Lowest energy excited singlet states of isomers of alkyl substituted hexatrienes

Vibrationally resolved S0S1 excitation spectra for the alkyl substituted linear polyenes heptatriene, octatriene, and decatriene seeded into a supersonic He expansion have been measured by resonance enhanced multiphoton ionization spectroscopy. As is the case for the parent compound hexatriene, the lowest energy excited singlet state in all of these molecules is the 2 1Ag state. The measurement of S0S1 excitation spectra of three of the four double bond isomers of heptatriene gives a detailed picture of the dependence of the electronic structure of the 2 1Ag state on molecular conformation. The three isomers for which spectra are presented have the cis configuration at either the central or the alkyl substituted double bond, or both. For the case of the mono cis species with the cis configuration at the alkyl substituted double bond the spectra show the presence of two single bond conformers. Because of the increased number of distinguishable isomers and conformers for octatriene and decatriene we were unable to unambiguously separate the observed spectra of these molecules into contributions from single specific molecular conformations. However, the increased excitation intensity in the low frequency region relative to that in the C-C and C=C stretching region for octatriene and decatriene as compared to heptatriene suggests that vibrational relaxation is enhanced in the more complex molecules. In the case of unsubstituted hexatriene, previously reported spectra show that the 2 1Ag state has lower symmetry than does the ground state (most likely due to nonplanarity at the terminal carbon atoms). There is no evidence for an analogous distortion in the excitation spectra measured for the alkyl substituted hexatrienes. The Journal of Chemical Physics is copyrighted by The American Institute of Physics

Multiple Roles of Component Proteins in Bacterial Multicomponent Monooxygenases: Phenol Hydroxylase and Toluene/o-Xylene Monooxygenase from Pseudomonas sp. OX1.

Phenol hydroxylase (PH) and toluene/o-xylene monooxygenase (ToMO) from Pseudomonas sp. OX1 require three or four protein components to activate dioxygen for the oxidation of aromatic substrates at a carboxylate-bridged diiron center. In this study, we investigated the influence of the hydroxylases, regulatory proteins, and electron-transfer components of these systems on substrate (phenol; NADH) consumption and product (catechol; H(2)O(2)) generation. Single-turnover experiments revealed that only complete systems containing all three or four protein components are capable of oxidizing phenol, a major substrate for both enzymes. Under ideal conditions, the hydroxylated product yield was ∼50% of the diiron centers for both systems, suggesting that these enzymes operate by half-sites reactivity mechanisms. Single-turnover studies indicated that the PH and ToMO electron-transfer components exert regulatory effects on substrate oxidation processes taking place at the hydroxylase actives sites, most likely through allostery. Steady state NADH consumption assays showed that the regulatory proteins facilitate the electron-transfer step in the hydrocarbon oxidation cycle in the absence of phenol. Under these conditions, electron consumption is coupled to H(2)O(2) formation in a hydroxylase-dependent manner. Mechanistic implications of these results are discussed

Effect of Phosphorus and Strontium Additions on Formation Temperature and Nucleation Density of Primary Silicon in Al-19 Wt Pct Si Alloy and Their Effect on Eutectic Temperature

The influence of P and Sr additions on the formation temperature and nucleation density of primary silicon in Al-19 wt pct Si alloy has been determined, for small volumes of melt solidified at cooling rates _T of ~0.3 and 1 K/s. The proportion of ingot featuring primary silicon decreased progressively with increased Sr addition, which also markedly reduced the temperature for first formation of primary silicon and the number of primary silicon particles per unit volume �Nv: When combined with previously published results, the effects of amount of P addition and cooling rate on �Nv are in reasonable accord with �Nv� _T ¼ ðp=6fÞ1=2 109 [250 � 215 (wt pct P)0.17]�3, where �Nv is in mm�3, _T is in K/s, and f is volume fraction of primary silicon. Increased P addition reduces the eutectic temperature, while increased Sr appears to generate a minimum in eutectic temperature at about 100 ppmw Sr

High frequency variations of Helicobacter pylori isolates in individual hosts in a Chinese population

SummaryBackgroundColonization of individual hosts by multiple Helicobacter pylori genotypes may be one reason why this infection is persistent and difficult to eradicate.MethodsIn order to study the diversity of H. pylori in individuals, a modified randomly amplified polymorphic DNA (RAPD) method was applied using primary culture isolates instead of passaged cultures.ResultsThe results showed that variations in H. pylori were prevalent among individuals in the Chinese population, and the incidence of multiple colonization was 99.1% (115/116), significantly higher than in other reports. Moreover, the number of RAPD genotypes was found to be significantly associated with the process of disease development (p<0.05). Indeed, a trend for a higher number of RAPD genotypes within a single host (up to five genotypes) was observed as the disease developed or became more serious. After subculturing for three generations in our experiment, some genotypes present in the primary cultures were lost. The different genotypes in one patient may have originated from a single ancestral strain, as determined by analysis of six H. pylori housekeeping gene alleles, most of which were shown to be identical.ConclusionsThese results suggest that investigating isolates of the primary culture will better reflect the H. pylori diversity in individuals. Also, they indicate that continuous variation of one strain in the gastric microenvironment may be the main cause of H. pylori diversity in individuals in the Chinese population

Possible Role of Protein CPG15 in Hippocampal Mossy Fiber Sprouting Under Conditions of Pentylenetetrazole Kindling

We examined changes in expression of the candidate plasticity-related gene 15 (CPG15) in the dentate gyrus (DG) and hippocampal CA3 region in the pentylenetetrazole (PTZ) kindling model and investigated the role of this gene in the phenomenon of mossy fiber sprouting (MFS). Experimental rats were divided into the control and PTZ groups. The epileptic model was created by intraperitoneal PTZ injection, while control rats were injected with saline. At days 3, 7, 14, 28, and 42 after the first PTZ injection, Timm staining was scored in the CA3 hippocampal area, and a product of CPG15 (protein CPG15) was labeled in the DG stratum granulosum and in the CA3 area using immunohistochemistry. The Timm scores in the CA3 region increased gradually from day 3 and were significantly higher than those in the control within the subsequent period. The level of CPG15 protein in the DG and CA3 area decreased gradually until day 14 and returned to the normal level at day 28. The results obtained indicate, for the first time, that CPG15 may be involved in the process of MFS. Understanding the molecular mechanisms underlying this phenomenon may lead to successful therapeutic interventions that limit epileptogenesis.Ми досліджували зміни експресії продукту гена CPG15 у зубчастій звивині (ЗЗ) та зоні CA3 гіпокампа в моделі пентилентетразолового (ПТЗ-) кіндлінгу та можливу роль цього гена у феномені спрутингу моховитих волокон (СМВ). Піддослідні щури були поділені на групи контролю та ПТЗ-кіндлінгу. Модель епілепсії створювали за допомогою внутрішньоочеревинних ін’єкцій пентилентетразолу (ПТЗ); контрольним щурам ін’єкували фізіологічний розчин. На третю, сьому, 14-ту, 28-му та 42-гу добу після першої ін’єкції ПТЗ оцінювали забарвлення, за Тіммом, у зоні CA3. Локалізацію протеїну CPG15 у stratum granulosum ЗЗ та зоні CA3 гіпокампа визначали з використанням імуногістохімічної методики. Інтенсивність забарвлення, за Тіммом, у зоні CA3 поступово збільшувалася починаючи з третьої доби та була вірогідно вищою, ніж така в контролі, протягом усього наступного періоду. Рівень протеїну CPG15 у ЗЗ та полі CA3 поступово зменшувався до 14-ї доби та повертався до нормальних значень на 28-му добу. Отримані результати вперше вказують на те, що CPG15 може бути залученим у процес СМВ. Зрозуміння молекулярних механізмів, на яких базується цей феномен, може призвести до розробки успішних терапевтичних заходів, котрі обмежували б епілептогенез

Effects of R-parity Violation on the Charged Higgs Boson Decays

We calculate one-loop R-parity-violating couplings corrections to the processes $H^-\to \tau\bar{\nu_\tau}$ and $H^-\to b\bar{t}$. We find that the corrections to the $H^-\to \tau\bar{\nu_\tau}$ decay mode are generally about 0.1%, and can be negligible. But the corrections to the $H^-\to b\bar{t}$ decay mode can reach a few percent for the favored parameters.Comment: 17 pages,6 figures. One type error in the title correcte

Coupled dark matter-dark energy in light of near Universe observations

Cosmological analysis based on currently available observations are unable to rule out a sizeable coupling among the dark energy and dark matter fluids. We explore a variety of coupled dark matter-dark energy models, which satisfy cosmic microwave background constraints, in light of low redshift and near universe observations. We illustrate the phenomenology of different classes of dark coupling models, paying particular attention in distinguishing between effects that appear only on the expansion history and those that appear in the growth of structure. We find that while a broad class of dark coupling models are effectively models where general relativity (GR) is modified --and thus can be probed by a combination of tests for the expansion history and the growth of structure--, there is a class of dark coupling models where gravity is still GR, but the growth of perturbations is, in principle modified. While this effect is small in the specific models we have considered, one should bear in mind that an inconsistency between reconstructed expansion history and growth may not uniquely indicate deviations from GR. Our low redshift constraints arise from cosmic velocities, redshift space distortions and dark matter abundance in galaxy voids. We find that current data constrain the dimensionless coupling to be |xi|<0.2, but prospects from forthcoming data are for a significant improvement. Future, precise measurements of the Hubble constant, combined with high-precision constraints on the growth of structure, could provide the key to rule out dark coupling models which survive other tests. We shall exploit as well weak equivalence principle violation arguments, which have the potential to highly disfavour a broad family of coupled models.Comment: 34 pages, 6 figures; changes to match published versio

User Interaction in Semi-Automatic Segmentation of Organs at Risk: a Case Study in Radiotherapy

Accurate segmentation of organs at risk is an important step in radiotherapy planning. Manual segmentation being a tedious procedure and prone to inter- and intra-observer variability, there is a growing interest in automated segmentation methods. However, automatic methods frequently fail to provide satisfactory result, and post-processing corrections are often needed. Semi-automatic segmentation methods are designed to overcome these problems by combining physicians’ expertise and computers’ potential. This study evaluates two semi-automatic segmentation methods with different types of user interactions, named the “strokes” and the “contour”, to provide insights into the role and impact of human-computer interaction. Two physicians participated in the experiment. In total, 42 case studies were carried out on five different types of organs at risk. For each case study, both the human-computer interaction process and quality of the segmentation results were measured subjectively and objectively. Furthermore, different measures of the process and the results were correlated. A total of 36 quantifiable and ten non-quantifiable correlations were identified for each type of interaction. Among those pairs of measures, 20 of the contour method and 22 of the strokes method were strongly or moderately correlated, either directly or inversely. Based on those correlated measures, it is concluded that: (1) in the design of semi-automatic segmentation methods, user interactions need to be less cognitively challenging; (2) based on the observed workflows and preferences of physicians, there is a need for flexibility in the interface design; (3) the correlated measures provide insights that can be used in improving user interaction design

Dietary Intake of Total, Animal, and Vegetable Protein and Risk of Type 2 Diabetes in the European Prospective Investigation into Cancer and Nutrition (EPIC)-NL Study

OBJECTIVE - Dietary recommendations are focused mainly on relative dietary fat and carbohydrate content in relation to diabetes risk. Meanwhile, high-protein diets may contribute to disturbance of glucose metabolism, but evidence from prospective studies is scarce. We examined the association among dietary total, vegetable, and animal protein intake and diabetes incidence and whether consuming 5 energy % from protein at the expense of 5 energy % from either carbohydrates or fat was associated with diabetes risk. RESEARCH DESIGN AND METHODS - A prospective cohort study was conducted among 38,094 participants of the European Prospective Investigation into Cancer and Nutrition (EPIC)-NL study. Dietary protein intake was measured with a validated food frequency questionnaire. Incident diabetes was verified against medical records. RESULTS - During 10 years of follow-up, 918 incident cases of diabetes were documented. Diabetes risk increased with higher total protein (hazard ratio 2.15 [95% CI 1.77-2.60] highest vs. lowest quartile) and animal protein (2.18 [1.80 -2.63]) intake. Adjustment for confounders did not materially change these results. Further adjustment for adiposity measures attenuated the associations. Vegetable protein was not related to diabetes. Consuming 5 energy % from total or animal protein at the expense of 5 energy % from carbohydrates or fat increased diabetes risk. CONCLUSIONS - Diets high in animal protein are associated with an increased diabetes risk. Our findings also suggest a similar association for total protein itself instead of only animal sources. Consumption of energy from protein at the expense of energy from either carbohydrates or fat may similarly increase diabetes risk. This finding indicates that accounting for protein content in dietary recommendations for diabetes prevention may be useful