Using reserves for computation optimization to improve the integration of rapidly oscillating functions

We present a theory of evaluating integrals of rapidly oscillating functions in various classes of subintegral functions with the use of a mesh information operator on subintegral functions. The theory allows us to derive and prove optimal (with respect to accuracy and (or) performance) and nearly optimal quadrature formulas and to test their quality against well-known and proposed numerical integration algorithms and to determine their efficiency domains. A technique is proposed to determine the optimal parameters of computational algorithms that obtain the ε-solution of the problem.     

Optimal integration of rapidly oscillating functions in the class W 2,L,N with the use of different information operators

The problem of computing integrals of rapidly oscillating differentiable functions using various information operators is considered. Quadrature formulas of optimal accuracy are derived and optimal estimates are obtained.     

Composition of negative air ions as a function of ion age and selected trace gases: Mass- and mobility distribution

In order to explore an additional window to look into the mechanisms behind atmospheric ion and particle formation, an advanced method, which combines the study of ageing of air ions by both mobility and mass spectrometry is developed and examined. The technique behind this method can produce new air ions and trace their evolution within the age interval from a few tenths of a second up to about 20 s. We measure the mobility spectra from 2.37 down to 0.0013 cm² V^?1 s^?1 and the mass spectra of these ions up to m/z 2000. The results demonstrate the ability of the method to trace the temporal evolution of the ions. The composition of negative air ions at an age of about 1 s is clearly different from that at about 20 s, contrarily to certain former results according to which the small ion evolution should mainly terminate within about a second. We investigate how variations in humidity and the elevated concentrations of iodine and diethylamine (DEA) modify the composition of the negative air ions. The concentrations of DEA and iodine are above their common values in the air, but also in these cases the observed trends should be applicable to the atmosphere. All the vapours investigated in this study modify the ion composition in quite a specific way. Most prominent transformations are induced by iodine, which transforms the mass spectrum of cluster ions into few dominant peaks at m/z 381 and 635. In mobility spectrum, it generates a large number of new heavy ions with the sizes of 4?40 nm, the heavy ions in turn decrease the concentration of cluster ions due to ion–aerosol attachment. The peaks at m/z 381 and 635 can be assigned to ions I^?(I₂) and I^?(I₂)₂, respectively. At an enhanced concentration of diethylamine vapour (DEA), the new ions NO₃^?(HNO₃)(DEA) seem very plausible to explain the appearance of the peak at m/z 198 in the mass-spectrum. DEA evokes a multimodal mobility spectrum with modes at about 1.75, 10 and 20 nm. Both the DEA and iodine generate the changes in the size distribution of aerosol particles, which can be associated with a new particle formation. The experiments with enhanced water vapour concentrations revealed a new peak at m/z 250, which could be assigned to HCO₃^?(HNO₃)₃ ions.     

Bias dependent NO2 sensitivity of SnO2 thin films at room temperature

Amorphous granular SnO₂ thin films were investigated from a standpoint of an NO₂ gas sensor working at room temperature. The films were deposited using pulsed laser deposition method with substrate at room temperature and ～90 nm thick SnO₂ films with amorphous structure were obtained as a result. SnO₂ films deposited on Pt electrode substrates formed a sensor structure that showed response I_air/I_gas to 4 ppm NO₂ up to ～8000. I–V characteristics of the sensor structure were described by the power law dependence, whereas the power indexes were different for measurements in pure air and in the presence of NO₂. As a result, the sensor response was highly dependent on bias voltage between the sensor electrodes. It was demonstrated that the nonlinear electrical characteristics and bias dependent gas sensitivity were the inherent properties of thin films and the contacts were ohmic.     

Appearance of airway absorption and exudation tracers in guinea pig tracheobronchial lymph nodes

This study examines the fate of extravasated plasma in inflammatory stimulus-challenged large tracheobronchial airways of ketamine-xylazine-anesthetized guinea pigs. Entry of plasma tracers into the airway lumen was determined by a validated noninjurious airway lavage technique. Removal by airway lymphatics was assessed by tracheobronchial lymph node levels of plasma tracers. Mucosal challenges with histamine (5 nmol), bradykinin (5 nmol), capsaicin (0.4 nmol), or allergen (ovalbumin, 3 pmol) increased the appearance of a plasma tracer (131I-labeled albumin previously injected intravenously) in the airway lumen within 10 min (10-20 times control; P < 0.001), whereas the contractile agent carbachol (8 nmol) was without exudative effect. The mediators were without effect, and capsaicin and allergen only slightly increased the lymph node level of plasma exudation tracer (1.5 times control; P < 0.05). Hence, removal via the lymphatic route of plasma macromolecules may be negligible in the acute and postacute phases of an airway exudation response. Experiments were also carried out with luminally applied macromolecular tracers. These were absorbed from the mucosal surface into the circulation, but a small portion was also transported to the lymph nodes, demonstrating the interconnections between the mucosa and the sampled nodes. Only capsaicin produced an increased node level of absorption tracer. Immunohistochemistry showed that the tracheobronchial tissue and lymph nodes are endowed with nerve fibers containing substance P, the release of which may have mediated lymph transport, vascular, and exudative effects of capsaicin in the present studies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Multiproject–multicenter evaluation of automatic brain tumor classification by magnetic resonance spectroscopy

Justification  Automatic brain tumor classification by MRS has been under development for more than a decade. Nonetheless, to our knowledge, there are no published evaluations of predictive models with unseen cases that are subsequently acquired in different centers. The multicenter eTUMOUR project (2004–2009), which builds upon previous expertise from the INTERPRET project (2000–2002) has allowed such an evaluation to take place. Materials and Methods  A total of 253 pairwise classifiers for glioblastoma, meningioma, metastasis, and low-grade glial diagnosis were inferred based on 211 SV short TE INTERPRET MR spectra obtained at 1.5 T (PRESS or STEAM, 20–32 ms) and automatically pre-processed. Afterwards, the classifiers were tested with 97 spectra, which were subsequently compiled during eTUMOUR. Results  In our results based on subsequently acquired spectra, accuracies of around 90% were achieved for most of the pairwise discrimination problems. The exception was for the glioblastoma versus metastasis discrimination, which was below 78%. A more clear definition of metastases may be obtained by other approaches, such as MRSI + MRI. Conclusions  The prediction of the tumor type of in-vivo MRS is possible using classifiers developed from previously acquired data, in different hospitals with different instrumentation under the same acquisition protocols. This methodology may find application for assisting in the diagnosis of new brain tumor cases and for the quality control of multicenter MRS databases.     

Human TRMT112-Methyltransferase Network Consists of Seven Partners Interacting with a Common Co-Factor

Methylation is an essential epigenetic modification mainly catalysed by S-Adenosyl methionine-dependent methyltransferases (MTases). Several MTases require a cofactor for their metabolic stability and enzymatic activity. TRMT112 is a small evolutionary conserved protein that acts as a co-factor and activator for different MTases involved in rRNA, tRNA and protein methylation. Using a SILAC screen, we pulled down seven methyltransferases—N6AMT1, WBSCR22, METTL5, ALKBH8, THUMPD2, THUMPD3 and TRMT11—as interaction partners of TRMT112. We showed that TRMT112 stabilises all seven MTases in cells. TRMT112 and MTases exhibit a strong mutual feedback loop when expressed together in cells. TRMT112 interacts with its partners in a similar way; however, single amino acid mutations on the surface of TRMT112 reveal several differences as well. In summary, mammalian TRMT112 can be considered as a central “hub” protein that regulates the activity of at least seven methyltransferases.     

Chemisorption and Dehydration of Ethanol on Silica: Effect of Temperature on Selectivity

Dissociative chemisorption of ethanol on partially dehydroxylated silica is investigated by (i) exposing silica to gas-phase ethanol at various temperatures (ranging between 373 and 773?K) and (ii) analyzing the material using temperature-programmed desorption and in situ infrared spectroscopy. This chemisorption leads to formation of isolated surface ethoxide species via dehydration of ethanol at reaction temperatures above 573?K, and, at lower temperatures, it favors the synthesis of silanol?Cethoxide functionality via a pathway involving opening of siloxane Si?CO?CSi bridges. The activation barrier for ethene desorption from the isolated surface ethoxide species is considerably higher relative to that for ethanol desorption from the hydrogen-bound silanol?Cethoxide pairs. These single-turnover experiments allow predicting the product distribution of ethanol chemisorption on silica depending on the treatment conditions, e.g. temperature of interaction between ethanol and silica, and suggest why, in general, dehydration catalysis on silica requires high temperatures, in order to avoid non-productive chemisorption via opening of siloxane bridges.     

Evaluation of head response to ballistic helmet impacts using the finite element method

Injuries to the head caused by ballistic impacts are not well understood. Ballistic helmets provide good protection, but still, injuries to both the skull and brain occur. Today there is a lack of relevant test procedure to evaluate the efficiency of a ballistic helmet. The purpose of this project was (1) to study how different helmet shell stiffness affects the load levels in the human head during an impact, and (2) to study how different impact angles affects the load levels in the human head. A detailed finite element (FE) model of the human head, in combination with an FE model of a ballistic helmet (the US Personal Armour System Ground Troops’ (PASGT) geometry) was used. The head model has previously been validated against several impact tests on cadavers. The helmet model was validated against data from shooting tests. Focus was aimed on getting a realistic response of the coupling between the helmet and the head and not on modeling the helmet in detail. The studied data from the FE simulations were stress in the cranial bone, strain in the brain tissue, pressure in the brain, change in rotational velocity and translational and rotational acceleration. A parametric study was performed to see the influence of a variation in helmet shell stiffness on the outputs from the model. The effect of different impact angles was also studied. Dynamic helmet shell deflections larger than the initial distance between the shell and the skull should be avoided in order to protect the head from the most injurious threat levels. It is more likely that a fracture of the skull bone occurs if the inside of the helmet shell strikes the skull. Oblique ballistic impacts may in some cases cause higher strains in the brain tissue than pure radial ones.