Severe loss of vasopressin-immunoreactive cells in the suprachiasmatic nucleus of aging voles coincides with reduced circadian organization of running wheel activity

Aging leads to a decrease in circadian organization of behavior. Whether this general observation is related to the finding that in older subjects the arginine-vasopressin (AVP) system in the suprachiasmatic nucleus (SCN) has deteriorated is an unsolved question. Here we assessed circadian organization of running wheel behavior and numbers of AVP cells in the SCN of old voles (n=12, 11. 5 months of age) and compared the results with data from young voles (n=16, 4.5 months of age). A third of the young voles, but three-quarter of the old voles lost circadian rhythmicity. Analysis of daily onset to onset periodicity of running wheel activity at the age of 5 and 10 months in individual voles revealed a significant loss of precision of circadian rhythmicity at the higher age. The number of AVP cells in the SCN of old voles decreased substantially, over 78% compared to young voles in general. AVP cell numbers, however, cannot be directly correlated with the state of rhythmicity in old voles; in one of the three circadian rhythmic old voles the SCN contained the least AVP cells. This study does not support the idea of a causal relationship between aging induced reduction in AVP cells in the SCN and the presence of circadian rhythmicity in behavior.     

Positioning and immobilization of individual quantum dots with nanoscale precision

We demonstrate a technique for the precise immobilization of nanoscale objects at accurate positions on two-dimensional surfaces. We have developed a water-based photoresist that causes nanostructures such as colloidal quantum dots to segregate to a thin layer at surfaces. By combining this material with electroosmotic feedback control, we demonstrate the ability to position selected, individual quantum dots at specific locations and to immobilize them with 130 nm precision via localized UV exposure.     

Impregnation of Ni-P metal into polymer substrate via catalyzation in Sc-CO2 and electroless plating in Sc-CO2 emulsion

In this study we investigated the impregnation of Ni-P metal into polymer substrate via catalyzation in supercritical carbon dioxide (Sc-CO₂) and electroless plating in Sc-CO₂ emulsion, in comparison with calculated CO₂ diffusion in polymer on the basis of Fick's law. Sc-CO₂ has two major effects, high diffusivity and good chemical affinity with polymer, on the impregnation of Ni-P metal into the polyimide substrate. Our group fabricated an Ni-P thin film in Sc-CO₂ with an electroless plating emulsion after catalyzing the Sc-CO₂ with Pd complex. According to an EDX analysis, an increase in the Sc-CO₂ catalyzation time led to increases in both the intensity and depth of the Ni-ion penetration into the polyimide. We found that the impregnation reaction of Ni by our novel method is CO₂ diffusion controlling reaction. To clarify which of the two Sc-CO₂ properties, diffusivity or chemical affinity, played a dominant role, we conducted an electroless plating reaction with emulsion using hexane as the catalyzation solvent whose diffusivity is lower than that of Sc-CO₂. The good affinity with polyimide in the hexane catalyzation led to a film fabrication of Ni-P thin films, but numerous cracks were visible on the films under microscopic observation. According to an EDX analysis of the Ni-P catalyzed in hexane, the intensity of the penetrated Ni-ions into the polyimide was very low. The high diffusivity of the Sc-CO₂ promoted the penetration of the Pd catalyst and Ni-P electroless plating solution into the polyimide substrate.     

Identification of coal seams suitability for carbon dioxide sequestration with enhanced coalbed methane recovery: a case study in South Sumatera Basin,Indonesia

Clean Technologies and Environmental Policy - Sequestering carbon dioxide (CO2) with enhanced coalbed methane recovery (ECBM) is a promising clean coal technology in Indonesia, which can reduce CO2...     

Phase control of ultradian feeding rhythms in the common vole (Microtus arvalis): the roles of light and the circadian system

In their ultradian (2- to 3-hr) feeding rhythm, common voles show intraindividual synchrony from day to day, as well as interindividual synchrony between members of the population, even at remote distances. This study addresses the question of how resetting of the ultradian rhythm, a prerequisite for such synchronization, is achieved. Common voles were subjected to short light-dark cycles (1 hr darkness with light varying between 0.7 and 2.5 hr); to T cycles (long light-dark cycles in the circadian range--16 hr darkness and 3-13 hr light); to light pulses (15 min) during different circadian and ultradian phases; and to addition of D2O to the drinking water (25%). Short light-dark cycles and D2O were also applied to voles without circadian rhythmicity, after lesions of the suprachiasmatic nuclei. In these experiments, four hypotheses on synchronization of ultradian rhythmicity were tested: (I) synchronization by a direct response to light; (II) synchronization via the circadian system with multiple triggers, here called "cogs," each controlling a single ultradian feeding bout; and (III and IV) synchronization via the circadian system with a single "cog," which resets an ultradian oscillator and either (III) originates directly from the circadian pacemaker, or (IV) is mediated via the overt circadian activity rhythm. Short light-dark cycles failed to entrain ultradian rhythms, either in circadian-rhythmic or in non-circadian-rhythmic voles; light pulses did not cause phase shifts; and in extreme T cycles no stable phase relationship with light could be demonstrated. Thus, Hypothesis I was rejected. Changes in the circadian period (tau) were generated as aftereffects of light pulses, by entrainment in various T cycles, and by the addition of D2O to the drinking water. These changes in tau did not lead to parallel, let alone proportional, changes in the ultradian period. This excluded Hypothesis II. Both in T-cycle experiments and in the D2O experiments with circadian-rhythmic voles, the phase of ultradian feeding bouts was locked to the end of circadian activity rather than to the most prominent marker of the pacemaker, the onset of circadian activity. This was not expected under Hypothesis III, but was consistent with entrainment via activity (Hypothesis IV). On the basis of these experiments, we conclude that the most likely mechanism of ultradian entrainment is that of a light-insensitive ultradian oscillator, reset every dawn by the termination of the activity phase controlled by the circadian pacemaker, which is itself entrained by the light-dark cycle. Neither in circadian-rhythmic nor in non-circadian-rhythmic voles was the period of the feeding rhythm lengthened by administration of D2O. This insensitivity to deuterium is exceptional among biological rhythms.     

Optical habitats of ultraphytoplankton groups in the Gulf of Eilat (Aqaba), Northern Red Sea

Solar light penetrates deep into the clear water of oligotrophic oceans and may have both beneficial and destructive effects on marine phytoplankton. In oligotrophic waters worldwide, phytoplankton communities consist mostly of ultraphytoplankton of the groups Synechococcus and Prochlorococcus, which differ in their optical properties and, therefore, are better suited for thriving in different niches along the natural vertical light gradient. In this article, we aim to draw the optical boundaries separating the two populations in order to get a better insight into the light-driven dynamics in ultraphytoplankton-community structure and to predict future trends. We report spectral, photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) penetration through the stratified season along with temporal and vertical distributions of Synechococcus and Prochlorococcus in the Gulf of Eilat (Aqaba). These light-field parameters are used to define the apparent limits of the vertical distribution of Synechococcus and Prochlorococcus throughout the water column. Furthermore, we formulate the necessary empirical algorithms, allowing for characterization of the optical habitats defined in this study by remote-sensed or in situ radiometric measurements.     

The Mailman algorithm: A note on matrix-vector multiplication

Given an m×n matrix A we are interested in applying it to a real vector x∈Rn in less than the straightforward O(mn) time. For an exact deterministic computation at the very least all entries in A must be accessed, requiring O(mn) operations and matching the running time of naively applying A to x. However, we claim that if the matrix contains only a constant number of distinct values, then reading the matrix once in O(mn) steps is sufficient to preprocess it such that any subsequent application to vectors requires only O(mn/log(max{m,n})) operations. Algorithms for matrix-vector multiplication over finite fields, which save a log factor, have been known for many years. Our contribution is unique in its simplicity and in the fact that it applies also to real valued vectors. Using our algorithm improves on recent results for dimensionality reduction. It gives the first known random projection process exhibiting asymptotically optimal running time. The mailman algorithm is also shown to be useful (faster than naïve) even for small matrices.     

Routing orderpickers in a warehouse: a comparison between optimal and heuristic solutions

In this paper the problem of finding efficient orderpicking routes is studied for both conventional warehouses, where pickers have a central depot for picking up and depositing carts and pick lists, and modern warehouses, where orderpicking trucks can pick up and deposit pallets at the head of every aisle without returning to the depot. Such environments can be found in many warehouses where paperless picking is performed from pallet locations with pickers having mobile terminals receiving instructions one by one. In order to find orderpicking routes with a minimal length in both the situations of a central depot or decentralized depositing, we extend the well-known polynomial algorithm of Ratliff and Rosenthal [1] that considered warehouses with a central depot. In practice, the problem is mainly solved by using the so-called S-shape heuristic in which orderpickers move in a S-shape curve along the pick locations. The performance of the new algorithm and the S-shape heuristic are compared in three realistic orderpicking systems: (1) narrow-aisle high-bay pallet warehouse; (2) picking in shelf area with decentralized depositing of picked items; and (3) conventional orderpicking from wide-aisle pallet locations. The new algorithm gives a reduction in travel time per route of between 7 and 34%. It turns out that the reduction in travel time strongly depends on the lay-out and operation of the warehouse.