California State University, Long Beach

About: California State University, Long Beach is a education organization based out in Long Beach, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 10036 authors who have published 13933 publications receiving 377394 citations. The organization is also known as: Cal State Long Beach & Long Beach State.

Phytogenesis of halomethanes: a product of selection or a metabolic accident?

Abstract: Phytoplankton (microalgae), seaweeds(macroalgae), higher plants and fungi producehalomethanes. Algae and fungi produce bothmethyl halides and polyhalomethanes, whereasplants are known to produce only methylhalides. Why these organisms producehalomethanes is a question frequently asked bychemists and biologists. This question impliesthat halomethanes have a function and have aselective value to the producing organism.Except for some fungi, the evolutionaryadvantage of producing halomethanes may notpresently exist. Polyhalomethanes areby-products of halogenation of certain organiccompounds by haloperoxidases in marine algaeand perhaps some fungi, and they may beindirectly produced in aquatic environments byalgal release of oxidized halogen species. Amain function of this enzyme is to rid the cellof harmful oxidants such as hydrogen peroxide.Monohalomethanes (methyl halides) are productsof methyltransferase activity. It has beenproposed that methyl halide production mayprovide a mechanism to regulate chloride levelsin halotolerant plants. The examination of halidecellular concentrations, halomethane productionrates, and enzyme characteristics raisesquestions about this possible function. Inalgae, plants and some fungi, methyl halidesmay be a result of the insertion of ubiquitoushalides into the active site of numerousmethyltransferases. Therefore, halomethanes maybe by-products or `accidents' of metabolism.

Olmec Pottery Production and Export in Ancient Mexico Determined Through Elemental Analysis

Abstract: The first Mesoamerican civilization, the Gulf Coast Olmec, is associated with hierarchical society, monumental art, and an internally consistent ideology, expressed in a distinct style and salient iconography. Whether the Olmec style arose in just one area or emerged from interactions among scattered contemporaneous societies remains controversial. Using elemental analysis, we determined the regional clay sources of 725 archaeological ceramic samples from across Mesoamerica. Exported Olmec-style ceramics originated from the San Lorenzo region of the Gulf Coast, supporting Olmec priority in the creation and spread of the first unified style and iconographic system in Mesoamerica.

Ultrafast conductivity dynamics in colossal magnetoresistance manganites.

Abstract: Ultrafast picosecond measurements of optically induced changes in the absolute conductivity (0.4–1.0 THz) of La0.7M0.3MnO3 thin films (M Ca, Sr) from 10 K to 0.9Tc reveal a two-component relaxation. A fast, 2 ps, conductivity decrease arises from an optically induced modification of the effective phonon temperature. The slower component, related to spin-lattice relaxation, has a lifetime that increases upon approaching Tc from below in accordance with an increasing spin specific heat. We show that, for T o Tc, ≠s≠T is primarily determined by thermally disordered phonons while spin fluctuations dominate near Tc. The observation of “colossal” negative magnetoresistance (CMR) in the hole-doped manganite perovskites (R12xDxMnO3, where, e.g., R La, Nd and D Ca, Sr) demonstrates the sensitivity of electronic conduction to the underlying magnetic structure in these materials [1,2]. Experimental and theoretical work has also revealed the importance of the lattice and orbital degrees of freedom in determining the electronic properties of CMR materials above and below Tc [3,4]. Nonetheless, it is still not clear, especially for T o Tc, what the relative importance of phonons is in comparison to double exchange in determining s. Ultrafast optical spectroscopy has provided significant insight into electron dynamics in metals [5–7], and more recently, transition metal oxides [8 –10]. Using similar ultrafast techniques, we address the relative contributions of spin fluctuations and phonons in determining the conductivity in the manganites from 10 Kt o0.9Tc. Terahertz time-domain spectroscopy is an ultrafast optical technique in which electric field transients are used to measure the complex conductivity of a material. Since this is a coherent technique, a sample can be optically excited and then probed with a terahertz (THz) pulse to measure induced conductivity changes with picosecond (ps) resolution. We use this method, known as timeresolved terahertz spectroscopy (TRTS), to measure ps conductivity transients in La0.7Ca0.3MnO3 (LCMO) and La0.7Sr0.3MnO3 (LSMO) thin films. The dynamics occur on two time scales. A fast, 2 ps, conductivity decrease arises from optically induced modification of the effective phonon temperature. The slower component, related to spin-lattice relaxation, has a lifetime that increases upon approaching Tc from below in accordance with an increasing spin specific heat. Our results demonstrate that, at low temperatures, ≠s≠T is primarily determined by thermally disordered phonons while spin fluctuations dominate close to Tc. The TRTS experiments were performed on LCMO and LSMO epitaxial thin films grown on LaAlO3 substrates using pulsed laser deposition [11]. For very thin films (150 A), island growth can alter the film properties, but the thicker films used in these experiments (1000 A) display bulk behavior [12]. Magnetization measurements

Diel movement patterns of the scalloped hammerhead shark (Sphyrna lewini) in relation to El Bajo Espiritu Santo: a refuging central-position social system

Abstract: Movement patterns of scalloped hammerhead sharks in the vicinity of El Bajo Espiritu Santo, a seamount in the Gulf of California, were determined by tracking by ultrasonic telemetry 13 sharks and marking 100 sharks. The 13 tracked sharks swam back and forth along the seamount ridge throughout the day. They did not swim in different directions to reduce swimming effort when currents changed from a parallel to a perpendicular orientation to the ridge. Sharks tracked up to 8 km away into the pelagic environment soon returned to the seamount. From such trackings and repeated observations of marked sharks over periods of several weeks, it is believed that most sharks disperse and return to the seamount in a rhythmical fashion. The separate departures of individual hammerheads in five paired trackings indicated that the sharks left the seamount either in small groups or singly. For these reasons, we argue that the social system of the scalloped hammerhead shark can be described as a refuging system.

The structure of interpersonal trust in the workplace.

Abstract: The importance of each of five underlying interpersonal trust components (competence, consistency, integrity, loyalty, and openness) as they affect trust among supervisors, subordinates, and peers ...