Irreversible processes and the accelerated-decelerated phases of the Universe

A model for the Universe is proposed where it is considered as a mixture of scalar and matter fields. The particle production is due to an irreversible transfer of energy from the gravitational field to the matter field and represented by a non-equilibrium pressure. This model can simulate three distinct periods of the Universe: (a) an accelerated epoch where the energy density of the scalar field prevails over the matter field, (b) a past decelerated period where the energy density of the matter field becomes more predominant than the scalar energy density, and (c) a present acceleration phase where the scalar energy density overcomes the energy density of the matter field.Comment: 6 pages, 2 figures, to be published in Brazilian Journal of Physic

An Examination of the Death Penalty

The death penalty, or capital punishment, is the use of execution through hanging, beheading, drowning, gas chambers, lethal injection, and electrocution among others in response to a crime. This has spurred much debate on whether it should be used for reasons such as ethics, revenge, economics, effectiveness as a deterrent, and constitutionality. Capital punishment has roots that date back to the 18th century B.C., but, as of 2016, has been abolished in law or practice by more than two thirds of the world’s countries and several states within the United States. Here, the arguments for and against the death penalty are presented and examined for effectiveness. The conclusion is drawn that the death penalty should be abolished and the sentence of life without parole should be adopted as the punishment for capital crimes

Comparing the Violent Crime Trends in Select States to the National Trends to Determine Differences Between Crimes, States, and Regions

Violent crimes include crimes such as murder, rape, robbery, and assault. The FBI in the UCR breaks these down into Type I, crimes against the person, and Type II, property crimes, offenses. The FBI also divides the country into four regions: West, South, Northeast, and Midwest. Each of these regions are examined, through the use of two states from each, here. Their overall violent crime rates and trends, and their specific Type I offensive rates and trends, are examined against the national data and against each other. Several theories are used to explain the potential causes of the differences in crime rates and trends between regions as well as the policy implications for these differences

Linking partial and quasi dynamical symmetries in rotational nuclei

Background: Quasi dynamical symmetries (QDS) and partial dynamical symmetries (PDS) play an important role in the understanding of complex systems. Up to now these symmetry concepts have been considered to be unrelated. Purpose: Establish a link between PDS and QDS and find an emperical manifestation. Methods: Quantum number fluctuations and the intrinsic state formalism are used within the framework of the interacting boson model of nuclei. Results: A previously unrecognized region of the parameter space of the interacting boson model that has both O(6) PDS (purity) and SU(3) QDS (coherence) in the ground band is established. Many rare-earth nuclei approximately satisfying both symmetry requirements are identified. Conclusions: PDS are more abundant than previously recognized and can lead to a QDS of an incompatible symmetry.Comment: 5 pages, 4 figures, 1 tabl

Episodic Nutrient Supply to a Kelp Forest Ecosystem in Southern California

Temporal patterns of nutrient input into a Southern California kelp forest were measured using traditional hydrocast sampling coupled with high frequency temperature profiling. Patterns of nutrient input were related to growth rates of Macrocystis pyrifera located in an adjacent kelp forest. There were 2 distinct components to the pattern of nutrient availability. The long term, or seasonal, component was consistent with large-scale storm-induced mixing and horizontal advection during winter months. In addition, vertical motions of the thermocline, bringing nutrients into the kelp forest, occurred throughout the year with a frequency of about 2 per day and were strongest during the summer months. Weekly hydrocast sampling methods were inadequate for measuring these episodic events, and high frequency sampling was required to resolve the pattern of nutrient input accurately. Although measurable, nutrient input from vertical thermocline motion was inadequate to sustain maximum growth of Macrocystis pyrifera at 10 m depth during the summer months. Thus, the major component of nutrient input came during the winter. These results indicate that nitrate limitation of M. pyrifera is a likely cause of reduced summer growth. Further, high frequency sampling is necessary to predict nutrient availability in nearshore ecosystems dominated by benthic macrophytes where the pattern of nutrient input is dominated by episodic events of short duration

In Situ Growth and Chemical Composition of the Giant Kelp, Macrocystis pyrifera: Response to Temporal Changes in Ambient Nutrient Availability

Temporal variations in growth of the giant kelp Macrocystis pyrifera were examined in relation to ambient nutrient availability and chemical composition of mature blades, the primary site of nutrient and carbohydrate storage in M. pyrifera. The effect of nutrient availability on growth was well approximated by a Monod rectangular hyperbola, with growth saturating at ambient nitrate concentra- tions between 1 and 2 FM. M. pyrlfera was unable to generate nutrient reserves that would last beyond 30 d. Nitrogen reserves were stored as free amino acids, and generally constituted about 10 % of total tissue nitrogen. Total nitrogen content was never more than 2.5% of dry weight. There was no significant correlation between growth and tissue nitrogen. In contrast, carbohydrate levels were negatively correlated with growth rates, tissue nitrogen content, and ambient nutrient availability. Although concentrations of nitrogen and carbohydrate reserves showed familiar variations described for other kelps, the physical environment in southern California is probably not amenable to M. pyrifera making strategic use of these reserves. Nutrient availability appears to be too low to permit accumulation of more than 30 d reserve of nitrogen, and light levels are probably never low enough to make stored carbohydrate reserves necessary for survival

Signatures of Electronic Correlations in Optical Properties of LaFeAsO1−x_{1-x}Fx_x

Spectroscopic ellipsometry is used to determine the dielectric function of the superconducting LaFeAsO$_{0.9}$F$_{0.1}$ ($T_c$ = 27 K) and undoped LaFeAsO polycrystalline samples in the wide range 0.01-6.5 eV at temperatures 10 $\leq T \leq$ 350 K. The free charge carrier response in both samples is heavily damped with the effective carrier density as low as 0.040$\pm$0.005 electrons per unit cell. The spectral weight transfer in the undoped LaFeAsO associated with opening of the pseudogap at about 0.65 eV is restricted at energies below 2 eV. The spectra of superconducting LaFeAsO$_{0.9}$F$_{0.1}$ reveal a significant transfer of the spectral weight to a broad optical band above 4 eV with increasing temperature. Our data may imply that the electronic states near the Fermi surface are strongly renormalized due to electron-phonon and/or electron-electron interactions.Comment: 4 pages, 4 figures, units in Fig.2 adde

Polyelectrolyte-Compression Forces between Spherical DNA Brushes

Optical tweezers are employed to measure the forces of interaction within a single pair of DNA-grafted colloids in dependence of the molecular weight of the DNA-chains, and the concentration and valence of the surrounding ionic medium. The resulting forces are short-range and set in as the surface-to-surface distance between the colloidal cores reaches the value of the brush height. The measured force-distance dependence is analyzed by means of a theoretical treatment based on the compression of the chains on the surface of the opposite-lying colloid. Quantitative agreement with the experiment is obtained for all parameter combinations.Comment: 4 pages, 4 figures, 1 table; manuscript submitted to Phys. Rev. Let

Benthic community metabolism and the role of deposit-feeding callianassid shrimp

In temperate and tropical seas, bioturbation resulting from the burrowing and feeding activities of deposit-feeding callianassid shrimp can have an important impact on the ecosystem. In Gorda Sound, British Virgin Islands, 97 μmol NH4 ˙ m−2 ˙ d−1 and 0.2 μmol PO4 ˙ m−2 ˙ d−1 were released to the water column from burrows of callianassid shrimps (Callianassa rathbunae and Calliax Jonesi). Benthic gross primary production was 288 mg C ˙ m−2 ˙ d−1 and the ratio of gross production to total community 24-hr. respiration was 0.86. The flux of dissolved nutrients released from shrimp burrows could supply less than 5% of the need calculated for benthic primary production, while the net flux from the total benthic community could support 21% of the estimated demand. Stable carbon isotope measurements indicated that these callianassid shrimp derive 100% of their nutritional requirements from benthic microflora