
evidence for the smoothness of the horizon for a large class of entangled
states related to the thermofield by time-translations. The smoothness of these
states has some relevance for the firewall paradox and the proposal that some
observables in quantum gravity may be state-dependent. We notice that quantum
teleportation through these entangled states could be used in a laboratory
setup to implement a time-machine, which allows the observer to travel far in
the future.Comment: 18 page
The discovery of a type II quasar at z= 1.65 with integral-field spectroscopy
In this Letter we report the serendipitous discovery of a genuine type II quasar at z= 1.65 using integral-field data from the Visual Multi-Object Spectrograph (VIMOS) on the Very Large Telescope (VLT). This is the first discovery of a type II quasar at z > 1 from optical data alone. J094531-242831, hereafter J0945-2428, exhibits strong narrow (v < 1500 km s-1) emission lines, has a resolved host galaxy, and is undetected to a radio flux density limit of S5 GHz= 0.15 mJy (3Ï) . All of these characteristics lead us to believe that J0945-2428 is a bona fide type II quasar. The luminosity of the narrow emission lines in this object suggest that the intrinsic power of the central engine is similar to that found in powerful radio galaxies, indicative of a similarly large supermassive black hole of ⌠3 Ă 108 Mâ (assuming that it is accreting at its Eddington limit). However, from near-infrared imaging observations we find that the old stellar population in the host galaxy has a luminosity of ⌠0.2 Lâ, mildly inconsistent with the correlation between black hole mass and bulge luminosity found locally, although the uncertainty in the black hole mass estimate is large.
This discovery highlights the power that integral-field units have in discovering hidden populations of objects, particularly the sought-after type II quasars, which are invoked to explain the hard X-ray background. As such, future large integral-field surveys could open up a new window on the obscured accretion activity in the Universe
A reliable cluster detection technique using photometric redshifts: introducing the 2TecX algorithm
We present a new cluster detection algorithm designed for finding
high-redshift clusters using optical/infrared imaging data. The algorithm has
two main characteristics. First, it utilises each galaxy's full redshift
probability function, instead of an estimate of the photometric redshift based
on the peak of the probability function and an associated Gaussian error.
Second, it identifies cluster candidates through cross-checking the results of
two substantially different selection techniques (the name 2TecX representing
the cross-check of the two techniques). These are adaptations of the Voronoi
Tesselations and Friends-Of-Friends methods. Monte-Carlo simulations of mock
catalogues show that cross-checking the cluster candidates found by the two
techniques significantly reduces the detection of spurious sources.
Furthermore, we examine the selection effects and relative strengths and
weaknesses of either method. The simulations also allow us to fine-tune the
algorithm's parameters, and define completeness and mass limit as a function of
redshift. We demonstrate that the algorithm isolates high-redshift clusters at
a high level of efficiency and low contamination.Comment: 13 Pages, 17 figures, accepted for publication in MNRA
Only reasoned action? An interorganizational study of energy-saving behaviors in office buildings
Substantial energy savings can be achieved by reducing energy use in office buildings. The reported study used a Theory of Planned Behavior (TPB) model extended with perceived habit to explain office energy-saving behaviors. One aim was to examine if organizational contextual variability independently predicted office energy-saving behaviors over and above TPB variables and self-reported habit. Another aim was to examine the relative predictive value of TPB variables and habit for energy-saving behaviors between organizational contexts. Survey data on energy-saving behaviors, TPB variables, and habit and number of office mates were collected from office workers of four organizations in the Netherlands. The results indicate that intention was the strongest direct predictor of the behaviors printing smaller and not printing e-mails, whereas habit was the strongest predictor of the behaviors switching off lights and switching off monitors. Of the social-cognitive factors, attitude was the strongest predictor of intentions overall. The effect of perceived norm varied widely between behaviors and subgroups. Number of office mates had a direct, unmediated effect on the behavior switching off lights and a mediated effect via attitude and perceived control. The effect of organizational contextual variability on behavior was entirely mediated through the psychosocial factors for the two âprinting behaviorsâ, but only partially for the two âswitching behaviorsâ. The relative predictive value of habit and intention differed between organizations. The findings suggest that organizational contextual variability has unconscious influences on some office energy-saving behaviors. Interventions should take variation in the relative importance of cognitive factors and habit between behaviors, and to a lesser extent between organizational contexts, into account
Bioprinted gut-on-a-chip to mimic the small intestinal mucosa
Treballs Finals de Grau d'Enginyeria BiomĂšdica. Facultat de Medicina i CiĂšncies de la Salut. Universitat de Barcelona. Curs: 2020-2021. Directores: MarĂa GarcĂa DĂaz & NĂșria Torras AndrĂ©s. Tutora: Elena MartĂnez FraizOrgan-on-a-chip (OoC) is an emerging technology which combines microfluidics with cell culture
to create platforms that replicate human organs. These predictive models are used to understand
human physiology and to predict responses to medical treatments. Being the small intestine the
largest interface between the environment and the human organism and one of the most important
organs involved in drug metabolism, there is an increasing interest from researchers and the
pharmaceutical industry for reliable in vitro intestine models. However, currently available gut-ona-
chip devices that replicate the complex microenvironment found in the in vivo tissue are scarce,
limiting their translational capabilities to clinical outcomes. Therefore, in this work we aim to develop
a reproducible gut-on-a-chip device that mimics the 3D architecture and cell heterogeneity of the
small intestinal mucosa. SLA 3D bioprinting will be used to fabricate cell-encapsulating GelMAPEGDA
hydrogels that support the formation of an epithelial monolayer on top, to replicate the two
compartments of the intestinal mucosa; the lamina propria and the intestinal epithelial barrier. The
hydrogels contain fibroblasts and immune cells, which play a key role in maintaining the intestinal
mucosa integrity and homeostasis. These scaffolds will be then incorporated into PDMS
microfluidic chips to create the final biomimetic system. Although further improvements are needed,
this gut-on-a-chip, obtained using precise and fast fabrication techniques, might be a useful tool for
drug development and human physiology studies
THE TAXONOMIC STATUS OF THE WYOMING TOAD, BUFO BAXTERI PORTER
The population of toads in southeastern Wyoming named Bufo hemiophrys baxteri by Porter in 1968 is presumed to be extinct in nature, except perhaps for released, captive-bred specimens. It is sufficiently distinct in several respects, and sufficiently isolated geographically from its nearest rela- tive, B. h. hemiophrys, that it should be regarded as a distinct species, forming a superspecies group with B. hemiophrys
THE LECTOTYPE AND TYPE LOCALITY OF CANDOIA CARINATA (REPTILIA, SERPENTES)
The lectotype of Boa carinata Schneider, 1801, has been rediscovered and is now ZMFK35503, having been transferred in 1977 from the Göttingen Museum, its original location. Its typelocality has not been reported previously, but is indicated as âAmboinaâ on a label with the lectotype.The specimen is redescribed and fi gured, and conforms with expectations for material from the vicinityof the type locality. A brief history of Schneider and of the syntypes of Boa carinata, now Candoiacarinata, is reviewed
Persistent Memory File Systems:A Survey
Persistent Memory (PM) is non-volatile byte-addressable memory that offers read and write latencies in the order of magnitude smaller than flash storage, such as SSDs. This survey discusses how file systems address the most prominent challenges in the implementation of file systems for Persistent Memory. First, we discuss how the properties of Persistent Memory change file system design. Second, we discuss work that aims to optimize small file I/O and the associated meta-data resolution. Third, we address how existing Persistent Memory file systems achieve (meta) data persistence and consistency
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