Droplet motion driven by surface freezing or melting: A mesoscopic hydrodynamic approach

A fluid droplet may exhibit self-propelled motion by modifying the wetting properties of the substrate. We propose a novel model for droplet propagation upon a terraced landscape of ordered layers formed as a result of surface freezing driven by the contact angle dependence on the terrace thickness. Simultaneous melting or freezing of the terrace edge results in a joint droplet-terrace motion. The model is tested numerically and compared to experimental observations on long-chain alkane system in the vicinity of the surface melting point.Comment: 4 pages, 3 figure

A Novel Strategy for Selective O-Methylation of Glycerol in Subcritical Methanol

A new regioselective approach has been elaborated for the selective conversion of bio-based glycerol into the monomethyl derivative using sub/supercritical methanol. The reaction was realized in a batch process using three reactive components, namely, glycerol, methanol, and potassium carbonate to selectively produce the 3-methoxypropan-1,2-diol in mild yields; the mechanism of the O-methylation has been delineated using labeled methanol and GC-MS experiments

Designing a shipboard line transect survey to estimate cetacean abundance off the Azores archipelago

Management schemes dedicated to the conservation of wildlife populations rely on the effective monitoring of population size, and this may require the accurate and precise estimation of this parameter. Line transect distance sampling can be an effective approach for estimating abundance. Little information is available regarding cetacean abundance in the Azores. This paper had two aims: 1) to design a line transect shipboard survey to estimate the absolute abundance of the most common cetaceans off the Azores; and 2) to provide a set of potential survey effort scenarios to policy makers and environmental managers. Three survey scenarios are assessed, and one detailed survey design is presented. A total of 8,800 km of survey effort is recommended; at this level the expected coefficient of variation of estimates is less than 0.3 for most species. However, if logistic constraints prevent this, at least 5,000 km of survey effort should be used to achieve minimum sample size requirements; this is estimated to take 36 days of effort. It is also recommended to conduct a pilot survey. This would provide more detailed information that could be used to improve the survey design of what would be the first survey of this magnitude ever to be implemented in the Azores

Bostonia: v. 64, no. 1

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Interaction of Vortices in Complex Vector Field and Stability of a ``Vortex Molecule''

We consider interaction of vortices in the vector complex Ginzburg--Landau equation (CVGLE). In the limit of small field coupling, it is found analytically that the interaction between well-separated defects in two different fields is long-range, in contrast to interaction between defects in the same field which falls off exponentially. In a certain region of parameters of CVGLE, we find stable rotating bound states of two defects -- a ``vortex molecule".Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let

Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California

The article of record as published may be located at https://doi.org/10.1016/j.dsr2.2014.10.008Funded by Naval Postgraduate SchoolTrends in cetacean density and distribution off southern California were assessed through visual line- transect surveys during thirty-seven California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from July 2004–November 2013. From sightings of the six most commonly encountered cetacean species, seasonal, annual and overall density estimates were calculated. Blue whales (Balaenoptera musculus), fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) were the most frequently sighted baleen whales with overall densities of 0.91/1000 km2 (CV 1⁄4 0.27), 2.73/ 1000 km2 (CV 1⁄4 0.19), and 1.17/1000 km2 (CV 1⁄4 0.21) respectively. Species specific density estimates, stratified by cruise, were analyzed using a generalized additive model to estimate long-term trends and correct for seasonal imbalances. Variances were estimated using a non-parametric bootstrap with one day of effort as the sampling unit. Blue whales were primarily observed during summer and fall while fin and humpback whales were observed year-round with peaks in density during summer and spring respectively. Short-beaked common dolphins (Delphinus delphis), Pacific white-sided dolphins (Lagen- orhynchus obliquidens) and Dall’s porpoise (Phocoenoidesdalli) were the most frequently encountered small cetaceans with overall densities of 705.83/1000 km2 (CV1⁄40.22), 51.98/1000 km2 (CV1⁄40.27), and 21.37/1000 km2 (CV 1⁄4 0.19) respectively. Seasonally, short-beaked common dolphins were most abun- dant in winter whereas Pacific white-sided dolphins and Dall’s porpoise were most abundant during spring. There were no significant long-term changes in blue whale, fin whale, humpback whale, short- beaked common dolphin or Dall’s porpoise densities while Pacific white-sided dolphins exhibited a significant decrease in density across the ten-year study. The results from this study were fundamentally consistent with earlier studies, but provide greater temporal and seasonal resolution.Funding was provided by the Chief of Naval Operations Environmental Readiness Division, the United States Navy’s Pacific Fleet, the Naval Postgraduate School Grant #N00244-11-1-027, and the Naval Facilities Engineering Command Living Marine Resources Pro- gramFunding was provided by the Chief of Naval Operations Environmental Readiness Division, the United States Navy’s Pacific Fleet, the Naval Postgraduate School Grant #N00244-11-1-027, and the Naval Facilities Engineering Command Living Marine Resources Pro- gra

Quantifying the response of Blainville’s beaked whales to U.S. naval sonar exercises in Hawaii

Funding: US Navy Living Marine Resources Program (Grant Number(s): N39430-17-P-1983).Behavioral responses of beaked whales (family Ziphiidae) to naval use of mid-frequency active sonar (MFAS) have been quantified for some species and regions. We describe the effects of MFAS on the probability of detecting diving groups of Blainville's beaked whales on the U.S. Navy Pacific Missile Range Facility (PMRF) in Hawaii and compare our results to previously published results for the same species at the Atlantic Undersea Test and Evaluation Center (AUTEC) in the Bahamas. We use passive acoustic data collected at bottom-mounted hydrophones before and during six naval training exercises at PMRF along with modelled sonar received levels to describe the effect of training and MFAS on foraging groups of Blainville's beaked whales. We use a multistage generalized additive modeling approach to control for the underlying spatial distribution of vocalizations under baseline conditions. At an MFAS received level of 150 dB re 1 μPa rms the probability of detecting groups of Blainville's beaked whales decreases by 77%, 95% CI [67%, 84%] compared to periods when general training activity was ongoing and by 87%, 95% CI [81%, 91%] compared to baseline conditions. Our results indicate a more pronounced response to naval training and MFAS than has been previously reported.Publisher PDFPeer reviewe

Mixture models for distance sampling detection functions

Funding: EPSRC DTGWe present a new class of models for the detection function in distance sampling surveys of wildlife populations, based on finite mixtures of simple parametric key functions such as the half-normal. The models share many of the features of the widely-used “key function plus series adjustment” (K+A) formulation: they are flexible, produce plausible shapes with a small number of parameters, allow incorporation of covariates in addition to distance and can be fitted using maximum likelihood. One important advantage over the K+A approach is that the mixtures are automatically monotonic non-increasing and non-negative, so constrained optimization is not required to ensure distance sampling assumptions are honoured. We compare the mixture formulation to the K+A approach using simulations to evaluate its applicability in a wide set of challenging situations. We also re-analyze four previously problematic real-world case studies. We find mixtures outperform K+A methods in many cases, particularly spiked line transect data (i.e., where detectability drops rapidly at small distances) and larger sample sizes. We recommend that current standard model selection methods for distance sampling detection functions are extended to include mixture models in the candidate set.Publisher PDFPeer reviewe