Avoiding deontic explosion by contextually restricting aggregation

In this paper, we present an adaptive logic for deontic conflicts, called P2.1(r), that is based on Goble's logic SDLaPe-a bimodal extension of Goble's logic P that invalidates aggregation for all prima facie obligations. The logic P2.1(r) has several advantages with respect to SDLaPe. For consistent sets of obligations it yields the same results as Standard Deontic Logic and for inconsistent sets of obligations, it validates aggregation "as much as possible". It thus leads to a richer consequence set than SDLaPe. The logic P2.1(r) avoids Goble's criticisms against other non-adjunctive systems of deontic logic. Moreover, it can handle all the 'toy examples' from the literature as well as more complex ones

Thermal Radiation Analysis System (TRASYS)

A user's manual is presented for TRASYS, which is a digital software system with a generalized capability for solving radiation problems. Subroutines, file, and variable definitions are presented along with subroutine and function descriptions for the preprocessor. Definitions and descriptions of components of the processor are also presented

PRELUDE TO SEVEN SLOTS: FILLING AND SUBSEQUENT MODIFICATION OF SEVEN BROAD CANYONS IN THE NAVAJO SANDSTONE, SOUTH-CENTRAL UTAH

Within a four square kilometer portion of Grand Staircase-Escalante National Monument, seven distinct slot canyons cut the Jurassic Navajo Sandstone. Four of the slots developed along separate reaches of a trunk stream (Dry Fork of Coyote Gulch), and three (including canyons locally known as “Peekaboo” and “Spooky”) are at the distal ends of south-flowing tributary drainages. All these slot canyons are examples of epigenetic gorges—bedrock channel reaches shifted laterally from previous reach locations. The previous channels became filled with alluvium, allowing active channels to shift laterally in places and to subsequently re-incise through bedrock elsewhere. New evidence, based on optically stimulated luminescence (OSL) ages, indicates that this thick alluvium started to fill broad, pre-existing, bedrock canyons before 55,000 years ago, and that filling continued until at least 48,000 years ago. Streams start to fill their channels when sediment supply increases relative to stream power. The following conditions favored alluviation in the study area: (1) a cooler, wetter climate increased the rate of mass wasting along the Straight Cliffs (the headwaters of Dry Fork) and the rate of weathering of the broad outcrops of Navajo and Entrada Sandstone; (2) windier conditions increased the amount of eolian sand transport, perhaps destabilizing dunes and moving their stored sediment into stream channels; and (3) southward migration of the jet stream diminished the frequency and severity of convective storms. We hypothesize that a subsequent increase in the frequency of intense runoff events after 48 ka, combined with the diversion of flow over steep but unchannelized bedrock surfaces, led to a brief and unusual episode of rapid canyon cutting. This work illustrates a specific mechanism by which climate change can induce river incision, and conversely how information on climate may be recorded in the morphology of erosional landscapes

Bose-Einstein condensation as symmetry breaking in compact curved spacetimes

We examine Bose-Einstein condensation as a form of symmetry breaking in the specific model of the Einstein static universe. We show that symmetry breaking never occursin the sense that the chemical potential $\mu$ never reaches its critical value.This leads us to some statements about spaces of finite volume in general. In an appendix we clarify the relationship between the standard statistical mechanical approaches and the field theory method using zeta functions.Comment: Revtex, 25 pages, 3 figures, uses EPSF.sty. To be published in Phys. Rev.

Temporal and spatial variability in dune reactivation across the Nebraska Sand Hills, USA

The Nebraska Sand Hills is a stabilized dune field on the Great Plains of North America. Although it is well known that this dune field, like several others on the Great Plains, last experienced widespread activity during the Medieval Climatic Anomaly (MCA, ~AD 900–1300), spatial variation in the timing and nature of drought development is poorly constrained. To elucidate spatial trends in dune reactivation, samples potentially representing MCA activity across the Sand Hills were collected and dated using optically stimulated luminescence (OSL). Ages from the older part of the MCA were obtained from eolian sediments in the northwestern Sand Hills, while ages from later in the episode were obtained to the southeast, suggesting a geographic trend in the timing of revegetation of the dunes near the end of the drought. Revegetation likely occurred to the northwest initially as a result of renewed moisture availability from a rising water table in the interdunes, which serve as refugia for vegetation during times of drought. Vegetation then gradually spread to the southeastern Sand Hills. An additional spatial trend in ages is apparent in the chronology of linear dune mobilization across the Sand Hills. Linear dunes in the northwest are superimposed on megadunes and originated during the last reactivation, while linear dunes in the southeast are built around older cores of dunes and formed during several reactivations. Our geochronology reveals three episodes of eolian transport, including the MCA, in the formation of linear dunes in the southeast

8000 years of environmental evolution of barrier–lagoon systems emplaced in coastal embayments (NW Iberia)

The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and vulnerable, small and shallow barrier– lagoon systems structurally controlled. The case study was selected to analyse barrier–lagoon evolution based on detailed sedimentary architecture, chronology, geochemical and biological proxies. The main objective is to test the hypothesis of structural control and the significance at regional scale of any highenergy event recorded. This work is also aimed at identifying general patterns and conceptualizing the formation and evolution of this type of coastal systems. The results allowed us to establish a conceptual model of Holocene evolution that applies to rock-bounded barrier–lagoon systems. The initial stage (early Holocene) is characterized by freshwater peat sedimentation and ended by marine flooding. The timing of the marine flooding depends on the relation between the elevation of the basin and the relative mean sea-level position; the lower the topography, the earlier the marine inundation. Thus, the age of basin inundation ranged from 8 to 4 ka BP supporting significant structural differences. Once marine inundation occurred, all systems followed similar evolutionary patterns characterized by a phase of landward barrier migration and aeolian sedimentation towards the back-barrier (i.e. retrogradation) that extended circa 3.5 ka BP. The later phases of evolution are characterized by a general trend to the stabilization of the barriers and the infilling of the lagoons. This stabilization may be temporally interrupted by episodes of enhanced storminess or sediment scarcity. In this regard, washover deposits identified within the sedimentary architecture of the case study explored here suggest pervasive high-energy events coeval with some of the cooling events identified in the North Atlantic during the mid- to late Holocene

8000 years of environmental evolution of barrier–lagoon systems emplaced in coastal embayments (NW Iberia)

The rocky and indented coast of NW Iberia is characterized by the presence of highly valuable and vulnerable, small and shallow barrier– lagoon systems structurally controlled. The case study was selected to analyse barrier–lagoon evolution based on detailed sedimentary architecture, chronology, geochemical and biological proxies. The main objective is to test the hypothesis of structural control and the significance at regional scale of any highenergy event recorded. This work is also aimed at identifying general patterns and conceptualizing the formation and evolution of this type of coastal systems. The results allowed us to establish a conceptual model of Holocene evolution that applies to rock-bounded barrier–lagoon systems. The initial stage (early Holocene) is characterized by freshwater peat sedimentation and ended by marine flooding. The timing of the marine flooding depends on the relation between the elevation of the basin and the relative mean sea-level position; the lower the topography, the earlier the marine inundation. Thus, the age of basin inundation ranged from 8 to 4 ka BP supporting significant structural differences. Once marine inundation occurred, all systems followed similar evolutionary patterns characterized by a phase of landward barrier migration and aeolian sedimentation towards the back-barrier (i.e. retrogradation) that extended circa 3.5 ka BP. The later phases of evolution are characterized by a general trend to the stabilization of the barriers and the infilling of the lagoons. This stabilization may be temporally interrupted by episodes of enhanced storminess or sediment scarcity. In this regard, washover deposits identified within the sedimentary architecture of the case study explored here suggest pervasive high-energy events coeval with some of the cooling events identified in the North Atlantic during the mid- to late Holocene

Conversion From Tacrolimus to Belatacept to Prevent the Progression of Chronic Kidney Disease in Pancreas Transplantation: Case Report of Two Patients

Belatacept is a novel immunosuppressive agent that may be used as an alternative to calcineurin inhibitors (CNI) in immunosuppression (IS) regimens. We report two cases of pancreas transplant that were switched from tacrolimus (TAC) to belatacept. Case 1: 38‐year‐old female with pancreas transplant alone maintained on TAC‐based IS regimen whose serum creatinine (SCr) slowly deteriorated from 0.6 mg/dL at baseline to 2.2 mg/dL, 16 months posttransplant. A native kidney biopsy performed showed CNI toxicity. The patient was started on belatacept and TAC was eliminated. Case 2: 49‐year‐old female with simultaneous pancreas–kidney transplant, maintained on TAC‐based regimen where the SCr worsened over an initial 3‐month period from a baseline of 1.0 to 3.0 mg/dL. Belatacept was started and TAC was lowered. Due to persistent graft dysfunction and kidney transplant biopsy still showing changes consistent with CNI toxicity, the TAC was then discontinued. At >1 year postbelatacept and off TAC follow‐up, kidney function as measured by SCr remains stable at 1.0 ± 0.2 mg/dL in both recipients. Neither patient developed rejection following the switch, and pancreas allograft function remains stable in both recipients

Thermodynamic aspects of materials' hardness: prediction of novel superhard high-pressure phases

In the present work we have proposed the method that allows one to easily estimate hardness and bulk modulus of known or hypothetical solid phases from the data on Gibbs energy of atomization of the elements and corresponding covalent radii. It has been shown that hardness and bulk moduli of compounds strongly correlate with their thermodynamic and structural properties. The proposed method may be used for a large number of compounds with various types of chemical bonding and structures; moreover, the temperature dependence of hardness may be calculated, that has been performed for diamond and cubic boron nitride. The correctness of this approach has been shown for the recently synthesized superhard diamond-like BC5. It has been predicted that the hypothetical forms of B2O3, diamond-like boron, BCx and COx, which could be synthesized at high pressures and temperatures, should have extreme hardness

Photon-Photon Scattering, Pion Polarizability and Chiral Symmetry

Recent attempts to detect the pion polarizability via analysis of $\gamma\gamma\rightarrow\pi\pi$ measurements are examined. The connection between calculations based on dispersion relations and on chiral perturbation theory is established by matching the low energy chiral amplitude with that given by a full dispersive treatment. Using the values for the polarizability required by chiral symmetry, predicted and experimental cross sections are shown to be in agreement.Comment: 21 pages(+10 figures available on request), LATEX, UMHEP-38