Measurement of Suspended Sediment Transport Processes off the Holderness Coast - Southern North Sea, England

A field campaign was set up as part of the LOIS-RACS coastal program (1994-1996), to identify the near-bed physical processes responsible for suspended sediment movement in shallow water (10-20m depth) off the Holdemess coast, NE England. A new benthic tripod system Boundary Layer Intelligent Sensor System (BLISS) has been developed and deployed along a transect at three sites, normal to the coastline at Tunstall. Measurements of current velocity, suspended sediment concentration (SSC), pressure and CTD were recorded at 5 Hz for 17 minutes every hour, on the same data acquisition system. Results are presented for the summer, July 1995 and winter, February, 1996 deployments over two weeks. Results show that variation in the SSC signal is due to the advection of spatial gradients of SSC by the tidal flows and to the resuspension of sediment from the seabed. Alongshore advection is identified through a strong negative correlation between SSC and salinity, associated with the movement of low salinity, high turbidity water associated with the Humber plume to the south. Resuspension occurs predominantly during storms, when the influence of waves increases the friction velocity at the seabed (determined from measured turbulence spectra) above a threshold value. The threshold friction velocity in February 1996 was found to be approximately 0.023ms'', consistent with a partially consolidated fine sediment seabed. In July 1995, a much lower threshold velocity of 0.008 ms ' was measured and suggests that an unconsolidated layer of fine sediment can be deposited between the mild summer storms. After a winter storm, the decay time of the elevated SSC is consistent with a sediment settling velocity in the range (1.8-2.8) x 10"* ms"', a value which is associated with fine silt or flocculated clay particles. Sediment transport during the summer storms in July 1995 was onshore and is due to skewed shoaling waves suspending sediment during the shore-ward phase of the wave, as the wave crest passes. Offshore sediment transport dominated the February 1996 storms, and was due to a steady nearbed offshore flow explained by Stokes theory whereby a net flow in the direction of the wave advance near the surface will be balanced by a net flow in the opposite direction at depth. Sediment flux transport from waves along accounted for -10% of the total flux transported offshore. The storms are in fact, effective stirring mechanisms which increase the amount of sediment available for transport rather than actual transporters of suspended sediment

Phage display-derived inhibitor of the essential cell wall biosynthesis enzyme MurF

Background To develop antibacterial agents having novel modes of action against bacterial cell wall biosynthesis, we targeted the essential MurF enzyme of the antibiotic resistant pathogen Pseudomonas aeruginosa. MurF catalyzes the formation of a peptide bond between D-Alanyl-D-Alanine (D-Ala-D-Ala) and the cell wall precursor uridine 5'-diphosphoryl N-acetylmuramoyl-L-alanyl-D-glutamyl-meso-diaminopimelic acid (UDP-MurNAc-Ala-Glu-meso-A2pm) with the concomitant hydrolysis of ATP to ADP and inorganic phosphate, yielding UDP-N-acetylmuramyl-pentapeptide. As MurF acts on a dipeptide, we exploited a phage display approach to identify peptide ligands having high binding affinities for the enzyme. Results Screening of a phage display 12-mer library using purified P. aeruginosa MurF yielded to the identification of the MurFp1 peptide. The MurF substrate UDP-MurNAc-Ala-Glumeso-A2pm was synthesized and used to develop a sensitive spectrophotometric assay to quantify MurF kinetics and inhibition. MurFp1 acted as a weak, time-dependent inhibitor of MurF activity but was a potent inhibitor when MurF was pre-incubated with UDP-MurNAc-Ala-Glu-meso-A2pm or ATP. In contrast, adding the substrate D-Ala-D-Ala during the pre-incubation nullified the inhibition. The IC50 value of MurFp1 was evaluated at 250 μM, and the Ki was established at 420 μM with respect to the mixed type of inhibition against D-Ala-D-Ala. Conclusion MurFp1 exerts its inhibitory action by interfering with the utilization of D-Ala-D-Ala by the MurF amide ligase enzyme. We propose that MurFp1 exploits UDP-MurNAc-Ala-Glu-meso-A2pm-induced structural changes for better interaction with the enzyme. We present the first peptide inhibitor of MurF, an enzyme that should be exploited as a target for antimicrobial drug development

Vaccenic and Elaidic Acid Modify Plasma and Splenocyte Membrane Phospholipids and Mitogen-Stimulated Cytokine Production in Obese Insulin Resistant JCR: LA-cp Rats

This study assessed the long-term effects of dietary vaccenic acid (VA) and elaidic acid (EA) on plasma and splenocyte phospholipid (PL) composition and related changes in inflammation and splenocyte phenotypes and cytokine responses in obese/insulin resistant JCR:LA-cp rats. Relative to lean control (Ctl), obese Ctl rats had higher serum haptoglobin and impaired T-cell-stimulated cytokine responses. VA and EA diets improved T-cell-stimulated cytokine production; but, only VA normalized serum haptoglobin. However, EA- and VA-fed rats had enhanced LPS-stimulated cytokine responses. The changes elicited by VA were likely due changes in essential fatty acid composition in PL; whereas EA-induced changes may due to direct incorporation into membrane PL

A New Method for Simulation of Lunar Microwave Brightness Temperatures and Evaluation of Chang'E-2 MRM Data Using Thermal Constraints From Diviner

We used the bolometric brightness temperatures (T-Bol) derived from the Lunar Reconnaissance Orbiters Diviner Lunar Radiometer (Diviner) as an upper boundary condition in our thermal model. We then calculated temperature profiles at any local time based on our improved thermal model at low to middle latitudes (70 degrees N/S). Based on the temperature profiles, we modeled the midnight brightness temperature at 19.35 (T-B19) and 37GHz (T-B37). Comparing to the Chang'E-1 and Chang'E-2 (CE-1/2) observations, we found that CE-1 showed a better data quality than that of CE-2, especially for the T-B37 data. Assuming that the issue with the CE-2 data is caused by heat contamination of the cold-reference antennas, we performed an empirical normalization of the CE-2 microwave radiometer data near midnight following the approach of Hu et al. (2017). The results show that T-B difference (modeled values minus modified T-B) for 19.35GHz is less than 3.40K for approximate to 80% of the pixels. At 37GHz, approximate to 67% of the pixels have T-B difference less than 2.88K. Additionally, we identified some areas of low microwave temperature in our modified T-B maps. These low-T-B features can be characterized by two types: (1) low T-B spots at fresh craters with high rock abundance and bright rays and (2) high-Ti lunar mare surfaces with a low content of rock fragments. Investigating these low-T-B regions with the modified T-B data can reveal more information about subsurface thermal regime and properties and help us better understand the evolution of regolith on the Moon. Plain Language Summary We proposed a new method to simulate the microwave brightness temperature of the Moon using surface thermal constraints from Lunar Reconnaissance Orbiter Diviner data. We evaluated the Chang'E-1/2 microwave radiometer data and adjusted the midnight observations to account for its calibration uncertainties. Our results provide better constraints on the thermal regime in the subsurface. Of particular interest is microwave cold regions, the presence of which can be related to thermophysical and compositional properties of the regolith in these locations. The modified Chang'E-2 microwave data can also be applied to study the thermal evolution of the Moon

Randomized trial of cohesive short-stretch versus four-layer bandaging in the management of venous ulceration

A multicenter prospective randomized clinical trial was undertaken to compare a generic four-layer bandage system with a cohesive short-stretch system (Actico, Activa Healthcare) in the management of venous leg ulceration. Both systems are designed to produce sufficient pressure to counteract venous hypertension. Patients in leg ulcer services with leg ulceration were screened for inclusion in this trial. Patients with arterial disease (ankle brachial pressure index < 0.8) and causes of ulceration other than venous disease were excluded. For patients with bilateral ulceration, the limb with the larger area of ulceration was studied. Patients were randomized to receive either type of compression bandage and simultaneously randomized to one of two foam dressings that were changed weekly unless more frequent changes were clinically required. In all, 156 patients met entry criteria and were randomized from the 12 clinical centers with median (range) ulcer size of 4.33 (0.33–123.10) cm2. Analysis revealed that after 24 weeks a total of 111 (71%) of patients had complete ulcer closure, 32 (21%) had withdrawn from the trial, 12 (8%) remained with open ulceration, and one patient had died. Of the 74 patients randomized to the four-layer bandage, 51(69%) had ulcer closure on treatment compared with 60/82 (73%) on the cohesive short-stretch system. Intention-to-treat analysis produced a hazard ratio for healing of 1.08 (95 percent CI 0.63–1.85, p= 0.79). Withdrawal rates were similar between groups (15, 20% four-layer bandage; 17, 21% cohesive short-stretch system). Ulcer closure rates for patients treated with the cohesive short-stretch system were similar to those for patients managed by the four-layer bandage system in this trial

Mercury’s Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroidal Space Weathering Studies

Mercury's regolith, derived from the crustal bedrock, has been altered by a set of space weathering processes. Before we can interpret crustal composition, it is necessary to understand the nature of these surface alterations. The processes that space weather the surface are the same as those that form Mercury's exosphere (micrometeoroid flux and solar wind interactions) and are moderated by the local space environment and the presence of a global magnetic field. To comprehend how space weathering acts on Mercury's regolith, an understanding is needed of how contributing processes act as an interactive system. As no direct information (e.g., from returned samples) is available about how the system of space weathering affects Mercury's regolith, we use as a basis for comparison the current understanding of these same processes on lunar and asteroidal regoliths as well as laboratory simulations. These comparisons suggest that Mercury's regolith is overturned more frequently (though the characteristic surface time for a grain is unknown even relative to the lunar case), more than an order of magnitude more melt and vapor per unit time and unit area is produced by impact processes than on the Moon (creating a higher glass content via grain coatings and agglutinates), the degree of surface irradiation is comparable to or greater than that on the Moon, and photon irradiation is up to an order of magnitude greater (creating amorphous grain rims, chemically reducing the upper layers of grains to produce nanometer scale particles of metallic iron, and depleting surface grains in volatile elements and alkali metals). The processes that chemically reduce the surface and produce nanometer-scale particles on Mercury are suggested to be more effective than similar processes on the Moon. Estimated abundances of nanometer-scale particles can account for Mercury's dark surface relative to that of the Moon without requiring macroscopic grains of opaque minerals. The presence of nanometer-scale particles may also account for Mercury's relatively featureless visible-near-infrared reflectance spectra. Characteristics of material returned from asteroid 25143 Itokawa demonstrate that this nanometer-scale material need not be pure iron, raising the possibility that the nanometer-scale material on Mercury may have a composition different from iron metal [such as (Fe,Mg)S]. The expected depletion of volatiles and particularly alkali metals from solar-wind interaction processes are inconsistent with the detection of sodium, potassium, and sulfur within the regolith. One plausible explanation invokes a larger fine fraction (grain size <45 μm) and more radiation-damaged grains than in the lunar surface material to create a regolith that is a more efficient reservoir for these volatiles. By this view the volatile elements detected are present not only within the grain structures, but also as adsorbates within the regolith and deposits on the surfaces of the regolith grains. The comparisons with findings from the Moon and asteroids provide a basis for predicting how compositional modifications induced by space weathering have affected Mercury's surface composition