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The study of lattice gauge theories with Monte Carlo simulations is hindered by the infamous sign problem that appears under certain circumstances, in particular at non-zero chemical potential. So far, there is no universal method to overcome this problem. However, recent years brought a new class of non-perturbative Hamiltonian techniques named tensor networks, where the sign problem is absent. In previous work, we have demonstrated that this approach, in particular matrix product states in 1+1 dimensions, can be used to perform precise calculations in a lattice gauge theory, the massless and massive Schwinger model. We have computed the mass spectrum of this theory, its thermal properties and real-time dynamics. In this work, we review these results and we extend our calculations to the case of two flavours and non-zero chemical potential. We are able to reliably reproduce known analytical results for this model, thus demonstrating that tensor networks can tackle the sign problem of a lattice gauge theory at finite density.

A compact Raman lidar has been developed for studying phase changes of water in the atmosphere under the influence of ionization radiation. The Raman lidar is operated at the wavelength of 349 nm and backscattered Raman signals of liquid and vapor phase water are detected at 396 and 400 nm, respectively. Alpha particles emitted from 241Am of 9 MBq ionize air molecules in a scattering chamber, and the resulting ions lead to the formation of liquid water droplets. From the analysis of Raman signal intensities, it has been found that the increase in the liquid water Raman channel is approximately 3 times as much as the decrease in the vapor phase water Raman channel, which is consistent with the theoretical prediction based on the Raman cross-sections. In addition, the radius of the water droplet is estimated to be 0.2 μm.

Abstract Background Transforming growth factor (TGF)-β is known to be produced by progressor tumors and to immobilize dendritic cells (DCs) within those tumors. Moreover, although TGF-β1 has been shown to promote tumor progression, there is still no direct, in vivo evidence as to whether TGF-β1 is able to directly induce distant metastasis. Methods To address that issue and investigate the mechanism by which TGF-β1 suppresses DC activity, we subdermally inoculated mouse ears with squamous cell carcinoma cells stably expressing TGF-β1 or empty vector (mock). Results The numbers of DCs within lymph nodes draining the resultant TGF-β1-expressing tumors was significantly lower than within nodes draining tumors not expressing TGF-β1. We then injected fluorescently labeled bone marrow-derived dendritic cells into the tumors, and subsequent analysis confirmed that the tumors were the source of the DCs within the tumor-draining lymph nodes, and that there were significantly fewer immature DCs within the nodes draining TGF-β1-expressing tumors than within nodes draining tumors not expressing TGF-β1. In addition, 14 days after tumor cell inoculation, lymph node metastasis occurred more frequently in mice inoculated with TGF-β1 transfectants than in those inoculated with the mock transfectants. Conclusions These findings provide new evidence that tumor-derived TGF-β1 inhibits migration of DCs from tumors to their draining lymph nodes, and this immunosuppressive effect of TGF-β1 increases the likelihood of metastasis in the affected nodes.

Abstract Presence of a cervical rib in children is extremely rare, particularly when symptoms of compression of the lower trunk of the brachial plexus occur. We present two cases with such a condition, where two young girls, 11 and 16 years of age were treated by resection of the cervical rib after a supraclavicular exploration of the lower trunk of the brachial plexus. The procedure led to successful results, objectively verified with tests in a work simulator, at one year follow-up.

Abstract Background A delay in surgical nerve repair results in impaired nerve function in humans, but mechanisms behind the weakened nerve regeneration are not known. Activating transcription factor 3 (ATF3) increases the intrinsic growth state of injured neurons early after injury, but the role of long-term changes and their relation to axonal outgrowth after a delayed nerve repair are not well understood. ATF3 expression was examined by immunohistochemistry in motor and sensory neurons and in Schwann cells in rat sciatic nerve and related to axonal outgrowth after transection and delayed nerve repair (repair 0, 30, 90 or 180 days post-injury). Expression of the neuronal cell adhesion molecule (NCAM), which is expressed in non-myelinating Schwann cells, was also examined. Results The number of neurons and Schwann cells expressing ATF3 declined and the length of axonal outgrowth was impaired if the repair was delayed. The decline was more rapid in motor neurons than in sensory neurons and Schwann cells. Regeneration distances over time correlated to number of ATF3 stained neurons and Schwann cells. Many neurofilament stained axons grew along ATF3 stained Schwann cells. If nerve repair was delayed the majority of Schwann cells in the distal nerve segment stained for NCAM. Conclusion Delayed nerve repair impairs nerve regeneration and length of axonal outgrowth correlates to ATF3 expression in both neurons and Schwann cells. Mainly non-myelinating Schwann cells (NCAM stained) are present in distal nerve segments after delayed nerve repair. These data provide a neurobiological basis for the poor outcomes associated with delayed nerve repair. Nerve trunks should, if possible, be promptly repaired.

The neural representation of motion aftereffects induced by various visual flows (translational, rotational, motion-in-depth, and translational transparent flows) was studied under the hypothesis that the imbalances in discharge activities would occur in favor in the direction opposite to the adapting stimulation in the monkey MST cells (cells in the medial superior temporal area) which can discriminate the mode (i.e., translational, rotational, or motion-in-depth) of the given flow. In single-unit recording experiments conducted on anaesthetized monkeys, we found that the rate of spontaneous discharge and the sensitivity to a test stimulus moving in the preferred direction decreased after receiving an adapting stimulation moving in the preferred direction, whereas they increased after receiving an adapting stimulation moving in the null direction. To consistently explain the bidirectional perception of a transparent visual flow and its unidirectional motion aftereffect by the same hypothesis, we need to assume the existence of two subtypes of MST D cells which show directionally selective responses to a translational flow: component cells and integration cells. Our physiological investigation revealed that the MST D cells could be divided into two types: one responded to a transparent flow by two peaks at the instances when the direction of one of the component flow matched the preferred direction of the cell, and the other responded by a single peak at the instance when the direction of the integrated motion matched the preferred direction. In psychophysical experiments on human subjects, we found evidence for the existence of component and integration representations in the human brain. To explain the different motion perceptions, i.e., two transparent flows during presentation of the flows and a single flow in the opposite direction to the integrated flows after stopping the flow stimuli, we suggest that the pattern-discrimination system can select the motion representation that is consistent with the perception of the pattern from two motion representations. We discuss the computational aspects related to the integration of component motion fields.

We studied the LTP inducing factors using temporally and spatially modulated stimuli given to the hippocampal neural network. It was found that when the spatial factors were maintained to be constant the positive correlation in the successive inter-stimulus intervals contributes to produce larger LTP. On the other hand, if the temporal factors are kept constant, the spatial coincidence contributes to produce larger LTP. We propose a learning rule by which these experimental results can be consistently interpreted. Copyright 1996 Elsevier Science Ltd.

Retinal ganglion cells of the cat have been classified physiologically into X-, Y-, and W-cells on the basis of the receptive field properties, and morphologically into alpha-, beta-, and gamma-cells. In order to study directly the correspondence between these classifications, intracellular recordings from the ganglion cells in superfused eye-cup preparations were made with the aid of microelectrodes filled with Lucifer yellow CH. The cells were stained after their photic responses were studied under mesopic adaptation. X-cells, showing sustained depolarization (on-center cells) or hyperpolarization (off-center cells) in response to a spot of light had medium-sized round somata and spread bushy dendrites within a narrow retinal area. On the other hand, on-center and off-center Y-cells, showing transient responses to the spot stimulus, had large somata and widely expanded thick dendrites which were sparsely branched. W-cells which showed weak sustained responses had widely extended thin and winding dendrites, despite a small somal size. These morphological features of Y-, X-, and sustained W-cells correspond well to those of alpha-, beta-, and delta-cells (a subtype of gamma-cells), respectively. The hypothesis of "morphology reflecting function" is strongly supported.

Daily administration of clonidine for 5 weeks (approx. 300 micrograms/kg/day, p.o.) produced significant decreases in blood pressure and renal sympathetic efferent activity in spontaneously hypertensive rats (SHR). After cessation of clonidine administration, blood pressure and sympathetic nerve activity recovered rapidly from the depressed levels to the untreated control levels. These findings could indicate that clonidine-induced hypotension and its rapid recovery to control after withdrawal of clonidine are caused by corresponding changes in sympathetic efferent nerve activity.

1. The dorsal part of medial superior temporal area (MST) has two unique types of visually responsive cells: 1) expansion/contraction cells, which selectively respond to either an expansion or a contraction; and 2) rotation cells, which selectively respond to either a clockwise or a counterclockwise rotation. In addition to selectivity for the mode of motion, both types of cells respond preferentially to movements over a wide field rather than over a small field. With the aim of understanding the underlying mechanisms of these selectivities, we carried out experiments on immobilized monkeys anesthetized with N2O. 2. Expansion/contraction and rotation of a pattern extending over a wide field contain three stimulus factors: 1) the spatial arrangement of different directions of movement, 2) the gradient in the speed of regional movement from the center to the periphery of the stimulus, and 3) the size change of texture components of the pattern in the expansion/contraction and the acceleration of movement of texture components toward the center of the stimulus in the rotation. The contribution of each factor to the activation of the cells was evaluated by comparing the response before and after removing the factor from the stimulus. The moving stimuli that lacked one or two of the factors were produced by the use of a cinematographic animation technique. 3. Withdrawal of the first factor, the spatial arrangement of different directions of movement, reduced the response of both Expansion/contraction and Rotation cells much more severely than either of the other two factors. We concluded that the first factor is far more important for activation than the other two. 4. These results are consistent with the model that Expansion/contraction and Rotation cells receive converging inputs from many directional cells with relatively small receptive fields in different parts of the visual field. Because MST receives strong fiber projections from MT, MT cells are candidates for the input cells. According to the model, if the convergence is organized so that the preferred directions of the input cells are arranged radially, the target cell will be an Expansion/contraction cell; if the input cells are arranged circularly, a Rotation cell will result.