6,335 research outputs found
Gamma rays from microquasars Cygnus X-1 and Cygnus X-3
Gamma-ray observations of microquasars at high and very-high energies can
provide valuable information of the acceleration processes inside the jets, the
jet-environment interaction and the disk-jet coupling. Two high-mass
microquasars have been deeply studied to shed light on these aspects: Cygnus
X-1 and Cygnus X-3. Both systems display the canonical hard and soft X-ray
spectral states of black hole transients, where the radiation is dominated by
non-thermal emission from the corona and jets and by thermal emission from the
disk, respectively. Here, we report on the detection of Cygnus X-1 above 60 MeV
using 7.5 yr of Pass8 Fermi-LAT data, correlated with the hard X-ray state. A
hint of orbital flux modulation was also found, as the source is only detected
in phases around the compact object superior conjunction. We conclude that the
high-energy gamma-ray emission from Cygnus X-1 is most likely associated with
jets and its detection allow us to constrain the production site. Moreover, we
include in the discussion the final results of a MAGIC long-term campaign on
Cygnus X-1 that reaches almost 100 hr of observations at different X-ray
states. On the other hand, during summer 2016, Cygnus X-3 underwent a flaring
activity period in radio and high-energy gamma rays, similar to the one that
led to its detection in the high-energy regime in 2009. MAGIC performed
comprehensive follow-up observations for a total of about 70 hr. We discuss our
results in a multi-wavelength context.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC
2017), Bexco, Busan, Korea (arXiv:1708.05153
Leveraging on Digital Signage Networks to Bring Connectivity IOT Devices
The number of Internet-connected devices exceeds the worldās population by more than three times and this figure is expected to be doubled within the next five years. The Internet of Things is a concept that describes this trend and outlines certain aspects of design and functionality that new devices should incorporate for a successful integration into the Internet. In this respect, Digital Signage networks traditionally used for audiovisual media, accomplish many of the characteristics of the Internet of Things devices: interoperability, mobility, scalability and ubiquity, both in terms of access and control of devices and regarding the information they generate. This paper raises the power to employ a proposed Digital Signage network as a substrate to connect other types of devices that can benefit from the advantages of this kind of networks. For that aim, the main problems for this integration are discussed, mainly those related to the bidirectional tunneling scheme used in the proposed Digital Signage solution. The effects of this tunneling approach are analyzed in scenarios with bandwidth constraints, and different solutions are proposed. Tunneling performance in mobility is improved, to increase the amount of Internet of Things devices and applications that can benefit from this type of network.
El nuĢmero de dispositivos conectados a Internet supera actualmente a la poblacioĢn mundial por maĢs de tres veces y se espera que esta cifra se duplique en los proĢximos cinco anĢos. El Internet de las Cosas es un concepto que describe esta tendencia y perfila ciertos aspectos de disenĢo y funcionalidad que los nuevos dispositivos deben incorporar para lograr una integracioĢn exitosa en Internet. En este sentido, las redes digital signage utilizadas tradicionalmente para los medios de comunicacioĢn audiovisual cumplen muchas de las caracteriĢsticas requeridas en el contexto del Internet de las Cosas: interoperabilidad, movilidad, escalabilidad y ubicuidad; relativas tanto al acceso y control de dispositivos como a la informacioĢn que estos generan. En este trabajo se plantea el poder de emplear la red digital signage propuesta como sustrato para poder conectar otros tipos de dispositivos para que asiĢ puedan aprovechar las ventajas de estas redes. Para ese fin, se discuten los principales problemas existentes en esta integracioĢn, prestando especial atencioĢn al esquema de tuĢnel bidireccional utilizado en la solucioĢn digital signage propuesta. Los efectos de este enfoque de tunelacioĢn se analizan en escenarios con limitaciones de ancho de banda y se proponen diferentes soluciones. Con ello se consigue mejorar el rendimiento del tuĢnel en movilidad, facilitando la integracioĢn de maĢs dispositivos al Internet de las Cosas al permitir que puedan integrarse en este tipo de redes
Room-temperature Operation of Low-voltage, Non-volatile, Compound-semiconductor Memory Cells
Whilst the different forms of conventional (charge-based) memories are well suited to their individual
roles in computers and other electronic devices, flaws in their properties mean that intensive research
into alternative, or emerging, memories continues. In particular, the goal of simultaneously achieving
the contradictory requirements of non-volatility and fast, low-voltage (low-energy) switching
has proved challenging. Here, we report an oxide-free, floating-gate memory cell based on III-V
semiconductor heterostructures with a junctionless channel and non-destructive read of the stored
data. Non-volatile data retention of at least 104 s in combination with switching at ā¤2.6 V is achieved
by use of the extraordinary 2.1 eV conduction band offsets of InAs/AlSb and a triple-barrier resonant
tunnelling structure. The combination of low-voltage operation and small capacitance implies intrinsic
switching energy per unit area that is 100 and 1000 times smaller than dynamic random access
memory and Flash respectively. The device may thus be considered as a new emerging memory with
considerable potential
RF plasma cleaning of optical surfaces: A study of cleaning rates on different carbon allotropes as a function of RF powers and distances
An extended study on an advanced method for the cleaning of carbon
contaminations on large optical surfaces using a remote inductively coupled low
pressure RF plasma source (GV10x downstream asher) is reported in this work.
Technical as well as scientific features of this scaled up cleaning process are
analyzed, such as the cleaning efficiency for different carbon allotropes
(amorphous and diamond-like carbon) as a function of feedstock gas composition,
RF power (ranging from 30 to 300W), and source-object distances (415 to 840
mm). The underlying physical phenomena for these functional dependences are
discussed.Comment: 16 pages, 9 figure
In the absence of ATPase activity, pre-RC formation is blocked prior to MCM2-7 hexamer dimerization
The origin recognition complex (ORC) of Saccharomyces cerevisiae binds origin DNA and cooperates with Cdc6 and Cdt1 to load the replicative helicase MCM2ā7 onto DNA. Helicase loading involves two MCM2ā7 hexamers that assemble into a double hexamer around double-stranded DNA. This reaction requires ORC and Cdc6 ATPase activity, but it is unknown how these proteins control MCM2ā7 double hexamer formation. We demonstrate that mutations in Cdc6 sensor-2 and Walker A motifs, which are predicted to affect ATP binding, influence the ORCāCdc6 interaction and MCM2ā7 recruitment. In contrast, a Cdc6 sensor-1 mutant affects MCM2ā7 loading and Cdt1 release, similar as a Cdc6 Walker B ATPase mutant. Moreover, we show that Orc1 ATP hydrolysis is not involved in helicase loading or in releasing ORC from loaded MCM2ā7. To determine whether Cdc6 regulates MCM2ā7 double hexamer formation, we analysed complex assembly. We discovered that inhibition of Cdc6 ATPase restricts MCM2ā7 association with origin DNA to a single hexamer, while active Cdc6 ATPase promotes recruitment of two MCM2ā7 hexamer to origin DNA. Our findings illustrate how conserved Cdc6 AAA+ motifs modulate MCM2ā7 recruitment, show that ATPase activity is required for MCM2ā7 hexamer dimerization and demonstrate that MCM2ā7 hexamers are recruited to origins in a consecutive process
Oral Ascorbic Acid and Alpha-Tocopherol to Reduce Behavioural Problems in Young Patients Affected of Fragile X Syndrome: A Randomized, Double-Blind, Placebo-Controlled Phase II Pilot Trial
Measurement of the Ds Lifetime
We report the results of a precise measurement of the Ds meson lifetime based
on 1662 +/- 56 fully reconstructed Ds -> phi pi decays, from the charm
hadroproduction experiment E791 at Fermilab. Using an unbinned maximum
likelihood fit, we measure the Ds lifetime to be 0.518 +/- 0.014 +/- 0.007 ps.
The ratio of the measured Ds lifetime to the world average D0 lifetime is 1.25
+/- 0.04. This result differs from unity by six standard deviations, indicating
significantly different lifetimes for the Ds and the D0.Comment: 12 pages, 3 figures, 2 table. LaTe
Search for the Flavor-Changing Neutral-Current Decays and
We report the results of a search for the flavor-changing neutral-current
decays and in
data from Fermilab charm hadroproduction experiment E791. No signal above
background is found, and we obtain upper limits on branching fractions,
and
, at the 90\% confidence
level.Comment: nine pages with figures; compressed, uuencoded postscrip
Experimental evidence for a light and broad scalar resonance in decay
From a sample of decay, we find
. Using a coherent amplitude analysis
to fit the Dalitz plot of this decays, we find strong evidence that a scalar
resonance of mass MeV/ and width MeV/ accounts for approximately half of all decays.Comment: 10 pages, 3 eps figure
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