1,574 research outputs found
Examination of foramen tympanicum: an anatomical study using cone-beam computed tomography
Background: The foramen tympanicum (FT) is an osseous dehiscence of the temporal bone and usually closes by the age of 5 years. The foramen is located posteromedial to the temporomandibular joint and anteroinferior of the external auditory canal. The aim of this study is to define the prevalence, location and size of the foramen.
Materials and methods: We retrospectively examined 200 cone-beam computed tomography (CBCT) images (400 ears). We used a CBCT dental imaging system (GALILEOS, Sirona Dental Systems, Bensheim, Germany) working at 15–30 mA and 98 kV. We noted size and location (unilateral and bilateral) of the present FT.
Results: Foramen tympanicum was determined in 11.5% of 200 patients (they had FT at least on one side of the head). This was bilateral in 5 (2.5%) patients. Prevalence of the FT was significintly higher in females (8%) than in males (3.5%). FT was found more frequently on the left side (7.5%) than on the right side (4%). Mean axial diameter was 1.13 mm (range 0.23–4.43 mm), and mean sagittal diameter was 1.44 mm (range 0.22–3.99 mm).
Conclusions: Considering that FT was present in 11.75% of patients, radiologists and clinicians should be aware of the possible presence of this defect. It is known that this developmental dehiscence may cause herniation of temporomandibular joint, formation of salivary otorrhea, and spread of tumour or infection to the infratemporal fossa from external auditory canal. This study showed that CBCT may be preferred for imaging these conditions. (Folia Morphol 2018; 77, 2: 335–339
Randomly Charged Polymers, Random Walks, and Their Extremal Properties
Motivated by an investigation of ground state properties of randomly charged
polymers, we discuss the size distribution of the largest Q-segments (segments
with total charge Q) in such N-mers. Upon mapping the charge sequence to
one--dimensional random walks (RWs), this corresponds to finding the
probability for the largest segment with total displacement Q in an N-step RW
to have length L. Using analytical, exact enumeration, and Monte Carlo methods,
we reveal the complex structure of the probability distribution in the large N
limit. In particular, the size of the longest neutral segment has a
distribution with a square-root singularity at l=L/N=1, an essential
singularity at l=0, and a discontinuous derivative at l=1/2. The behavior near
l=1 is related to a another interesting RW problem which we call the "staircase
problem". We also discuss the generalized problem for d-dimensional RWs.Comment: 33 pages, 19 Postscript figures, RevTe
Vancomycin-resistant enterococci colonization in patients with hematological malignancies: screening and its cost-effectiveness
Background and objective: We evaluated the rates of vancomycin-resistant enterococci (VRE) colonization and VRE related bacteremia in patients with hematological malignancies in terms of routine screening culture and its cost-effectiveness.Materials and Methods: All patients of the hematology department who were older than 14 years of age and who developed at least one febrile neutropenia episode during chemotherapy for hematological cancers between November 2010 and November 2012 were evaluated retrospectively.Results: We retrospectively analyzed 282 febrile episodes in 126 neutropenic patients during a two-year study period. The study included 65 cases in the first study-year and 78 cases in the second study-year. The numbers of colonization days and colonized patient were 748 days of colonization in 29 patients (44%) in the first study-year and 547 colonization days in 21 patients (26%) in the second study-year, respectively. Routine screening culture for VRE cost 5082,7 (504 cultures) in the second study-year depending on the number of patients and their length of stay.Conclusion: In line with our study results, routine screening of hematological patients for VRE colonization is not costeffective. Routine surveillance culture for VRE should be considered with respect to the conditions of health care setting.Keywords: Hematological patients, febrile neutropenia, vancomycin-resistant enterococci, vancomycin-sensitive enterococci, bacteremia, colonization
Gutenberg Richter and Characteristic Earthquake Behavior in Simple Mean-Field Models of Heterogeneous Faults
The statistics of earthquakes in a heterogeneous fault zone is studied
analytically and numerically in the mean field version of a model for a
segmented fault system in a three-dimensional elastic solid. The studies focus
on the interplay between the roles of disorder, dynamical effects, and driving
mechanisms. A two-parameter phase diagram is found, spanned by the amplitude of
dynamical weakening (or ``overshoot'') effects (epsilon) and the normal
distance (L) of the driving forces from the fault. In general, small epsilon
and small L are found to produce Gutenberg-Richter type power law statistics
with an exponential cutoff, while large epsilon and large L lead to a
distribution of small events combined with characteristic system-size events.
In a certain parameter regime the behavior is bistable, with transitions back
and forth from one phase to the other on time scales determined by the fault
size and other model parameters. The implications for realistic earthquake
statistics are discussed.Comment: 21 pages, RevTex, 6 figures (ps, eps
Search of Axions from a Nuclear Power Reactor with a High-Purity Germanium Detector
A search of axions produced in nuclear transitions was performed at the
Kuo-Sheng Nuclear Power Station with a high-purity germanium detector of mass
1.06 kg at a distance of 28 m from the 2.9 GW reactor core. The expected
experimental signatures were mono-energetic lines produced by their Primakoff
or Compton conversions at the detector. Based on 459.0/96.3 days of Reactor
ON/OFF data, no evidence of axion emissions were observed and constraints on
the couplings \gagg and \gaee versus axion mass within the framework
of invisible axion models were placed. The KSVZ and DFSZ models can be excluded
for 10^4 eV < m_a < 10^6 ~eV. Model-independent constraints on \gagg \gv1 < 7.7
X 10^{-9} GeV^{-2} for m_{a} < 10^5 eV and \gaee \gv1 < 1.3 X 10^{-10} for
m_{a} < 10^6 eV at 90% confidence level were derived. This experimental
approach provides a unique probe for axion mass at the keV--MeV range not
accessible to the other techniques.Comment: 9 pages, 4 tables, 8 figures, V2: major expansion from V
Production and Decay of the Ge73-m Metastable State in a Low-Background Germanium Detector
The metastable states decay with a very characteristic signature
which allow them to be tagged event-by-event. Studies were performed using data
taken with a high-purity germanium detector in a low-background laboratory near
a nuclear power reactor core where \nuebar-flux was . The measured average and equilibrium production rates of
were and ,
respectively. The production channels were studied and identified. By studying
the difference in the production of between the reactor ON and OFF
spectra, the limiting sensitivities at the range of for the cross-sections of neutrino-induced nuclear
transitions were derived. The dominant background are due to -decays of
cosmic-ray induced Ga. The prospects of enhancing the sensitivities at
underground locations are discussed.Comment: 16 pages, 10 figure
Measurement of Neutrino-Electron Scattering Cross-Section with a CsI(Tl) Scintillating Crystal Array at the Kuo-Sheng Nuclear Power Reactor
The elastic scattering cross-section was measured with
a CsI(Tl) scintillating crystal array having a total mass of 187kg. The
detector was exposed to an average reactor flux of
at the Kuo-Sheng Nuclear Power
Station. The experimental design, conceptual merits, detector hardware, data
analysis and background understanding of the experiment are presented. Using
29882/7369 kg-days of Reactor ON/OFF data, the Standard Model(SM) electroweak
interaction was probed at the squared 4-momentum transfer range of . The ratio of experimental to SM cross-sections
of was measured. Constraints on
the electroweak parameters were placed, corresponding to a weak
mixing angle measurement of \s2tw = 0.251 \pm 0.031({\it stat}) \pm
0.024({\it sys}) . Destructive interference in the SM \nuebar -e process was
verified. Bounds on anomalous neutrino electromagnetic properties were placed:
neutrino magnetic moment at \mu_{\nuebar}< 2.2 \times 10^{-10} \mu_{\rm B}
and the neutrino charge radius at -2.1 \times 10^{-32} ~{\rm cm^{2}} <
\nuchrad < 3.3 \times 10^{-32} ~{\rm cm^{2}}, both at 90% confidence level.Comment: 18 Figures, 7 Tables; published version as V2 with minor revision
from V
MIR376A is a regulator of starvation-induced autophagy
Background: Autophagy is a vesicular trafficking process responsible for the degradation of long-lived, misfolded or abnormal proteins, as well as damaged or surplus organelles. Abnormalities of the autophagic activity may result in the accumulation of protein aggregates, organelle dysfunction, and autophagy disorders were associated with various diseases. Hence, mechanisms of autophagy regulation are under exploration.
Methods: Over-expression of hsa-miR-376a1 (shortly MIR376A) was performed to evaluate its effects on autophagy. Autophagy-related targets of the miRNA were predicted using Microcosm Targets and MIRanda bioinformatics tools and experimentally validated. Endogenous miRNA was blocked using antagomirs and the effects on target expression and autophagy were analyzed. Luciferase tests were performed to confirm that 3’ UTR sequences in target genes were functional. Differential expression of MIR376A and the related MIR376B was compared using TaqMan quantitative PCR.
Results: Here, we demonstrated that, a microRNA (miRNA) from the DlkI/Gtl2 gene cluster, MIR376A, played an important role in autophagy regulation. We showed that, amino acid and serum starvation-induced autophagy was blocked by MIR376A overexpression in MCF-7 and Huh-7 cells. MIR376A shared the same seed sequence and had overlapping targets with MIR376B, and similarly blocked the expression of key autophagy proteins ATG4C and BECN1 (Beclin 1). Indeed, 3’ UTR sequences in the mRNA of these autophagy proteins were responsive to MIR376A in luciferase assays. Antagomir tests showed that, endogenous MIR376A was participating to the control of ATG4C and BECN1 transcript and protein levels. Moreover, blockage of endogenous MIR376A accelerated starvation-induced autophagic activity. Interestingly, MIR376A and MIR376B levels were increased with different kinetics in response to starvation stress and tissue-specific level differences were also observed, pointing out to an overlapping but miRNA-specific biological role.
Conclusions: Our findings underline the importance of miRNAs encoded by the DlkI/Gtl2 gene cluster in stress-response control mechanisms, and introduce MIR376A as a new regulator of autophagy
Neutrino-electron scattering in noncommutative space
Neutral particles can couple with the gauge field in the adjoint
representation at the tree level if the space-time coordinates are
noncommutative (NC). Considering neutrino-photon coupling in the NC QED
framework, we obtain the differential cross section of neutrino-electron
scattering. Similar to the magnetic moment effect, one of the NC terms is
proportional to , where is the electron recoil energy.
Therefore, this scattering provides a chance to achieve a stringent bound on
the NC scale in low energy by improving the sensitivity to the smaller electron
recoil energy.Comment: 12 pages, 2 figure
Anisotropic Scaling in Threshold Critical Dynamics of Driven Directed Lines
The dynamical critical behavior of a single directed line driven in a random
medium near the depinning threshold is studied both analytically (by
renormalization group) and numerically, in the context of a Flux Line in a
Type-II superconductor with a bulk current . In the absence of
transverse fluctuations, the system reduces to recently studied models of
interface depinning. In most cases, the presence of transverse fluctuations are
found not to influence the critical exponents that describe longitudinal
correlations. For a manifold with internal dimensions,
longitudinal fluctuations in an isotropic medium are described by a roughness
exponent to all orders in , and a
dynamical exponent . Transverse
fluctuations have a distinct and smaller roughness exponent
for an isotropic medium. Furthermore, their
relaxation is much slower, characterized by a dynamical exponent
, where is the
correlation length exponent. The predicted exponents agree well with numerical
results for a flux line in three dimensions. As in the case of interface
depinning models, anisotropy leads to additional universality classes. A
nonzero Hall angle, which has no analogue in the interface models, also affects
the critical behavior.Comment: 26 pages, 8 Postscript figures packed together with RevTeX 3.0
manuscript using uufiles, uses multicol.sty and epsf.sty, e-mail
[email protected] in case of problem
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