5,264 research outputs found
Network Defense: The Attacks of Today and How Can We Improve?
The practices of Network Defense were analyzed in this research paper. The Internet has become a very dangerous place for computer systems and networks as an increasing number of malicious attacks are occurring each day. Attacks such as Phishing, Campaign Style Attacks, Zero Day Exploits, and Botnets are plaguing individuals and firms who are concerned for the protection of their data and systems. By utilizing a combination of defense systems including Firewalls, Intrusion Protection Systems, 802.1x, NAC, Antivirus, Antispyware and more, I have developed a comprehensive system which can be used as a model of Network Security. In conclusion there many firms that are not ready for Network Security in today’s computer world. With the question of economics needed to remediate the issue, there is the question on how secure are companies and individuals going to be
Superfluid-insulator transition in a periodically driven optical lattice
We demonstrate that the transition from a superfluid to a Mott insulator in
the Bose-Hubbard model can be induced by an oscillating force through an
effective renormalization of the tunneling matrix element. The mechanism
involves adiabatic following of Floquet states, and can be tested
experimentally with Bose-Einstein condensates in periodically driven optical
lattices. Its extension from small to very large systems yields nontrivial
information on the condensate dynamics.Comment: 4 pages, 4 figures, RevTe
The MX beamlines BL14.1-3 at BESSY II
The Macromolecular Crystallography (MX) group at the Helmholtz-Zentrum Berlin (HZB) is operating three state-of-the-art synchrotron beamlines for MX at BESSY II in Berlin (Heinemann et al., 2003; Mueller et al., 2012, 2015). The radiation source for all three beamlines BL14.1-3 is a superconducting 7T-wavelength shifter. Currently, the three beam lines are the most productive stations for MX in Germany, with about 250 PDB depositions per year and over 1500 PDB depositions in total (Status 10/2015). BL14.1 and BL14.2 are energy tuneable in the range 5.5-15.5 keV, while beam line BL14.3 is a fixed-energy side station operated at 13.8 keV. The HZB-MX beamlines are in regular user operation providing close to 200 beam days per year and about 600 user shifts to approximately 100 research groups across Europe. Additional user facilities include office space adjacent to the beam lines, a sample preparation laboratory, a biology laboratory (safety level 1) and high-end computing resources
Ground-state energy and depletions for a dilute binary Bose gas
When calculating the ground-state energy of a weakly interacting Bose gas
with the help of the customary contact pseudopotential, one meets an artifical
ultraviolet divergence which is caused by the incorrect treatment of the true
interparticle interactions at small distances. We argue that this problem can
be avoided by retaining the actual, momentum-dependent interaction matrix
elements, and use this insight for computing both the ground-state energy and
the depletions of a binary Bose gas mixture. Even when considering the
experimentally relevant case of equal masses of both species, the resulting
expressions are quite involved, and no straightforward generalizations of the
known single-species formulas. On the other hand, we demonstrate in detail how
these latter formulas are recovered from our two-species results in the limit
of vanishing interspecies interaction.Comment: 11 pages, Phys. Rev. A in pres
Fractional photon-assisted tunneling in an optical superlattice: large contribution to particle transfer
Fractional photon-assisted tunneling is investigated both analytically and
numerically for few interacting ultra-cold atoms in the double-wells of an
optical superlattice. This can be realized experimentally by adding periodic
shaking to an existing experimental setup [Phys. Rev. Lett. 101, 090404
(2008)]. Photon-assisted tunneling is visible in the particle transfer between
the wells of the individual double wells. In order to understand the physics of
the photon-assisted tunneling, an effective model based on the rotating wave
approximation is introduced. The validity of this effective approach is tested
for wide parameter ranges which are accessible to experiments in double-well
lattices. The effective model goes well beyond previous perturbation theory
approaches and is useful to investigate in particular the fractional
photon-assisted tunneling resonances. Analytic results on the level of the
experimentally realizable two-particle quantum dynamics show very good
agreement with the numerical solution of the time-dependent Schr\"odinger
equation. Far from being a small effect, both the one-half-photon and the
one-third-photon resonance are shown to have large effects on the particle
transfer.Comment: 9 pages, 11 png-figure
Cognitive Radio Networks: Realistic or Not?
A large volume of research has been conducted in the cognitive radio (CR)
area the last decade. However, the deployment of a commercial CR network is yet
to emerge. A large portion of the existing literature does not build on real
world scenarios, hence, neglecting various important interactions of the
research with commercial telecommunication networks. For instance, a lot of
attention has been paid to spectrum sensing as the front line functionality
that needs to be completed in an efficient and accurate manner to enable an
opportunistic CR network architecture. This is necessary to detect the
existence of spectrum holes without which no other procedure can be fulfilled.
However, simply sensing (cooperatively or not) the energy received from a
primary transmitter cannot enable correct dynamic spectrum access. For example,
the low strength of a primary transmitter's signal does not assure that there
will be no interference to a nearby primary receiver. In addition, the presence
of a primary transmitter's signal does not mean that CR network users cannot
access the spectrum since there might not be any primary receiver in the
vicinity. Despite the existing elegant and clever solutions to the DSA problem
no robust, implementable scheme has emerged. In this paper, we challenge the
basic premises of the proposed schemes. We further argue that addressing the
technical challenges we face in deploying robust CR networks can only be
achieved if we radically change the way we design their basic functionalities.
In support of our argument, we present a set of real-world scenarios, inspired
by realistic settings in commercial telecommunications networks, focusing on
spectrum sensing as a basic and critical functionality in the deployment of
CRs. We use these scenarios to show why existing DSA paradigms are not amenable
to realistic deployment in complex wireless environments.Comment: Work in progres
Achieving highly efficient gene transfer to the bladder by increasing the molecular weight of polymer-based nanoparticles
Short dwell-time and poor penetration of the bladder permeability barrier (BPB) are the main obstacles to intravesical treatments for bladder diseases, and is evidenced by the lack of such therapeutic options on the market. Herein, we demonstrate that by finely tuning the molecular weight of our cationic polymer mucoadhesive nanoparticles, we enhanced our gene transfer, leading to improved adherence and penetrance through the BPB in a safe and efficient manner. Specifically, increasing the polymer molecular weight from 45 kDa to 83 kDa enhanced luciferase plasmid transfer to the healthy murine bladder, leading to 1.35 ng/g luciferase protein expression in the urothelium and lamina propria regions. The relatively higher molecular weight polymer (83 kDa) did not induce morphologic changes or inflammatory responses in the bladder. This approach of altering polymer molecular weight for prolonging gene transfer residence time and deeper penetration through the BPB could be the basis for the design of future gene therapies for bladder diseases
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Cross-genetic determination of maternal and neonatal immune mediators during pregnancy.
BACKGROUND:The immune system plays a fundamental role in development during pregnancy and early life. Alterations in circulating maternal and neonatal immune mediators have been associated with pregnancy complications as well as susceptibility to autoimmune and neurodevelopmental conditions in later life. Evidence suggests that the immune system in adults not only responds to environmental stimulation but is also under strong genetic control. METHODS:This is the first genetic study of > 700 mother-infant pairs to analyse the circulating levels of 22 maternal mid-gestational serum-derived and 42 neonatal bloodspot-derived immune mediators (cytokines/chemokines) in the context of maternal and fetal genotype. We first estimated the maternal and fetal genome-wide SNP-based heritability (h2g) for each immune molecule and then performed genome-wide association studies (GWAS) to identify specific loci contributing to individual immune mediators. Finally, we assessed the relationship between genetic immune determinants and ASD outcome. RESULTS:We show maternal and neonatal cytokines/chemokines displaying genetic regulation using independent methodologies. We demonstrate that novel fetal loci for immune function independently affect the physiological levels of maternal immune mediators and vice versa. The cross-associated loci are in distinct genomic regions compared with individual-specific immune mediator loci. Finally, we observed an interaction between increased IL-8 levels at birth, autism spectrum disorder (ASD) status, and a specific maternal genotype. CONCLUSIONS:Our results suggest that maternal and fetal genetic variation influences the immune system during pregnancy and at birth via distinct mechanisms and that a better understanding of immune factor determinants in early development may shed light on risk factors for developmental disorders
ALMA Multi-line Imaging of the Nearby Starburst Galaxy NGC 253
We present spatially resolved (50 pc) imaging of molecular gas species
in the central kiloparsec of the nearby starburst galaxy NGC 253, based on
observations taken with the Atacama Large Millimeter/submillimeter Array
(ALMA). A total of 50 molecular lines are detected over a 13 GHz bandwidth
imaged in the 3 mm band. Unambiguous identifications are assigned for 27 lines.
Based on the measured high CO/CO isotopic line ratio (350), we
show that CO(1-0) has moderate optical depths. A comparison of the HCN
and HCO with their C-substituted isotopologues shows that the
HCN(1-0) and HCO(1-0) lines have optical depths at least comparable to
CO(1-0). HCN/HCO (and HCN/HNC) line ratios
provide tighter constraints on dense gas properties in this starburst. SiO has
elevated abundances across the nucleus. HNCO has the most distinctive
morphology of all the bright lines, with its global luminosity dominated by the
outer parts of the central region. The dramatic variation seen in the HNCO/SiO
line ratio suggests that some of the chemical signatures of shocked gas are
being erased in the presence of dominating central radiation fields (traced by
CH and CN). High density molecular gas tracers (including HCN, HCO,
and CN) are detected at the base of the molecular outflow. We also detect
hydrogen recombination lines that, like their counterparts,
show compact, centrally peaked morphologies, distinct from the molecular gas
tracers. A number of sulfur based species are mapped (CS, SO, NS, CS,
HCS and CHSH) and have morphologies similar to SiO.Comment: 20 pages, 10 figures, accepted to the Astrophysical Journa
Down-regulation of GP130 signaling sensitizes bladder cancer to cisplatin by impairing Ku70 DNA repair signaling and promoting apoptosis
Chemoresistance is one of the barriers for the development of bladder cancer treatments. Previously, we showed that glycoprotein-130 (GP130) is overexpressed in chemoresistant bladder cancer cells and that knocking down GP130 expression reduced cell viability. In our current work, we showed that down-regulation of GP130 sensitized bladder cancer cells to cisplatin-based chemotherapy by activating DNA repair signaling. We performed immunohistochemistry and demonstrated a positive correlation between the levels of Ku70, an initiator of canonical non-homologous end joining repair (c-NHEJ) and suppressor of apoptosis, and GP130 in human bladder cancer specimens. GP130 knockdown by SC144, a small molecule inhibitor, in combination with cisplatin, increased the number of DNA lesions, specifically DNA double-stranded breaks, with a subsequent increase in apoptosis and reduced cell viability. Furthermore, GP130 inhibition attenuated Ku70 expression in bladder and breast cancer cells as well as in transformed kidney cells. In addition, we fabricated a novel polymer-lipid hybrid delivery system to facilitate GP130 siRNA delivery that had a similar efficiency when compared with Lipofectamine, but induced less toxicity
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