Magnetic Response of Magnetospirillum Gryphiswaldense

In this study we modelled and measured the U-turn trajectories of individual magnetotactic bacteria under the application of rotating magnetic fields, ranging in ampitude from 1 to 12 mT. The model is based on the balance between rotational drag and magnetic torque. For accurate verification of this model, bacteria were observed inside 5 m tall microfluidic channels, so that they remained in focus during the entire trajectory. From the analysis of hundreds of trajectories and accurate measurements of bacteria and magnetosome chain dimensions, we confirmed that the model is correct within measurement error. The resulting average rate of rotation of Magnetospirillum Gryphiswaldense is 0.74 +- 0.03 rad/mTs.Comment: 17 pages, 12 figure

Square character degree graphs yield direct products

If $G$ is a solvable group, we take $\Delta (G)$ to be the character degree graph for $G$ with primes as vertices. We prove that if $\Delta (G)$ is a square, then $G$ must be a direct product

Application of SWASH to Compute Wave Overtopping in Ericeira Harbour for operational purposes

This work aimed at testing the capability of the numerical model SWASH to be implemented in the prototype of the overtopping and flooding forecast system HIDRALERTA for Ericeira harbour. In contrast to the neural network NN_OVERTOPPING2, which is currently implemented in HIDRALERTA, SWASH is able to estimate the flood extension and wave propagation along the domain, which makes it a possible improvement to NN_OVERTOPPING2. The one-dimensional version of the SWASH model was implemented to simulate overtopping at two different profiles (antifer and tetrapods) and calibrated for three storms in 2019 by comparing the simulated overtopping discharge to NN_OVERTOPPING2 results. For the calibration, the Manning coefficient was used to represent the friction of the armour layer. Then, for operational purposes, four expressions to calculate the Manning coefficient were developed based on: the relative crest freeboard, the wave steepness, the incident wave angle and the type of armour layer. The expressions showed small errors between the calculated and calibrated Manning coefficients and highlighted the importance of the incident wave angle to obtain an accurate calibration. Despite an underestimation of the overtopping discharge in some cases, the SWASH model was found to provide overall good results when applied with calculated Manning coefficients and suitable to be implemented in HIDRALERTA.info:eu-repo/semantics/publishedVersio

Thermalization in a quasi-1D ultracold bosonic gas

We study the collisional processes that can lead to thermalization in one-dimensional systems. For two body collisions excitations of transverse modes are the prerequisite for energy exchange and thermalzation. At very low temperatures excitations of transverse modes are exponentially suppressed, thermalization by two body collisions stops and the system should become integrable. In quantum mechanics virtual excitations of higher radial modes are possible. These virtually excited radial modes give rise to effective three-body velocity-changing collisions which lead to thermalization. We show that these three-body elastic interactions are suppressed by pairwise quantum correlations when approaching the strongly correlated regime. If the relative momentum $k$ is small compared to the two-body coupling constant $c$ the three-particle scattering state is suppressed by a factor of $(k/c)^{12}$, which is proportional to $\gamma ^{12}$, that is to the square of the three-body correlation function at zero distance in the limit of the Lieb-Liniger parameter $\gamma \gg 1$. This demonstrates that in one dimensional quantum systems it is not the freeze-out of two body collisions but the strong quantum correlations which ensures absence of thermalization on experimentally relevant time scales.Comment: revtex4, 3 figures. Final version of the text, accepted for publication (see journal ref.

Switching cell fate by the actin–auxin oscillator in Taxus: cellular aspects of plant cell fermentation

Plant cell fermentation, the production of valuable products in plant cell culture, has great potential as sustainable alternative to the exploitation of natural resources for compounds of pharmaceutical interest. However, the success of this approach has remained limited, because the cellular aspects of metabolic competence are mostly unknown. The production of the anti-cancer alkaloid Paclitaxel has been, so far, the most successful case for this approach. In the current work, we map cellular aspects of alkaloid synthesis in cells of Taxus chinensis using a combination of live-cell imaging, quantitative physiology, and metabolite analysis. We show evidence that metabolic potency correlates with a differentiation event giving rise to cells with large vacuoles with a tonoplast that is of a glossy appearance, agglomerations of lipophilic compounds, and multivesicular bodies that fuse with the plasma membrane. Cellular features of these glossy cells are bundled actin, more numerous peroxisomes, and vermiform mitochondria. The incidence of glossy cells can be increased by aluminium ions, and this increase is significantly reduced by the actin inhibitor Latrunculin B, and by diphenylene iodonium, a specific inhibitor of the NADPH oxidase Respiratory burst oxidase Homologue (RboH). It is also reduced by the artificial auxin Picloram. This cellular fingerprint matches the implications of a model, where the differentiation into the glossy cell type is regulated by the actin–auxin oscillator that in plant cells acts as dynamic switch between growth and defence

High-speed video observation and on-line measurements of oil aeration in an internal combustion engine

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 91-92).Along the oil's journey through the oil lube system, the oil lubricates, cools, removes impurities, supports load, and minimizes friction. At the end of the oil's journey it returns to the sump where it remains nearly motionless until it re-enters the oil pick-up and restarts its journey. This study is focused on the creation and destruction mechanisms of air in the oil. To study this, a motored Ford 3.OL V6 DOHC engine test apparatus was designed, fabricated and instrumented to operate at 8000rpm and at engine oil temperatures below 110ÌC. Visual observations and quantitative measurements of oil aeration were performed in the oil sump. The oil aeration process was visualized in the oil sump using high-speed video equipment, at engine speeds below 4000rpm. Oil droplets were observed to depart the crankshaft at approximately the tangential velocity, pass through drainage gaps in the windage tray, and strike the free surface of the oil. The rhythmic pulsation of oil droplets on the free surface caused the surface to slosh at the frequency of the crankshaft's rotation. Foam was observed to form above a threshold speed and a threshold temperature. The windage tray was observed to reduce the droplet number density. When the windage tray was removed, the increased droplet number density inhibited foam formation. An x-ray absorption measurement technique was used to measure oil aeration at multiple locations in the oil sump. An experimental methodology was developed and preliminary experiments were performed with and without the windage tray at oil volumes below 5L, engine speeds below 6000rpm, and oil temperatures below 110ÌC.(cont.) Aeration measurements reveal a general increase in aeration as a function of engine speed at all locations in the oil sump. In the oil sump, more air is present at the oil surface than at the oil pick-up because air continuously leaves the oil at the air-oil interface. When the engine shuts down, all of the oil in the lube path drains back into the oil sump, and in a short period of time all of the air bubbles rise to the surface and escape the oil. It is the balance between air entering the oil (creation mechanisms) and air leaving the oil (destruction mechanisms) that is the focus of this study.by Devon L. Manz.S.M

Prevalence and severity of dental caries among American Indian and Alaska Native preschool children

Objectives: To describe the Indian Health Service (IHS) oral health surveillance system and the oral health status of American Indian and Alaska Native (AI/AN) children aged 1‐5 years. Methods: A stratified probability sample of IHS/tribal sites was selected. Children were screened by trained examiners at community‐based locations including medical clinics, Head Start, preschools, kindergarten, and Women, Infants, and Children (WIC). Data collection was limited to the primary dentition and included number of teeth present plus number of teeth with cavitated lesions, restorations, and extracted because of decay. Number of molars with sealants and urgency of need for dental care data were also obtained. Statistical analyses were performed with SAS (SAS Institute Inc., Cary, NC, USA). Sample weights were used to produce population estimates based on selection probabilities. Results: A total of 8,461 AI/AN children 12‐71 months of age were screened at 63 IHS/tribal sites, approximately 7 percent of the estimated IHS user population of the same age. Overall, 54 percent of the children had decay experience, 39 percent had untreated decay, 7 percent had primary molar sealants, 36 percent needed early or urgent dental care, and 6 percent needed urgent dental care. The mean of decayed, missing, or filled teeth was 3.5 (95 percent confidence interval, 3.1‐3.9). The prevalence of decay experience increased with age; 21 percent of 1‐year‐olds and 75 percent of 5‐year‐olds had a history of caries. When stratified by IHS area, there were substantial differences in the oral health of preschool children. Conclusions: The results confirm that in the United States, AI/AN children served by IHS/tribal programs are one of the racial/ethnic groups at highest risk of caries.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93514/1/j.1752-7325.2012.00331.x.pd

Shotgun ion mobility mass spectrometry sequencing of heparan sulfate saccharides

Despite evident regulatory roles of heparan sulfate (HS) saccharides in numerous biological processes, definitive information on the bioactive sequences of these polymers is lacking, with only a handful of natural structures sequenced to date. Here, we develop a “Shotgun” Ion Mobility Mass Spectrometry Sequencing (SIMMS2) method in which intact HS saccharides are dissociated in an ion mobility mass spectrometer and collision cross section values of fragments measured. Matching of data for intact and fragment ions against known values for 36 fully defined HS saccharide structures (from di- to decasaccharides) permits unambiguous sequence determination of validated standards and unknown natural saccharides, notably including variants with 3O-sulfate groups. SIMMS2 analysis of two fibroblast growth factor-inhibiting hexasaccharides identified from a HS oligosaccharide library screen demonstrates that the approach allows elucidation of structure-activity relationships. SIMMS2 thus overcomes the bottleneck for decoding the informational content of functional HS motifs which is crucial for their future biomedical exploitation

The I-mode confinement regime at ASDEX Upgrade: global propert ies and characterization of strongly intermittent density fluctuations

Properties of the I­mode confinement regime on the ASDEX Upgrade tokamak are summarized. A weak dependence of the power threshold for the L­I transition on the toroidal magnetic field strength is found. During improved confinement, the edge radial electric field well deepens. Stability calculations show that the I­mode pedestal is peeling­ballooning stable. Turbulence investigations reveal strongly intermittent density fluctuations linked to the weakly coherent mode in the confined plasma, which become stronger as the confinement quality increases. Across all investigated structure sizes ( ≈ ⊥ k 5 – 12 cm − 1 , with ⊥ k the perpendicular wavenumber of turbulent density fluctuations), the intermittent turbulence bursts are observed. Comparison with bolometry data shows that they move poloidally toward the X­point and finally end up in the divertor. This might be indicative that they play a role in inhibiting the density profile growth, such that no pedestal is formed in the edge density profile.European Union (EUROfusion 633053)European Union (EUROfusion AWP15­ENR­09/IPP­02

Implementation of the SWASH model into HIDRALERTA system

Early warning systems are an important tool for local authorities to detect emergency situations in advance and initiate the necessary safety measure. The To-SEAlert project has the aim of increasing the efficiency, robustness and reliability of the HIDRALERTA early warning system. This study shows a first intent to implement the SWASH model to simulate wave overtopping for the Ericeira prototype. SWASH was implemented for one breakwater profile used to simulate the overtopping discharge and evaluate the associated risk levels. It was compared to the current approach used in HIDRALERTA, which resorts to a neural network trained with a physical modelling database, NN_OVERTOPPING2. Finally, both approaches were compared with previously analyzed video images of the breakwater. The results showed that SWASH generally overestimates overtopping and is not in good agreement with the video images. NN_OVERTOPPING2 has a better agreement with the video images. A possible reason for the overestimation might be the wave direction, which cannot be included in one-dimensional simulations in SWASH