963 research outputs found
Multi-protocol IoT network reconnaissance
Network reconnaissance is a core security functionality, which can be used to detect hidden unauthorized devices or to identify missing devices. Currently, there is a lack of network reconnaissance tools capable of discovering Internet of Things (IoT) devices across multiple protocols. To bridge this gap, we introduce IoT-Scan, an extensible IoT network reconnaissance tool. IoT - Scan is based on software-defined radio (SDR) technology, which allows for a flexible implementation of radio protocols. We propose passive, active, multi-channel, and multi-protocol scanning algorithms to speed up the discovery of devices with IoT-Scan. We implement the scanning algorithms and compare their performance with four popular IoT protocols: Zigbee, Bluetooth LE, Z-Wave, and LoRa. Through experiments with dozens of IoT devices, we demonstrate that our implementation experiences minimal packet losses, and achieves performance near a theoretical benchmark.CNS-1908087 - National Science Foundation; CCF-2006628 - National Science Foundation; ECCS-2128517 - National Science Foundation; CNS-1717858 - National Science FoundationAccepted manuscrip
DWSB in heterotic flux compactifications
We address the construction of non-supersymmetric vacua in heterotic
compactifications with intrinsic torsion and background fluxes. In particular,
we implement the approach of domain-wall supersymmetry breaking (DWSB)
previously developed in the context of type II flux compactifications. This
approach is based on considering backgrounds where probe NS5-branes wrapping
internal three-cycles and showing up as four-dimensional domain-walls do not
develop a BPS bound, while all the other BPS bounds characterizing the N=1
supersymmetric compactifications are preserved at tree-level. Via a scalar
potential analysis we provide the conditions for these backgrounds to solve the
ten-dimensional equations of motion including order \alpha' corrections. We
also consider backgrounds where some of the NS5-domain-walls develop a BPS
bound, show their relation to no-scale SUSY-breaking vacua and construct
explicit examples via elliptic fibrations. Finally, we consider backgrounds
with a non-trivial gaugino condensate and discuss their relation to
supersymmetric and non-supersymmetric vacua in the present context.Comment: 56 pages, 1 figur
The Transcription Factor SpoVG Is of Major Importance for Biofilm Formation of Staphylococcus epidermidis under In Vitro Conditions, but Dispensable for In Vivo Biofilm Formation
Staphylococcus epidermidis is a common cause of device related infections on which pathogens
form biofilms (i.e., multilayered cell populations embedded in an extracellular matrix). Here, we
report that the transcription factor SpoVG is essential for the capacity of S. epidermidis to form such
biofilms on artificial surfaces under in vitro conditions. Inactivation of spoVG in the polysaccharide
intercellular adhesin (PIA) producing S. epidermidis strain 1457 yielded a mutant that, unlike its
parental strain, failed to produce a clear biofilm in a microtiter plate-based static biofilm assay. A
decreased biofilm formation capacity was also observed when 1457 ∆spoVG cells were co-cultured
with polyurethane-based peripheral venous catheter fragments under dynamic conditions, while
the cis-complemented 1457 ∆spoVG::spoVG derivative formed biofilms comparable to the levels seen
with the wild-type. Transcriptional studies demonstrated that the deletion of spoVG significantly
altered the expression of the intercellular adhesion (ica) locus by upregulating the transcription of
the ica operon repressor icaR and down-regulating the transcription of icaADBC. Electrophoretic
mobility shift assays (EMSA) revealed an interaction between SpoVG and the icaA-icaR intergenic
region, suggesting SpoVG to promote biofilm formation of S. epidermidis by modulating ica expression.
However, when mice were challenged with the 1457 ∆spoVG mutant in a foreign body infection
model, only marginal differences in biomasses produced on the infected catheter fragments between
the mutant and the parental strain were observed. These findings suggest that SpoVG is critical for the
PIA-dependent biofilm formation of S. epidermis under in vitro conditions, but is largely dispensable
for biofilm formation of this skin commensal under in vivo conditions
"What's (the) Matter?", A Show on Elementary Particle Physics with 28 Demonstration Experiments
We present the screenplay of a physics show on particle physics, by the
Physikshow of Bonn University. The show is addressed at non-physicists aged 14+
and communicates basic concepts of elementary particle physics including the
discovery of the Higgs boson in an entertaining fashion. It is also
demonstrates a successful outreach activity heavily relying on the university
physics students. This paper is addressed at anybody interested in particle
physics and/or show physics. This paper is also addressed at fellow physicists
working in outreach, maybe the experiments and our choice of simple
explanations will be helpful. Furthermore, we are very interested in related
activities elsewhere, in particular also demonstration experiments relevant to
particle physics, as often little of this work is published.
Our show involves 28 live demonstration experiments. These are presented in
an extensive appendix, including photos and technical details. The show is set
up as a quest, where 2 students from Bonn with the aid of a caretaker travel
back in time to understand the fundamental nature of matter. They visit
Rutherford and Geiger in Manchester around 1911, who recount their famous
experiment on the nucleus and show how particle detectors work. They travel
forward in time to meet Lawrence at Berkeley around 1950, teaching them about
the how and why of accelerators. Next, they visit Wu at DESY, Hamburg, around
1980, who explains the strong force. They end up in the LHC tunnel at CERN,
Geneva, Switzerland in 2012. Two experimentalists tell them about colliders and
our heroes watch live as the Higgs boson is produced and decays. The show was
presented in English at Oxford University and University College London, as
well as Padua University and ICTP Trieste. It was 1st performed in German at
the Deutsche Museum, Bonn (5/'14). The show has eleven speaking parts and
involves in total 20 people.Comment: 113 pages, 88 figures. An up to date version of the paper with high
resolution pictures can be found at
http://www.th.physik.uni-bonn.de/People/dreiner/Downloads/. In v2 the
acknowledgements and a citation are correcte
BPS-like potential for compactifications of heterotic M-theory?
We analyze the possibility to rewrite the action of Horava-Witten theory in a
BPS-like form, which means that it is given as a sum of squares of the
supersymmetry conditions. To this end we compactify the theory on a seven
dimensional manifold of SU(3) structure and rewrite the scalar curvature of the
compactification manifold in terms of the SU(3) structure forms. This shows
that a BPS-like form cannot be obtained in general, but only for certain types
of compactifications.Comment: 31 pages, no figures, references added, typos correcte
Design of 280 GHz feedhorn-coupled TES arrays for the balloon-borne polarimeter SPIDER
We describe 280 GHz bolometric detector arrays that instrument the
balloon-borne polarimeter SPIDER. A primary science goal of SPIDER is to
measure the large-scale B-mode polarization of the cosmic microwave background
in search of the cosmic-inflation, gravitational-wave signature. 280 GHz
channels aid this science goal by constraining the level of B-mode
contamination from galactic dust emission. We present the focal plane unit
design, which consists of a 1616 array of conical, corrugated feedhorns
coupled to a monolithic detector array fabricated on a 150 mm diameter silicon
wafer. Detector arrays are capable of polarimetric sensing via waveguide
probe-coupling to a multiplexed array of transition-edge-sensor (TES)
bolometers. The SPIDER receiver has three focal plane units at 280 GHz, which
in total contains 765 spatial pixels and 1,530 polarization sensitive
bolometers. By fabrication and measurement of single feedhorns, we demonstrate
14.7 FHWM Gaussian-shaped beams with 1% ellipticity in a 30%
fractional bandwidth centered at 280 GHz. We present electromagnetic
simulations of the detection circuit, which show 94% band-averaged,
single-polarization coupling efficiency, 3% reflection and 3% radiative loss.
Lastly, we demonstrate a low thermal conductance bolometer, which is
well-described by a simple TES model and exhibits an electrical noise
equivalent power (NEP) = 2.6 10 W/,
consistent with the phonon noise prediction.Comment: Proceedings of SPIE Astronomical Telescopes + Instrumentation 201
Plant-RRBS, a bisulfite and next-generation sequencing-based methylome profiling method enriching for coverage of cytosine positions
Background: Cytosine methylation in plant genomes is important for the regulation of gene transcription and transposon activity. Genome-wide methylomes are studied upon mutation of the DNA methyltransferases, adaptation to environmental stresses or during development. However, from basic biology to breeding programs, there is a need to monitor multiple samples to determine transgenerational methylation inheritance or differential cytosine methylation. Methylome data obtained by sodium hydrogen sulfite (bisulfite)-conversion and next-generation sequencing (NGS) provide genome- wide information on cytosine methylation. However, a profiling method that detects cytosine methylation state dispersed over the genome would allow high-throughput analysis of multiple plant samples with distinct epigenetic signatures. We use specific restriction endonucleases to enrich for cytosine coverage in a bisulfite and NGS-based profiling method, which was compared to whole-genome bisulfite sequencing of the same plant material.
Methods: We established an effective methylome profiling method in plants, termed plant-reduced representation bisulfite sequencing (plant-RRBS), using optimized double restriction endonuclease digestion, fragment end repair, adapter ligation, followed by bisulfite conversion, PCR amplification and NGS. We report a performant laboratory protocol and a straightforward bioinformatics data analysis pipeline for plant-RRBS, applicable for any reference-sequenced plant species.
Results: As a proof of concept, methylome profiling was performed using an Oryza sativa ssp. indica pure breeding line and a derived epigenetically altered line (epiline). Plant-RRBS detects methylation levels at tens of millions of cytosine positions deduced from bisulfite conversion in multiple samples. To evaluate the method, the coverage of cytosine positions, the intra-line similarity and the differential cytosine methylation levels between the pure breeding line and the epiline were determined. Plant-RRBS reproducibly covers commonly up to one fourth of the cytosine positions in the rice genome when using MspI-DpnII within a group of five biological replicates of a line. The method predominantly detects cytosine methylation in putative promoter regions and not-annotated regions in rice.
Conclusions: Plant-RRBS offers high-throughput and broad, genome- dispersed methylation detection by effective read number generation obtained from reproducibly covered genome fractions using optimized endonuclease combinations, facilitating comparative analyses of multi-sample studies for cytosine methylation and transgenerational stability in experimental material and plant breeding populations
Dll1 Haploinsufficiency in Adult Mice Leads to a Complex Phenotype Affecting Metabolic and Immunological Processes
BACKGROUND: The Notch signaling pathway is an evolutionary conserved signal transduction pathway involved in embryonic patterning and regulation of cell fates during development and self-renewal. Recent studies have demonstrated that this pathway is integral to a complex system of interactions, involving as well other signal transduction pathways, and implicated in distinct human diseases. Delta-like 1 (Dll1) is one of the known ligands of the Notch receptors. The role of the Notch ligands is less well understood. Loss-of-function of Dll1 leads to embryonic lethality, but reduction of Delta-like 1 protein levels has not been studied in adult stage. METHODOLOGY/PRINCIPAL FINDINGS: Here we present the haploinsufficient phenotype of Dll1 and a missense mutant Dll1 allele (Dll1(C413Y)). Haploinsufficiency leads to a complex phenotype with several biological processes altered. These alterations reveal the importance of Dll1 mainly in metabolism, energy balance and in immunology. The animals are smaller, lighter, with altered fat to lean ratio and have increased blood pressure and a slight bradycardia. The animals have reduced cholesterol and triglyceride levels in blood. At the immunological level a subtle phenotype is observed due to the effect and fine-tuning of the signaling network at the different levels of differentiation, proliferation and function of lymphocytes. Moreover, the importance of the proteolytic regulation of the Notch signaling network emphasized. CONCLUSIONS/SIGNIFICANCE: In conclusion, slight alterations in one player of Notch signaling alter the entire organism, emphasizing the fine-tuning character of this pathway in a high number of processes
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