Automated simulation of areal bone mineral density assessment in the distal radius from high-resolution peripheral quantitative computed tomography

SummaryAn automated image processing method is presented for simulating areal bone mineral density measures using high-resolution peripheral quantitative computed tomography (HR-pQCT) in the ultra-distal radius. The accuracy of the method is validated against clinical dual X-ray absorptiometry (DXA). This technique represents a useful reference to gauge the utility of novel 3D quantification methods applied to HR-pQCT in multi-center clinical studies and potentially negates the need for separate forearm DXA measurements.IntroductionOsteoporotic status is primarily assessed by measuring areal bone mineral density (aBMD) using 2D dual X-ray absorptiometry (DXA). However, this technique does not sufficiently explain bone strength and fracture risk. High-resolution peripheral quantitative computed tomography (HR-pQCT) has been introduced as a method to quantify 3D bone microstructure and biomechanics. In this study, an automated method is proposed to simulate aBMD measures from HR-pQCT distal radius images.MethodsA total of 117 subject scans were retrospectively analyzed from two clinical bone quality studies. The distal radius was imaged by HR-pQCT and DXA on one of two devices (Hologic or Lunar). Areal BMD was calculated by simulation from HR-pQCT images (aBMD(sim)) and by standard DXA analysis (aBMD(dxa)).ResultsThe reproducibility of the simulation technique was 1.1% (root mean-squared coefficient of variation). HR-pQCT-based aBMD(sim) correlated strongly to aBMD(dxa) (Hologic: R (2) = 0.82, Lunar: R (2) = 0.87), though aBMD(sim) underestimated aBMD(dxa) for both DXA devices (p < 0.0001). Finally, aBMD(sim) predicted aBMD at the proximal femur and lumbar spine with equal power compared to aBMD(dxa).ConclusionThe results demonstrate that aBMD can be simulated from HR-pQCT images of the distal radius. This approach has the potential to serve as a surrogate forearm aBMD measure for clinical HR-pQCT studies when axial bone mineral density values are not required

RNA secondary structure design

We consider the inverse-folding problem for RNA secondary structures: for a given (pseudo-knot-free) secondary structure find a sequence that has that structure as its ground state. If such a sequence exists, the structure is called designable. We implemented a branch-and-bound algorithm that is able to do an exhaustive search within the sequence space, i.e., gives an exact answer whether such a sequence exists. The bound required by the branch-and-bound algorithm are calculated by a dynamic programming algorithm. We consider different alphabet sizes and an ensemble of random structures, which we want to design. We find that for two letters almost none of these structures are designable. The designability improves for the three-letter case, but still a significant fraction of structures is undesignable. This changes when we look at the natural four-letter case with two pairs of complementary bases: undesignable structures are the exception, although they still exist. Finally, we also study the relation between designability and the algorithmic complexity of the branch-and-bound algorithm. Within the ensemble of structures, a high average degree of undesignability is correlated to a long time to prove that a given structure is (un-)designable. In the four-letter case, where the designability is high everywhere, the algorithmic complexity is highest in the region of naturally occurring RNA.Comment: 11 pages, 10 figure

Chemical Defense of an Asian Snake Reflects Local Availability of Toxic Prey and Hatchling Diet

Species that sequester toxins from prey for their own defense against predators may exhibit population-level variation in their chemical arsenal that reflects the availability of chemically defended prey in their habitat. Rhabdophis tigrinus is an Asian snake that possesses defensive glands in the skin of its neck (nuchal glands\u27), which typically contain toxic bufadienolide steroids that the snakes sequester from consumed toads. In this study, we compared the chemistry of the nuchal gland fluid of R.tigrinus from toad-rich and toad-free islands in Japan and determined the effect of diet on the nuchal gland constituents. Our findings demonstrate that captive-hatched juveniles from toad-rich Ishima Island that had not been fed toads possess defensive bufadienolides in their nuchal glands, presumably due to maternal provisioning of these sequestered compounds. Wild-caught juveniles from Ishima possess large quantities of bufadienolides, which could result from a combination of maternal provisioning and sequestration of these defensive compounds from consumed toads. Interestingly, juvenile females from Ishima possess larger quantities of bufadienolides than do juvenile males, whereas a small sample of field-collected snakes suggests that adult males contain larger quantities of bufadienolides than do adult females. Captive-born hatchlings from Kinkasan Island lack bufadienolides in their nuchal glands, reflecting the absence of toads on that island, but they can sequester bufadienolides by feeding on toads (Bufo japonicus) in captivity. The presence of large quantities of bufadienolides in the nuchal glands of R.tigrinus from Ishima may reduce the risk of predation by providing an effective chemical defense, whereas snakes on Kinkasan may experience increased predation due to the lack of defensive compounds in their nuchal glands

Kraus representation in the presence of initial correlations

We examine the validity of the Kraus representation in the presence of initial correlations and show that it is assured only when a joint dynamics is locally unitary.Comment: REVTeX4, 12 page

The potential therapeutic role of lymph node resection in epithelial ovarian cancer: a study of 13 918 patients

The aim of the study is to determine the role of lymphadenectomy in advanced epithelial ovarian cancer. The data were obtained from the Surveillance, Epidemiology and End Results (SEER) program reported between 1988 and 2001. Kaplan–Meier estimates and Cox proportional hazards regression models were used for analysis. Of 13 918 women with stage III–IV epithelial ovarian cancer (median age: 64 years), 87.9% were Caucasian, 5.6% African Americans, and 4.4% Asians. A total of 4260 (30.6%) underwent lymph node dissections with a median number of six nodes reported. For all patients, a more extensive lymph node dissection (0, 1, 2–5, 6–10, 11–20, and >20 nodes) was associated with an improved 5-year disease-specific survival of 26.1, 35.2, 42.6, 48.4, 47.5, and 47.8%, respectively (P<0.001). Of the stage IIIC patients with nodal metastases, the extent of nodal resection (1, 2–5, 6–10, 11–20, and >20 nodes) was associated with improved survivals of 36.9, 45.0, 47.8, 48.7, and 51.1%, respectively (P=0.023). On multivariate analysis, the extent of lymph node dissection and number of positive nodes were significant independent prognosticators after adjusting for age, year at diagnosis, stage, and grade of disease. The extent of lymphadenectomy is associated with an improved disease-specific survival of women with advanced epithelial ovarian cancer

Cuticular wax coverage and its transpiration barrier properties in Quercus coccifera L. leaves: does the environment matter?

Plants prevent uncontrolled water loss by synthesizing, depositing and maintaining a hydrophobic layer over their primary aerial organs-the plant cuticle. Quercus coccifera L. can plastically respond to environmental conditions at the cuticular level. When exposed to hot summer conditions with high vapour-pressure deficit (VPD) and intense solar radiation (Mediterranean atmospheric conditions; MED), this plant species accumulates leaf cuticular waxes even over the stomata, thereby decreasing transpirational water loss. However, under mild summer conditions with moderate VPD and regular solar radiation (temperate atmospheric conditions; TEM), this effect is sharply reduced. Despite the ecophysiological importance of the cuticular waxes of Q. coccifera, the wax composition and its contribution to avoiding uncontrolled dehydration remain unknown. Thus, we determined several leaf traits for plants exposed to both MED and TEM conditions. Further, we qualitatively and quantitatively investigated the cuticular lipid composition by gas chromatography. Finally, we measured the minimum leaf conductance (gmin) as an indicator of the efficacy of the cuticular transpiration barrier. The MED leaves were smaller, stiffer and contained a higher load of cuticular lipids than TEM leaves. The amounts of leaf cutin and cuticular waxes of MED plants were 1.4 times and 2.6 times higher than that found for TEM plants, respectively. In detail, MED plants produced higher amounts of all compound classes of cuticular waxes, except for the equivalence of alkanoic acids. Although MED leaves contained higher cutin and cuticular wax loads, the gmin was not different between the two habitats. Our findings suggest that the qualitative accumulation of equivalent cuticular waxes might compensate for the higher wax amount of MED plants, thereby contributing equally to the efficacy of the cuticular transpirational barrier of Q. coccifera. In conclusion, we showed that atmospheric conditions profoundly affect the cuticular lipid composition of Q. coccifera leaves, but do not alter its transpiration barrier properties

Cuticular wax coverage and its transpiration barrier properties in Quercus coccifera L. leaves: does the environment matter?

Plants prevent uncontrolled water loss by synthesizing, depositing and maintaining a hydrophobic layer over their primary aerial organs-the plant cuticle. Quercus coccifera L. can plastically respond to environmental conditions at the cuticular level. When exposed to hot summer conditions with high vapour-pressure deficit (VPD) and intense solar radiation (Mediterranean atmospheric conditions; MED), this plant species accumulates leaf cuticular waxes even over the stomata, thereby decreasing transpirational water loss. However, under mild summer conditions with moderate VPD and regular solar radiation (temperate atmospheric conditions; TEM), this effect is sharply reduced. Despite the ecophysiological importance of the cuticular waxes of Q. coccifera, the wax composition and its contribution to avoiding uncontrolled dehydration remain unknown. Thus, we determined several leaf traits for plants exposed to both MED and TEM conditions. Further, we qualitatively and quantitatively investigated the cuticular lipid composition by gas chromatography. Finally, we measured the minimum leaf conductance (gmin) as an indicator of the efficacy of the cuticular transpiration barrier. The MED leaves were smaller, stiffer and contained a higher load of cuticular lipids than TEM leaves. The amounts of leaf cutin and cuticular waxes of MED plants were 1.4 times and 2.6 times higher than that found for TEM plants, respectively. In detail, MED plants produced higher amounts of all compound classes of cuticular waxes, except for the equivalence of alkanoic acids. Although MED leaves contained higher cutin and cuticular wax loads, the gmin was not different between the two habitats. Our findings suggest that the qualitative accumulation of equivalent cuticular waxes might compensate for the higher wax amount of MED plants, thereby contributing equally to the efficacy of the cuticular transpirational barrier of Q. coccifera. In conclusion, we showed that atmospheric conditions profoundly affect the cuticular lipid composition of Q. coccifera leaves, but do not alter its transpiration barrier properties

Experimental Study of Inconel 718 Surface Treatment by Edge Robotic Deburring with Force Control

We present the results of investigations into the application of robotics for deburring and chamfering to a predefined geometric quality. The robotic application was used for a part of the manufacturing process of an aircraft engine detail.Представлены результаты исследования по оценке использования робототехники для снятия заусенец и фасок с жестким геометрическим допуском. Робототехнические средства использовались для части процесса изготовления деталей авиационных двигателей

Making sense of social pretense: The effect of the dyad, sex and language ability in a large observational study of children’s behaviors in a social pretend play context

Pretend play with peers is purportedly an important driver of social development in the preschool period, however, fundamental questions regarding the features of children’s pretend play with a peer, and the effect of the dyad for pretend play, have been overlooked. The current study undertook detailed behavioral coding of social pretend play in 134 pairs of 5-year-old children (54% boys) in order to address three main aims: (i) describe the duration and proportion of children engaging in key social pretend play behaviors, namely, calls for attention, negotiation (comprising role assignment and joint proposals) and enactment of pretend play, (ii) examine the effect of the dyad in influencing the occurrence of different social pretend play behaviors, and (iii) assess the independent and combined effect of individual child characteristics (i.e., language ability and sex) that may influence social pretend play behaviors beyond the influence of the dyad. Results demonstrated the overwhelming effect of the dyad in shaping children’s social pretend play behaviors, with language ability and sex explaining relatively little of the total variability in play behaviors. Results are discussed considering the contribution that this type of study can make to theories of associations between children’s social development and social pretend play.LEGO Foundatio

Influence of the detector's temperature on the quantum Zeno effect

In this paper we study the quantum Zeno effect using the irreversible model of the measurement. The detector is modeled as a harmonic oscillator interacting with the environment. The oscillator is subjected to the force, proportional to the energy of the measured system. We use the Lindblad-type master equation to model the interaction with the environment. The influence of the detector's temperature on the quantum Zeno effect is obtained. It is shown that the quantum Zeno effect becomes stronger (the jump probability decreases) when the detector's temperature increases