Composite vertices that lead to soft form factors

The momentum-space cut-off parameter $\Lambda$ of hadronic vertex functions is studied in this paper. We use a composite model where we can measure the contributions of intermediate particle propagations to $\Lambda$. We show that in many cases a composite vertex function has a much smaller cut-off than its constituent vertices, particularly when light constituents such as pions are present in the intermediate state. This suggests that composite meson-baryon-baryon vertex functions are rather soft, i.e., they have \Lambda considerably less than 1 GeV. We discuss the origin of this softening of form factors as well as the implications of our findings on the modeling of nuclear reactions.Comment: REVTex, 19 pages, 5 figs(to be provided on request

Search for He-eta bound states with the WASA-at-COSY facility

The existence of eta-mesic nuclei in which the eta meson is bound in a nucleus by means of the strong interaction was postulated already in 1986, albeit not yet confirmed it by experiment. The discovery of this new kind of an exotic nuclear matter would be very important as it might allow for a better understanding of the eta meson structure and its interaction with nucleons. The search for eta-mesic helium 4He-eta is carried out with high statistics and high acceptance with the WASA detector, installed at the cooler synchrotron COSY of the Research Center Juelich. The search is conducted via the measurement of the excitation function for selected decay channels of the 4He-eta system. In the experiment, performed in November 2010, two reactions dd->(4He-eta)bs ->3He p pi- and dd->(4He-eta)bs ->3He p pi0 were measured with a beam momentum ramped from 2.127GeV/c to 2.422GeV/c. The report includes the description of the experimental method and status of the measurement.Comment: Presented at the Erice School on Nuclear Physics 2011. 5 pages, 3 figure

Trace element studies on Karachi populations Part V: Blood lead levels in normal healthy adults and grammar school children

Blood lead levels of healthy Karachi population were estimated. Mean levels for males, females, soldiers and school children were 34.4, 31.8, 29.9 and 38.2 micrograms/dl respectively. About 93% cases of either sex had elevated lead levels, of whom 30% males and 10% females had levels above the safety limits (40 micrograms/dl). Soldiers living in relatively pollution free area though had levels lower than the rest of the population but 91% had levels over 25 micrograms/dl and only two had acceptable levels. Ninety-two percent children showed levels above 25 micrograms/dl with a large number having levels over 40 micrograms/dl. A very small percentage had normal levels. Pollution by traffic exhaust was assumed to be the principal cause for these high levels

Real-Time Noninvasive Estimation of Intrapleural Pressure in Mechanically Ventilated Patients: a Feasibility Study

A method for real-time noninvasive estimation of intrapleural pressure in mechanically ventilated patients is proposed. The method employs a simple first-order lung mechanics model that is fitted in real-time to flow and pressure signals acquired non-invasively at the opening of the patient airways, in order to estimate lung resistance (RL), lung compliance (CL) and intrapleural pressure (Ppl) continuously in time. Estimation is achieved by minimizing the sum of squared residuals between measured and model predicted airway pressure using a modified Recursive Least Squares (RLS) approach. Particularly, two different RLS algorithms, namely the conventional RLS with Exponential Forgetting (EF-RLS) and the RLS with Vector-type Forgetting Factor (VFF-RLS), are considered in this study and their performances are first evaluated using simulated data. Simulations suggest that the conventional EFRLS algorithm is not suitable for our purposes, whereas the VFF-RLS method provides satisfactory results. The potential of the VFF-RLS based method is then proved on experimental data collected from a mechanically ventilated pig. Results show that the method provides continuous estimated lung resistance and compliance in normal physiological ranges and pleural pressure in good agreement with invasive esophageal pressure measurements

Tibial Strains are Sensitive to Speed, but not Grade, Perturbations During Running

Tibial stress fractures are thought to result from a fatigue-failure process where bone failure is highly dependent on peak strain magnitude. Little is known regarding the mechanical loading environment of the tibia during graded running despite the prevalence of this terrain. To probe the sensitivity of the mechanical loading environment of the tibia to running grade, tibial strains were quantified using a combined musculoskeletal-finite element modeling routine during graded and level running. Seventeen participants ran on a treadmill at $\pm$10{\deg}, $\pm$5{\deg}, and 0{\deg} while force and motion data were captured. At each grade, participants ran at 3.33 m/s and a grade-adjusted speed, that was 2.20 m/s and 4.17 m/s for uphill and downhill conditions, respectively. Muscle and joint contact forces were estimated using inverse-dynamics-based static optimization. These forces were applied to a participant-informed finite element model of the tibia. 50th percentile pressure-modified von Mises strain was lower ($\leq$-130 $\mu\varepsilon$) during downhill running compared to level and uphill running at 3.33 m/s. However, neither 95th percentile strain (peak strain) nor the volume of bone experiencing strains $\geq$4000 $\mu\varepsilon$ (strained volume) were different between grades (F(4)$\leq$3.28, p$\geq$0.01). In contrast, peak strain and strained volume were highly sensitive to running speed (F(1)$\geq$10.61, p$\leq$0.001), where a 1 m/s increase in speed resulting in a 9 % and 155 % increase in peak strain and strained volume, respectively. Overall, these findings suggest that faster running speeds, but not changes in running grade, may increase the risk of developing a tibial stress fracture

Sialic acid transport and catabolism are cooperatively regulated by SiaR and CRP in nontypeable Haemophilus influenzae

BACKGROUND: The transport and catabolism of sialic acid, a critical virulence factor for nontypeable Haemophilus influenzae, is regulated by two transcription factors, SiaR and CRP. RESULTS: Using a mutagenesis approach, glucosamine-6-phosphate (GlcN-6P) was identified as a co-activator for SiaR. Evidence for the cooperative regulation of both the sialic acid catabolic and transport operons suggested that cooperativity between SiaR and CRP is required for regulation. cAMP was unable to influence the expression of the catabolic operon in the absence of SiaR but was able to induce catabolic operon expression when both SiaR and GlcN-6P were present. Alteration of helical phasing supported this observation by uncoupling SiaR and CRP regulation. The insertion of one half-turn of DNA between the SiaR and CRP operators resulted in the loss of SiaR-mediated repression of the transport operon while eliminating cAMP-dependent induction of the catabolic operon when GlcN-6P was present. SiaR and CRP were found to bind to their respective operators simultaneously and GlcN-6P altered the interaction of SiaR with its operator. CONCLUSIONS: These results suggest multiple novel features for the regulation of these two adjacent operons. SiaR functions as both a repressor and an activator and SiaR and CRP interact to regulate both operons from a single set of operators