1,867 research outputs found
Transvaginal Ultrasonography in Ovarian Cancer Screening: Current Perspectives
Transvaginal ultrasonography (TVS) is an integral part of all major ovarian cancer screening trials. TVS is accurate in detecting abnormalities in ovarian volume and morphology, but is less reliable in differentiating benign from malignant ovarian tumors. When used as the only screening test, TVS is sensitive, but has a low positive predictive value. Therefore, serum biomarkers and tumor morphology indexing are used together with TVS to identify ovarian tumors at high risk for malignancy. This allows preoperative triage of high-risk cases to major cancer centers for therapy while decreasing unnecessary surgery for benign disease. Ovarian cancer screening has been associated with a decrease in stage at detection in most trials, thereby allowing treatment to be initiated when the disease is most curable
Uw mening over PraktijkKompas
De gemiddelde reactie is erg positief, maar er blijft voldoende ruimte voor verbetering
Fast two-layer two-photon imaging of neuronal cell populations using an electrically tunable lens
Functional two-photon Ca2+-imaging is a versatile tool to study the dynamics of neuronal populations in brain slices and living animals. However, population imaging is typically restricted to a single two-dimensional image plane. By introducing an electrically tunable lens into the excitation path of a two-photon microscope we were able to realize fast axial focus shifts within 15 ms. The maximum axial scan range was 0.7 mm employing a 40x NA0.8 water immersion objective, plenty for typically required ranges of 0.2–0.3 mm. By combining the axial scanning method with 2D acousto-optic frame scanning and random-access scanning, we measured neuronal population activity of about 40 neurons across two imaging planes separated by 40 μm and achieved scan rates up to 20–30 Hz. The method presented is easily applicable and allows upgrading of existing two-photon microscopes for fast 3D scanning
Развитие экстремального туризма в Крыму
Целью данной работы является на основе географического анализа факторов становления и особенностей развития экстремального туризма в Крыму разработать
рекомендации по усовершенствованию данной отрасли туристской деятельности для создания
привлекательного образа Крыма на международной арене
Robust nuclear lamina-based cell classification of aging and senescent cells
Changes in the shape of the nuclear lamina are exhibited in senescent cells, as well as in cells expressing mutations in lamina genes. To identify cells with defects in the nuclear lamina we developed an imaging method that quantifies the intensity and curvature of the nuclear lamina. We show that this method accurately describes changes in the nuclear lamina. Spatial changes in nuclear lamina coincide with redistribution of lamin A proteins and local reduction in protein mobility in senescent cell. We suggest that local accumulation of lamin A in the nuclear envelope leads to bending of the structure. A quantitative distinction of the nuclear lamina shape in cell populations was found between fresh and senescent cells, and between primary myoblasts from young and old donors. Moreover, with this method mutations in lamina genes were significantly distinct from cells with wild-type genes. We suggest that this method can be applied to identify abnormal cells during aging, in in vitro propagation, and in lamina disorders
Evidence for ubiquitous carbon grain destruction in hot protostellar envelopes
Earth is deficient in carbon and nitrogen by up to orders of
magnitude compared with the Sun. Destruction of (carbon- and nitrogen-rich)
refractory organics in the high-temperature planet forming regions could
explain this deficiency. Assuming a refractory cometary composition for these
grains, their destruction enhances nitrogen-containing oxygen-poor molecules in
the hot gas (K) after the initial formation and sublimation of
these molecules from oxygen-rich ices in the warm gas (K). Using
observations of high-mass protostars with ALMA, we find that
oxygen-containing molecules (CHOH and HNCO) systematically show no
enhancement in their hot component. In contrast, nitrogen-containing,
oxygen-poor molecules (CHCN and CHCN) systematically show an
enhancement of a factor in their hot component, pointing to
additional production of these molecules in the hot gas. Assuming only thermal
excitation conditions, we interpret these results as a signature of destruction
of refractory organics, consistent with the cometary composition. This
destruction implies a higher C/O and N/O in the hot gas than the warm gas,
while, the exact values of these ratios depend on the fraction of grains that
are effectively destroyed. This fraction can be found by future chemical models
that constrain C/O and N/O from the abundances of minor carbon, nitrogen and
oxygen carriers presented here.Comment: Accepted for publication in ApJ Letter
Carbon-grain sublimation: a new top-down component of protostellar chemistry
Earth's carbon deficit has been an outstanding problem in our understanding
of the formation of our Solar System. A possible solution would be the
sublimation of carbon grains at the so-called soot line (~300 K) early in the
planet-formation process. Here, we argue that the most likely signatures of
this process are an excess of hydrocarbons and nitriles inside the soot line,
and a higher excitation temperature for these molecules compared to
oxygen-bearing complex organics that desorb around the water snowline (~100 K).
Such characteristics have been reported in the literature, for example, in
Orion KL, although not uniformly, potentially due to differences in
observational settings and analysis methods of different studies or related to
the episodic nature of protostellar accretion. If this process is active, this
would mean that there is a heretofore unknown component to the carbon chemistry
during the protostellar phase that is acting from the top down - starting from
the destruction of larger species - instead of from the bottom up from atoms.
In the presence of such a top-down component, the origin of organic molecules
needs to be re-explored.Comment: Accepted for publication in ApJL. 14 pages, 2 figures, 1 table (4
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