Towards intuitionistic dynamic logic

We propose the beginnings of an intuitionistic propopsitional dynamic logic, and describe several serious open problems

Nuclear spin relaxation induced by a mechanical resonator

We report on measurements of the spin lifetime of nuclear spins strongly coupled to a micromechanical cantilever as used in magnetic resonance force microscopy. We find that the rotating-frame correlation time of the statistical nuclear polarization is set by the magneto-mechanical noise originating from the thermal motion of the cantilever. Evidence is based on the effect of three parameters: (1) the magnetic field gradient (the coupling strength), (2) the Rabi frequency of the spins (the transition energy), and (3) the temperature of the low-frequency mechanical modes. Experimental results are compared to relaxation rates calculated from the spectral density of the magneto-mechanical noise.Comment: 4 pages, 4 figure

Feedback cooling of a cantilever's fundamental mode below 5 mK

We cool the fundamental mechanical mode of an ultrasoft silicon cantilever from a base temperature of 2.2 K to 2.9 +/- 0.3 mK using active optomechanical feedback. The lowest observed mode temperature is consistent with limits determined by the properties of the cantilever and by the measurement noise. For high feedback gain, the driven cantilever motion is found to suppress or "squash" the optical interferometer intensity noise below the shot noise level.Comment: 4 pages, 6 figure

THE Pb AND Cd CONCENTRATIONS IN MANGROVE SUBSTRATE OF AMBON BAY

The mangrove ecosystem is one of the potential coastal ecosystems in Ambon Bay waters, most of which are in Inner Ambon Bay.Threats to the mangrove ecosystem in the waters of Ambon Bay are the activities that take place around it. Moreover, several rivers that empty into Ambon Bay cause the entry of debris/waste from land. Previous studies have shown that Pb and Cd have been detected in seawater in Ambon Bay waters, so it is considered important to conduct research on mangrove ecosystem sediments. The purpose of this study was to determine the concentration of heavy metals (Pb and Cd) in sediments in the mangrove ecosystem of Ambon Bay. The sampling points of the sediment in mangrove ecosystems were carried out using purposive sampling method. Sample analysis was carried out at the Environmental Productivity Laboratory of IPB using the Nitric Acid-Perchloric Acid Digestion method. The results showed that the concentration of heavy metal Plumbum (Pb) ranged from 18.25-35.98 mg/kg and Cadmium (Cd) 1.57-2.70 mg/kg. The results showed that the concentration of heavy metal Plumbum (Pb) ranged from 18.25-35.98 mg/kg and Cadmium (Cd) 1.57-2.70 mg/kg. Based on the results of the analysis, it can be said that, although Pb was found in fairly high concentrations, it had not yet exceeded the toxic threshold, while Cd had approached the toxic threshold. Overall, it can be concluded that the sediment has been contaminated with heavy metals Pb and Cd but has not affected the mangrove ecosystem, and is an indication that natural filtration occurs.Salah satu potensi ekosistem pesisir yang cukup luas ada di perairan Teluk Ambon Dalam adalah ekosistem mangrove. Ancaman bagi ekosistem mangrove yang ada di perairan Teluk Ambon adalah aktivitas yang berlangsung di sekitarnya (antropogenik). Adanya beberapa sungai yang bermuara di Teluk Ambon menjadi pendukung masuknya buangan/limbah dari darat. Logam berat Pb dan Cd telah terdeteksi pada air laut di perairan Teluk Ambon, sehingga dianggap penting untuk melakukan penelitian pada sedimen ekosistem mangrove. Tujuan dari penelitian ini adalah untuk mengetahui konsentrasi logam berat (Pb dan Cd) dalam sedimen pada ekosistem mangrove Teluk Ambon. Penentuan titik pengambilan sampel sedimen pada ekosistem mangrove dilakukan dengan menggunakan metode purposive sampling. Analisis sampel dilakukan dengan menggunakan metode Nitric Acid-Perchloric Acid Digestion. Hasil penelitian menunjukkan bahwa konsentrasi logam berat Plumbum (Pb) berkisar antara 18,25-35,98 mg/kg dan Cadmium (Cd) 1,57-2,70 mg/kg. Hasil analisis menunjukkan bahwa, Pb walaupun didapati dalam konsentrasi yang cukup tinggi namun belum melampaui ambang batas toksik, sementara Cd telah mendekati ambang batas toksik. Secara keseluruhan dapat disimpulkan bahwa, sedimen telah terkontaminasi logam berat Pb dan Cd namun belum berpengaruh pada ekosistem mangrove, dan merupakan indikasi bahwa terjadi filtrasi alami. &nbsp

Molecular immunophenotyping of lungs and spleens in naive and vaccinated chickens early after pulmonary avian influenza A (H9N2) virus infection

In a respiratory-infection-model with the avian influenza A H9N2 virus we studied lung and splenic immune reactions in chickens using a recently developed 5K chicken immuno-microarray. Groups of chickens were either mock-immunized (referred to as non-immune), vaccinated with inactivated viral antigen only (immune) or with viral antigen in a water-in-oil (W/O) immunopotentiator (immune potentiated). Three weeks after vaccination all animals were given a respiratory infection. Immune potentiated birds developed inhibitory antiviral antibodies, showed minimal lung histopathology and no detectable viral sequences, while non-immune animals showed microscopic immunopathology and detectable virus. Immune birds, receiving antigen in saline only, showed minimal microscopic histopathology, and intermediate levels of virus detection. These classical features in the different groups were mirrored by overlapping or specific mRNA gene expression profiles in lungs and spleen using microarray analysis. To our knowledge this is the first study demonstrating pneumonia-associated lung pathology of the low pathogenic avian influenza H9N2 virus. Our data provide insights into the molecular interaction of this virus with its natural host when naive or primed by vaccination

A special irreducible matrix representation of the real Clifford algebra C(3,1)

4x4 Dirac (gamma) matrices (irreducible matrix representations of the Clifford algebras C(3,1), C(1,3), C(4,0)) are an essential part of many calculations in quantum physics. Although the final physical results do not depend on the applied representation of the Dirac matrices (e.g. due to the invariance of traces of products of Dirac matrices), the appropriate choice of the representation used may facilitate the analysis. The present paper introduces a particularly symmetric real representation of 4x4 Dirac matrices (Majorana representation) which may prove useful in the future. As a byproduct, a compact formula for (transformed) Pauli matrices is found. The consideration is based on the role played by isoclinic 2-planes in the geometry of the real Clifford algebra C(3,0) which provide an invariant geometric frame for it. It can be generalized to larger Clifford algebras.Comment: 23 pages LaTeX, to appear in the J. Math. Phys. (v2: appendix B on Pauli matrices and references are added, minor other changes

Observations of Time-Dependent Behavior in the Two-Layer Rayleigh-Benard System

In this paper we present results from experiments with a system consisting of two immiscible fluid layers in rectangular and annular geometries, driven by a vertical temperature gradient. Time-dependent variations in the type of coupling observed between the two layers are described and characterized

Perplexity – a new predictor of cognitive changes in spoken language? – results of the Interdisciplinary Longitudinal Study on Adult Development and Aging (ILSE)

Abstract: In addition to memory loss, progressive deterioration of speech and language skills is among the main symptoms at the onset of Alzheimer’s disease (AD) as well as in mild cognitive impairment (MCI). Detailed interview analyses demonstrated early symptoms years before the onset of AD/MCI. Automatic speech processing could be a promising approach to identifying underlying mechanisms in larger studies or even support diagnostics. Perplexity as a measure of predictability of text could be a sensitive indicator of cognitive deterioration. Therefore, voice recordings from the Interdisciplinary Longitudinal Study on Adult Development and Aging were analyzed with regard to neuropsychological parameters in participants that develop MCI/AD or remain cognitively healthy. Preliminary results indicate that perplexity predicts severity of cognitive deficits and information processing speed obtained 10–12 years later in participants who developed MCI/AD in contrast to those who stayed healthy. Findings support the heuristic value of research on the diagnostic potential of automatic speech processing

Force-detected nuclear magnetic resonance: Recent advances and future challenges

We review recent efforts to detect small numbers of nuclear spins using magnetic resonance force microscopy. Magnetic resonance force microscopy (MRFM) is a scanning probe technique that relies on the mechanical measurement of the weak magnetic force between a microscopic magnet and the magnetic moments in a sample. Spurred by the recent progress in fabricating ultrasensitive force detectors, MRFM has rapidly improved its capability over the last decade. Today it boasts a spin sensitivity that surpasses conventional, inductive nuclear magnetic resonance detectors by about eight orders of magnitude. In this review we touch on the origins of this technique and focus on its recent application to nanoscale nuclear spin ensembles, in particular on the imaging of nanoscale objects with a three-dimensional (3D) spatial resolution better than 10 nm. We consider the experimental advances driving this work and highlight the underlying physical principles and limitations of the method. Finally, we discuss the challenges that must be met in order to advance the technique towards single nuclear spin sensitivity -- and perhaps -- to 3D microscopy of molecules with atomic resolution.Comment: 15 pages & 11 figure