2,631 research outputs found
Sleep Complaints Affecting School Performance at Different Educational Levels
The clear association between reports of sleep disturbance and poor school performance has been documented for sleepy adolescents. This study extends that research to students outside the adolescent age grouping in an associated school setting (98 middle school students, 67 high school students, and 64 college students). Reported restless legs and periodic limb movements are significantly associated with lower GPA's in junior high students. Consistent with previous studies, daytime sleepiness was the sleep variable most likely to negatively affects high school students. Sleep onset and maintenance insomnia were the reported sleep variables significantly correlated with poorer school performance in college students. This study indicates that different sleep disorder variables negatively affect performance at different age and educational levels
Gas gun shock experiments with single-pulse x-ray phase contrast imaging and diffraction at the Advanced Photon Source
The highly transient nature of shock loading and pronounced microstructure
effects on dynamic materials response call for {\it in situ}, temporally and
spatially resolved, x-ray-based diagnostics. Third-generation synchrotron x-ray
sources are advantageous for x-ray phase contrast imaging (PCI) and diffraction
under dynamic loading, due to their high photon energy, high photon fluxes,
high coherency, and high pulse repetition rates. The feasibility of bulk-scale
gas gun shock experiments with dynamic x-ray PCI and diffraction measurements
was investigated at the beamline 32ID-B of the Advanced Photon Source. The
x-ray beam characteristics, experimental setup, x-ray diagnostics, and static
and dynamic test results are described. We demonstrate ultrafast, multiframe,
single-pulse PCI measurements with unprecedented temporal (100 ps) and
spatial (2 m) resolutions for bulk-scale shock experiments, as well
as single-pulse dynamic Laue diffraction. The results not only substantiate the
potential of synchrotron-based experiments for addressing a variety of shock
physics problems, but also allow us to identify the technical challenges
related to image detection, x-ray source, and dynamic loading
Reduction of energy cost of magnetization switching in a biaxial nanoparticle by use of internal dynamics
A solution to energy-efficient magnetization switching in a nanoparticle with
biaxial anisotropy is presented. Optimal control paths minimizing the energy
cost of magnetization reversal are calculated numerically as functions of the
switching time and materials properties, and used to derive energy-efficient
switching pulses of external magnetic field. Hard-axis anisotropy reduces the
minimum energy cost of magnetization switching due to the internal torque in
the desired switching direction. Analytical estimates quantifying this effect
are obtained based on the perturbation theory. The optimal switching time
providing a tradeoff between fast switching and energy efficiency is obtained.
The energy cost of switching and the energy barrier between the stable states
can be controlled independently in a biaxial nanomagnet. This provides a
solution to the dilemma between energy-efficient writability and good thermal
stability of magnetic memory elements.Comment: 13 pages, 10 figure
190 MeV Proton-Induced Fission
This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit
Zastosowanie nieinwazyjnej metody NIR-T/BSS (Near Infra-Red Transillumination-Back Scattering) do monitorowania zmian ukrwienia mózgu w chirurgii naczyń szyjnych
Wstęp. Z roku na rok zwiększa się liczba zabiegów wykonywanych na tętnicach
szyjnych. Dotychczas stosowane metody kontroli zmian ukrwienia mózgu wydają się
niewystarczające. Szczególnie dotkliwy jest brak możliwości monitorowania podczas
zabiegu operacyjnego.
Cel pracy. Wykazanie przydatności nowo opracowanej metody transluminacji
w bliskiej podczerwieni (NIR-T/BSS) do monitorowania zmian ukrwienia mózgu podczas
zabiegu operacyjnego endarterektomii, oceny jego skuteczności, jak również do
wspomagania diagnostyki przed zabiegiem.
Materiał i metody. Badaniem objęto 50
chorych ze zwężeniem tętnicy szyjnej, u których wykonano zabieg endarterektomii.
Wyniki. Zastosowanie metody NIR-T/BSS pozwoliło obiektywnie ocenić krążenie
oboczne, wybrać kolejność stron w przypadku zabiegów obustronnych przy takim samym
stopniu zwężenia, określonym metodą opartą na efekcie Dopplera, monitorować zmiany
ukrwienia mózgu podczas zabiegu operacyjnego oraz ocenić poprawę ukrwienia mózgu
po zabiegu.
Wnioski. Wstępna ocena wyników uzyskanych za pomocą metody NIR-T/BSS pozwala
uznać ją za bardzo przydatną metodę nieinwazyjnego monitorowania zmian ukrwienia
mózgu. Technika ta jest łatwa do zastosowania w warunkach operacyjnych, charakteryzuje
się wysoką czułością, a otrzymane wyniki korelują z wynikami uzyskanymi innymi
metodami (np. Dopplera) oraz z procedurą zabiegu. Przedstawione zapisy mają charakter
jakościowy.Background. A steady rising trend is observed in the number of carotid
surgeries performed. Methods of monitoring of changes in cerebral blood supply
used so far, prove inadequate and insufficient. Of special importance and value
would be availability of such monitoring during carotid surgery.
Aim of the study. The objective of the current study was evaluation of
the applicability and usefulness of a newly devised non-invasive method of Near
Infra-Red Transillumination/Backscattering Sounding (NIR-T/BSS) for monitoring
of changes in cerebral blood supply in the course of carotid endarterectomy and
for assessment of the effectiveness of the surgery, as well as a supplementary
diagnostic tool prior to surgical treatment.
Material and methods. NIR-T/BSS recordings were made in 50 patients with
recognised carotid stenosis, in whom surgical treatment with carotid endarterectomy
was performed.
Results. Application of the NIR-T/BSS method enabled: A. objective
assessment of the collateral circulation, B. selection of the sequence of sides
to be operated on in cases of equal bilateral carotid stenosis, as determined
with Doppler ultrasound, C. monitoring of the changes in cerebral blood supply
during the surgery, and D. post-operative evaluation of the beneficial effect
of the surgery.
Conclusions. The early results obtained with the NIR-T/BSS method provide
arguments to believe that this method will soon be recognised as highly useful
modality in monitoring of the changes in cerebral blood supply. The technique
is characterised by high simplicity of use in intra-operative conditions, high
sensitivity and congruence of the obtained results with those collected with other
methods, as well as with the logic of the physiological reactions. The presented
NIR-T/BSS recordings provide qualitative and not quantitative arguments
Uterine NK cells are critical in shaping DC immunogenic functions compatible with pregnancy progression.
Dendritic cell (DC) and natural killer (NK) cell interactions are important for the regulation of innate and adaptive immunity, but their relevance during early pregnancy remains elusive. Using two different strategies to manipulate the frequency of NK cells and DC during gestation, we investigated their relative impact on the decidualization process and on angiogenic responses that characterize murine implantation. Manipulation of the frequency of NK cells, DC or both lead to a defective decidual response characterized by decreased proliferation and differentiation of stromal cells. Whereas no detrimental effects were evident upon expansion of DC, NK cell ablation in such expanded DC mice severely compromised decidual development and led to early pregnancy loss. Pregnancy failure in these mice was associated with an unbalanced production of anti-angiogenic signals and most notably, with increased expression of genes related to inflammation and immunogenic activation of DC. Thus, NK cells appear to play an important role counteracting potential anomalies raised by DC expansion and overactivity in the decidua, becoming critical for normal pregnancy progression
EBT2 Dosimetry of X-rays produced by the electron beam from PFMA-3, a Plasma Focus for medical applications
The electron beam emitted from the back of Plasma Focus devices is being
studied as a radiation source for IORT (IntraOperative Radiation Therapy)
applications. A Plasma Focus device is being developed to this aim, to be
utilized as an X-ray source. The electron beam is driven to impinge on 50
{\mu}m brass foil, where conversion X-rays are generated. Measurements with
gafchromic film are performed to analyse the attenuation of the X-rays beam and
to predict the dose given to the culture cell in radiobiological experiments to
follow.Comment: 10 pages, 14 figure
Entorse de la cheville chez le jeune sportif [Ankle sprain in youth athlete]
Lateral ankle sprain is the most frequent musculoskeletal injury in the young athlete. Myths, dogma and common belief are regularly encountered when discussing this injury, for which the scientific literature does not prevail yet. In the youth, the growing skeleton further influences the diagnosis and therapeutic processes, as well as the healing potential. For the athlete, a fast recovery and return to sports without recurrence are a priority. In this specific context, an integrated management of the ankle sprain in the young athlete must be based on an adequate diagnosis, a sound knowledge of pediatrics pitfalls and peer-reviewed physiotherapy recommendations and consensus statements
Virtual Top-Quark Effects on the H->bb-bar Decay at Next-to-Leading Order in QCD
By means of a heavy-top-quark effective Lagrangian, we calculate the
three-loop corrections of O(alpha_s^2 G_F M_t^2) to the H->bb-bar partial decay
width of the standard-model Higgs boson with intermediate mass M_H<<2M_t. We
take advantage of a soft-Higgs theorem to construct the relevant coefficient
functions. We present our result both in the MS-bar and on-shell schemes of
mass renormalization. The MS-bar formulation turns out to be favourable with
regard to the convergence behaviour. We also test a recent idea concerning the
naive non-abelianization of QCD.Comment: 8 pages (Latex), 5 figures (Postscript
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