Rest-activity rhythm of the blind mole rat Spalax ehrenbergi under different lighting conditions

The mole rat is a solitary, subterranean and photoperiodic rodent. We investigated its rest activity behavior under several lighting conditions, complemented our observations with light-induced c-fos expression, and compared the activity behavior of two chromosomal forms (2n = 58 and 60). The 26 mole rats had a clear overall preference for activity in the light or dark period, but prolonged recordings in five individuals showed that the initial preference was not stable in the nocturnal animals, they became diurnal. A 6-h advance of the light-dark (LD) cycle induced a shift of activity and the previous LD preference was reestablished. The large daily variability of activity onset did not allow this study to determine whether the animals were entrained to the LD cycle upon release into constant darkness (DD) or whether activity had been masked by light. The period of the motor activity rhythm in DD free ran in more than 50% of the animals. No differences in activity were observed between the two karyotypes. Immunohistochemistry for c-fos expression in the nucleus suprachiasmaticus at different circadian times showed that c-fos was induced only in animals exposed to a 1-h light pulse during the subjective night, but not during the subjective day or in control animals in the absence of a light pulse. The large intra- and inter-individual variability in daily motor activity both in LD and in DD suggest only a weak photic entrainment of the circadian clock to light of approximately 100 lux, and possibly a weak regulation of behavior by the circadian clock.     

Disseminated intravascular coagulation in association with the delayed rejection of pig-to-baboon renal xenografts

BACKGROUND: Intravascular fibrin deposition and platelet sequestration occur with porcine xenograft rejection by baboons. Disseminated intravascular coagulopathy may arise either as a direct consequence of the failure to fully deplete xenoreactive natural antibodies and block complement, or because of putative cross-species molecular incompatibilities in this discordant species combination. METHODS: Three baboons were conditioned with retrovirally transduced autologous bone marrow to induce tolerance to swine antigens. Xenoreactive natural antibodies and complement were depleted by plasmapheresis and the use of Gal alpha1-3Gal column adsorptions; baboons were then splenectomized and underwent renal xenografting from inbred, miniature pigs. Soluble complement receptor type-1 with protocol immunosuppression (mycophenolate mofetil, 15-deoxyspergualin, steroids, and cyclosporine) was administered. RESULTS: A bleeding diathesis was clinically evident from days 5 to 12 after transplantation in two baboons. Low levels of circulating C3a, C3d, and iC3b were measured despite the absence of functional circulating complement components. Profound thrombocytopenia with abnormalities in keeping with disseminated intravascular coagulopathy were observed. Prolongation of prothrombin and partial thromboplastin times was accompanied by evidence for tissue factor-mediated coagulation pathways, high levels of thrombin generation (prothrombin fragment F(1+2) production and thrombin-antithrombin complex formation), fibrinogen depletion, and production of high levels of the fibrin degradation product D-dimer. Importantly, these disturbances resolved rapidly after the excision of the rejected xenografts in two surviving animals. Histopathological examination of the rejected xenografts confirmed vascular injury, fibrin deposition, platelet deposition, and localized complement activation. CONCLUSIONS: Systemic coagulation disturbances are associated with delayed xenograft rejection.     

Unfair comparisons.

Suggests that when organizational researchers competitively test 2 or more theories, or compare the predictive or relational strength of 2 or more factors or variables, the results can lead them to conclude that one theory or variable is stronger than the other(s). It is argued that such conclusions can be insensitive to a potential alternative explanation of the results: The stronger theory, factor, or variable was favored by being more strongly operationalized, manipulated, or measured. This can render the comparative study into a test of a poorly framed empirical question, the results of which are at least partial artifacts of the procedures, manipulations, or measures used. Four illustrations of this alternative explanation of comparative results are drawn from recent manipulation-based (disadvantaged theories due to procedural nonequivalence and unclear comparisons of factors due to unassessed distributional equivalence) and measurement-based (disadvantaged variables due to procedural nonequivalence and to procedural and distributional nonequivalence) studies of organizational behavior. Generic procedures are described than can make for fairer comparisons. Some possible points of misunderstanding regarding the authors' arguments (e.g., all differential support is artifactual) are addressed. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exponential error bounds for coding through noisy channels withinaccurately known statistics and for generalized decision rules

Generalized decoding decision rules provide added flexibility in a decoding scheme, and some advantages. In a generalized decoding decision rule, the following possibilities are considered: (1) the decoder has the option of not deciding at all, or rejecting all estimates. This is termed an erasure; (2) the decoder has the option of putting out more than one estimate. The resulting output is called a list. Only if the correct codeword is not on the list is there a list error. Taking into account the lack of exact knowledge of the channel statistics and assuming a mismatch between the true channel transition probabilities and the nominal probabilities used in the decoding metric, error bounds are developed for generalized decision rules. Conditions under which the error probabilities converge to zero exponentially with the block length, in spite of the presence of mismatch, are established     

A review of bistatic k-space imaging for electromagnetic predictioncodes for scattering and antennas

A bistatic k-space imaging concept for frequency-domain (FD) electromagnetic (EM) computer codes is presented. The concept enables the computation of images without the frequency sweep required for experimental images, resulting in a significant reduction in computational effort. This analytical imaging technique uses bistatic radiation computed from a generalized radiation integral. Images permit physical insight and understanding into how a radiation or scattering pattern is produced, by decomposition of the resultant radiation into contributions from localized scattering centers, or hot spots. Knowledge of these hot spots permits a user to understand and modify the structure to obtain desired features     

Operations and maintenance centre — delivering network services

Network management, administration and maintenance activities have developed dramatically since the introduction of digital exchanges, with their ever-increasing capabilities for remote interrogation and control. The operations and maintenance centre (OMC) was born to exploit the exchange capabilities and fulfil the need for fast and efficient centralised administration and maintenance facilities. This paper describes and traces the development of the OMC, outlines its key role and achievements in the delivery of network services in pace with on-going requirements, and investigates the technical challenges being addressed as part of its evolutionary design.     

Poliomyelitis-like illness due to Japanese encephalitis virus

BACKGROUND: Acute flaccid paralysis remains common among Vietnamese children despite a pronounced fall in the incidence of poliomyelitis. METHODS: During 1995, all 22 children presenting with acute flaccid paralysis to a referral centre in Ho Chi Minh City, Vietnam, had virological cultures and antibody measurements done on serum, cerebrospinal fluid, and faeces. A year later the children were reassessed and electrophysiological studies were done. FINDINGS: Wild poliovirus type 1 was isolated from the faeces of only one patient, and non-polio enteroviruses from three patients. 12 (55%) of the 22 children with acute flaccid paralysis had evidence of acute Japanese encephalitis virus (JEV) infection, compared with only one (1%) of 88 age-matched hospital controls (children with diphtheria; p<0.0001). Compared with JEV-negative patients, weakness in JEV-infected children was more rapid in onset, tended to be asymmetrical, but was less likely to involve the arms. All 12 children with JEV infection were febrile at the onset of weakness, seven had acute retention of urine, and ten had CSF pleiocytosis. Seven of eight JEV-negative patients met the case-definition of Guillain-Barré syndrome, compared with only one of 12 JEV-positive children. At follow-up, patients with JEV infection had greater disability and were more likely to have muscle wasting than were JEV-negative children. Nerve conduction and electromyographic studies indicated damage to the anterior horn cells. INTERPRETATION: JEV causes an acute flaccid paralysis in children that has similar clinical and pathological features to poliomyelitis. In endemic areas, children with acute flaccid paralysis should be investigated for evidence of JEV infection.