Behavioral thermoregulation in the American lobster Homarus americanus

It is generally accepted that water temperature has a strong influence on the behavior of the American lobster Homarus americanus. However, there is surprisingly little behavioral evidence to support this view. To haracterize the behavioral responses of lobsters to thermal gradients, three different experiments were conducted. In the first, 40 lobsters acclimated to summer water temperatures (summer-acclimated, 15.5±0.2 °C, mean ±S.E.M.) were placed individually in an experimental shelter, and the temperature in the shelter was gradually raised until the lobster moved out. Lobsters avoided water warmer than 23.5±0.4 °C, which was an increase of 8.0±0.4 °C from ambient summer temperatures. When this experiment was repeated with lobsters acclimated to winter temperatures (winter-acclimated, 4.3±0.1 °C), the lobsters (N=30) did not find temperature increases of the same magnitude (∆T=8.0±0.4 °C) aversive. The second experiment was designed to allow individual summer-acclimated lobsters (N=22) to select one of five shelters, ranging in temperature from 8.5 to 25.5 °C. After 24 h, 68 % of the lobsters occupied the 12.5 °C shelter, which was slightly above the ambient temperature (approximately 11 °C). In a similar experiment, winter-acclimated lobsters (N=30) were given a choice between two shelters, one at ambient temperature (4.6±0.2 °C) and one at a higher temperature (9.7±0.3 °C). Winter-acclimated lobsters showed a strong preference (90 %) for the heated shelter. In the final experiment, summer-acclimated lobsters (N=9) were allowed to move freely in a tank having a thermal gradient of approximately 10 °C from one end to the other. Lobsters preferred a thermal niche of 16.5±0.4 °C and avoided water that was warmer than 19 °C or colder than 13 °C. When standardized for acclimation temperature, lobsters preferred water 1.2±0.4 °C above their previous ambient temperature. Collectively, the results of these studies indicate that lobsters are capable of sensing water temperature and use this information to thermoregulate behaviorally. The implications of these findings for lobster behavior and distribution in their natural habitat are discussed

A Scoping Review of the Biological, Socioeconomic, and Environmental Determinants of Overweight and Obesity among Middle Eastern and Northern African Nationalities

Globally, and particularly in the Middle East and North Africa (MENA) region, obesity and overweight have become serious public health concerns. The objective of this scoping review is to identify and summarize the available data on the determinants of overweight and obesity among MENA nationalities. An extensive search was conducted of electronic databases, including Google Scholar, PUBMED, and PROQUEST, for articles published from 2007 until 2022.   Ten articles of the 333 that were found in the original search after filtering met the requirements for inclusion. Data extraction and quality assessment were applied to each of the selected studies. A thorough synthesis of the factors influencing overweight and obesity in MENA nationalities is provided by this scoping review. The results show the intricate interplay of anthropometric, behavioral, sociodemographic, and environmental factors that cause overweight and obesity in this population. Keywords: Overweight; Obesity; Body Mass Index; Oman

Gears Based on Carbon Nanotubes

Gears based on carbon nanotubes (see figure) have been proposed as components of an emerging generation of molecular- scale machines and sensors. In comparison with previously proposed nanogears based on diamondoid and fullerene molecules, the nanotube-based gears would have simpler structures and are more likely to be realizable by practical fabrication processes. The impetus for the practical development of carbon-nanotube- based gears arises, in part, from rapid recent progress in the fabrication of carbon nanotubes with prescribed diameters, lengths, chiralities, and numbers of concentric shells. The shafts of the proposed gears would be made from multiwalled carbon nanotubes. The gear teeth would be rigid molecules (typically, benzyne molecules), bonded to the nanotube shafts at atomically precise positions. For fabrication, it may be possible to position the molecular teeth by use of scanning tunneling microscopy (STM) or other related techniques. The capability to position individual organic molecules at room temperature by use of an STM tip has already been demonstrated. Routes to the chemical synthesis of carbon-nanotube-based gears are also under investigation. Chemical and physical aspects of the synthesis of molecular scale gears based on carbon nanotubes and related molecules, and dynamical properties of nanotube- based gears, have been investigated by computational simulations using established methods of quantum chemistry and molecular dynamics. Several particularly interesting and useful conclusions have been drawn from the dynamical simulations performed thus far: The forces acting on the gears would be more sensitive to local molecular motions than to gross mechanical motions of the overall gears. Although no breakage of teeth or of chemical bonds is expected at temperatures up to at least 3,000 K, the gears would not work well at temperatures above a critical range from about 600 to about 1,000 K. Gear temperature could probably be controlled by use of coolant gases. For a given application, the gears would work well at temperatures below the critical range, provided that the rotational energy was less than the energy required to tilt the teeth through an angle of 20 . The predominant mechanism of gear failure would be slippage caused by tilting of teeth. Gears would resume functioning if the slipping gears were decelerated sufficiently

Accelerating Tropicalization and the Transformation of Temperate Seagrass Meadows

Climate-driven changes are altering production and functioning of biotic assemblages in terrestrial and aquatic environments. In temperate coastal waters, rising sea temperatures, warm water anomalies and poleward shifts in the distribution of tropical herbivores have had a detrimental effect on algal forests. We develop generalized scenarios of this form of tropicalization and its potential effects on the structure and functioning of globally significant and threatened seagrass ecosystems, through poleward shifts in tropical seagrasses and herbivores. Initially, we expect tropical herbivorous fishes to establish in temperate seagrass meadows, followed later by megafauna. Tropical seagrasses are likely to establish later, delayed by more limited dispersal abilities. Ultimately, food webs are likely to shift from primarily seagrass-detritus to more direct-consumption-based systems, thereby affecting a range of important ecosystem services that seagrasses provide, including their nursery habitat role for fishery species, carbon sequestration, and the provision of organic matter to other ecosystems in temperate regions

Annual and Seasonal Surface Circulation Over the Mid-Atlantic Bight Continental Shelf Derived From a Decade of High Frequency Radar Observations

A decade (2007–2016) of hourly 6-km-resolution maps of the surface currents across the Mid-Atlantic Bight (MAB) generated by a regional scale High Frequency Radar network are used to reveal new insights into the spatial patterns of the annual and seasonal mean surface flows. Across the 10-year time series, temporal means and interannual and intra-annual variability are used to quantify the variability of spatial surface current patterns. The 10-year annual mean surface flows are weaker and mostly cross-shelf near the coast, increasing in speed and rotating to more alongshore directions near the shelfbreak, and increasing in speed and rotating to flow off-shelf in the southern MAB. The annual mean surface current pattern is relatively stable year to year compared to the hourly variations within a year. The 10-year seasonal means exhibit similar current patterns, with winter and summer more cross-shore while spring and fall transitions are more alongshore. Fall and winter mean speeds are larger and correspond to when mean winds are stronger and cross-shore. Summer mean currents are weakest and correspond to a time when the mean wind opposes the alongshore flow. Again, intra-annual variability is much greater than interannual, with the fall season exhibiting the most interseasonal variability in the surface current patterns. The extreme fall seasons of 2009 and 2011 are related to extremes in the wind and river discharge events caused by different persistent synoptic meteorological conditions, resulting in more or less rapid fall transitions from stratified summer to well-mixed winter conditions

Mathematical Habits of Mind for Teaching: Using Language in Algebra Classrooms

The notion of mathematical knowledge for teaching has been studied by many researchers, especially at the elementary grades. Our understandings of this notion parallel much of what we have read in the literature, but are based on our particular experiences over the past 20 years, as mathematicians engaged in doing mathematics with secondary teachers. As part of the work of Focus on Mathematics, Phase II MSP, we are developing, in collaboration with others in the field, a research program with the ultimate goal of understanding the connections between secondary teachers’ mathematical knowledge for teaching and secondary students’ mathematical understanding and achievement. We are in the early stages of a focused research study investigating the research question: What are the mathematical habits of mind that high school teachers use in their professional lives and how can we measure them? The main focus of this paper is the discussion of the habit of using mathematical language, and particularly how this habit plays out in a classroom setting

Effect of polishing procedures and hydrothermal aging on wear characteristics and phase transformation of zirconium dioxide

Statement of problem. Yttria-stabilized zirconia used for the fabrication of crowns and fixed prostheses may require intraoral adjustments after placement and cementation. Grinding and polishing methods may result in changes in the surface characteristics of zirconia. Purpose. The purpose of this in vitro study was to assess the effect of polishing procedures on surface roughness, topographical and phase changes of zirconia, and wear of the opposing dentition. Material and methods. Presintered and precut yttria-stabilized zirconia specimens (10×10×1 mm) were divided into 4 groups (control, Intensiv, Shofu, 3M ESPE) depending on the polishing method used to prepare the specimens. All tests were carried out in triplicate. The specimens were polished depending on the polishing regimen, while the control was left untreated. The specimens were thermocycled for 3000 cycles, with a temperature range of 5C to 55C. The surface roughness, elemental, and phase changes caused by polishing before and after thermocycling were assessed with surface profilometry, energy-dispersive spectroscopy, and X-ray diffraction analysis. The wear on antagonist steatite balls was also measured after mastication simulation. Statistical analysis was performed using 1-way ANOVA and the Tukey post hoc test to perform multiple comparison tests (a=.05). Results. The polishing procedures increased surface roughness (Ra) of yttria-stabilized zirconia from 0.52 for the control specimen to 0.73 for Intensiv, 0.70 for Shofu, and 0.70 for 3M ESPE (P<.05), which was reduced by thermocycling to 0.44 (control), 0.58 (Intensiv), and 0.58 (Shofu) (P<.001), while roughness remained unchanged for 3M ESPE specimens (0.75; P=.452). The deposition of aluminum when using Shofu abrasives and nickel in Intensiv was demonstrated. Phase changes were observed on the zirconia surface with formation of the monoclinic phase in all polishing methods. Specimen aging enhanced the surface phase changes and also induced compressive stresses in zirconia polished with Intensiv. The different polishing protocols did not affect the wear to the antagonist (P>.05). Conclusions. Polishing zirconia increased surface roughness and led to surface phase changes, but wear to the antagonist was not affected.peer-reviewe

Un esquema conceptual para identificar localidades con poblaciones en riesgo de anemia y desnutrición crónica

Datos nacionales e incluso departamentales de anemia y desnutrición crónica se recolectan con periodicidad. Es raro encontrar datos a nivel municipal del estado nutricional de una población, información necesaria para focalizar intervenciones. Un esquema conceptual se desarrolló, aplicó y válido. Datos bioquímicos (prevalencia departamental de hemoglobina infantil < 11 g/dL), antropométricos (prevalencia departamental de talla/edad infantil < -2 Desviación Estándar) y socioeconómicos (a nivel municipal, índice de intensidad de pobreza ó población bajo la línea de pobreza extrema) se usaron para identificar localidades con riesgo de presentar anemia y desnutrición crónica, en 11 países latinoamericanos. En un sistema de información geográfica, se unificaron datos nutricionales y socioeconómicos a un mismo formato espacial, que representaba una localidad en un determinado departamento de un país. Se ubicaron aquellas localidades donde coincidían alta desnutrición (anemia o crónica) y pobreza. Para la desnutrición crónica, hubo una alta relación de localidades identificadas con el esquema, al compararlas con datos recolectados a nivel municipal (= 66%), mas no cuando se comparó con un método estadístico (0%). Este esquema articulado a un software de mapeo facilitó la identificación de localidades con poblaciones en riesgo a anemia y desnutrición crónica. Es importante validar el esquema con estudios de campo