It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

中枢神経系疾患の治療は正常細胞（ニューロン）の機能維持を目的とするが，脳血管障害のように機能障害の原因が細胞の死滅に基づくことは多い．一方，脳腫瘍の治療においては薬物療法や放射線療法といった腫瘍細胞の死滅を目標とするものが大きな位置を占める．いずれの場合にも，細胞死の機序を理解することは各種病態や治療法の理解のうえで重要である．現在のところ最も研究の進んでいる細胞死の型はアポトーシスである．そのなかで重要な位置を占めるミトコンドリアにおける反応および抗アポトーシス因子について概要を紹介する．

Neuroscience 細胞死：最近の知見

Schizophrenia is a heritable brain illness with unknown pathogenic mechanisms. Schizophrenia's strongest genetic association at a population level involves variation in the major histocompatibility complex (MHC) locus, but the genes and molecular mechanisms accounting for this have been challenging to identify. Here we show that this association arises in part from many structurally diverse alleles of the complement component 4 (C4) genes. We found that these alleles generated widely varying levels of C4A and C4B expression in the brain, with each common C4 allele associating with schizophrenia in proportion to its tendency to generate greater expression of C4A. Human C4 protein localized to neuronal synapses, dendrites, axons, and cell bodies. In mice, C4 mediated synapse elimination during postnatal development. These results implicate excessive complement activity in the development of schizophrenia and may help explain the reduced numbers of synapses in the brains of individuals with schizophrenia.

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Schizophrenia risk from complex variation of complement component 4

저작근 근전도에 관한 정상교합자와 ii급 부정교합자의 비교 연구

Our understanding of the cellular implementation of systems-level neural processes like action, thought and emotion has been limited by the availability of tools to interrogate specific classes of neural cells within intact, living brain tissue. Here we identify and develop an archaeal light-driven chloride pump (NpHR) from Natronomonas pharaonis for temporally precise optical inhibition of neural activity. NpHR allows either knockout of single action potentials, or sustained blockade of spiking. NpHR is compatible with ChR2, the previous optical excitation technology we have described, in that the two opposing probes operate at similar light powers but with well-separated action spectra. NpHR, like ChR2, functions in mammals without exogenous cofactors, and the two probes can be integrated with calcium imaging in mammalian brain tissue for bidirectional optical modulation and readout of neural activity. Likewise, NpHR and ChR2 can be targeted together to Caenorhabditis elegans muscle and cholinergic motor neurons to control locomotion bidirectionally. NpHR and ChR2 form a complete system for multimodal, high-speed, genetically targeted, all-optical interrogation of living neural circuits.

Multimodal fast optical interrogation of neural circuitry

The site of action potential generation in unipolar snail neurons was identified by stimulating neurons isolated together with the initial portion of the process from the neuropile. Stimulation consisted of a sinusoidal from electrical current passed along the soma-axonal axis in saline solution. No low threshold sites of action potential generation were found in 80% of test neurons using this technique. Spontaneous activity was determined by the operation of one dominant site on the neuronal process. Antidromic activation of the soma by axonal action potentials (even with simultaneous hyperpolarization of the soma) induced somatic potentials more successfully than direct somatic depolarization by the current flowing through the solution.

Sites of action potential generation in Helix pomatia neurons

During the study of the effect of medic ina l p repa ra t ions on the whole animal o r g a n i s m by means of conventional pha rmaco log ica l methods, i t is usual ly imposs ib le to show the difference between the different groups of medic ines , since only t he i r effect on the convulsive p a r o x y s m is evaluated. It was found that not only c l a s s ical ant iconvulsants , but also a la rge range of o ther medic inal p repa ra t ions , can suppres s or modify epileptic d i s turbances . This applies, in pa r t i cu la r , to the psychot ropic p repa ra t ions , i .e. , t r anqui l i ze r s , neurolept ics , and an t idepressan t s [1-4]. There fo re , the s ea r ch for such expe r imen ta l models , which would make it possible to di f ferent ia te groups of p repa ra t ions with different spec t r a of action and different action mechan i sms , appea r s to be mos t t imely.

Spontaneous activity of mollusk neurons as a model for sampling of anticonvulsants

A two-ray model for multipath fading is described. The model incorporates the effects of the angular structure of the incident signal and is, therefore, potentially suitable for angle diversity applications. The model has four variables. Adjustment of the statistical parameters of these variables makes it possible to match statistics of data obtained from experiments. Through a simulation based on this model, both the single frequency fading and IBPD (inband power difference) statistics of experimental data obtained in Gainesville, FL, for two antennas tilted at different elevation angles have been matched approximately using a single set of parameters. >

A multipath fading model for terrestrial microwave radio

Electrophysiological and morphological studies of a monosynaptic connection are performed on specimens of the isolated CNS of the snail Achatina fulica, using the standard techniques of intracellular leading-off and neuron stimulation and intracellular pressure injection of cobalt chloride. The presence of a monosynaptic connection between two identified neurons is demonstrated both in the physiological experiment and by means of the intracellular dye.

A monosynaptic connection between identified snail neurons.

We examined influence of the β-amyloid peptide (25-35) neurotoxic fragment (βAP) on Helix lucorum food-aversion learning. Testing with aversively conditioned carrot showed that 2, 5, and 14 days after training the βAP-injected group responded in a significantly larger number of cases and with a significantly smaller latency than the sham-injected control group. The results demonstrate that the amyloid peptide partially impairs the learning process. In an attempt to specify what component of memory is impaired we compared responses in a context in which the snails were aversively trained, and in a neutral context. It was found that the sham-injected learned snails significantly less frequently took the aversively conditioned food in the context in which the snails were shocked, while the βAP-injected snails remembered the aversive context 2 days after associative training, but were not able to distinguish two contexts 5, and 14 days after training. In a separate series of experiments a specific context was associated with electric shock, and changes in general responsiveness were tested in two contexts several days later. It was found that the βAP-injected snails significantly increased withdrawal responses in all tested contexts, while the sham-injected control animals selectively increased responsiveness only in the context in which they were reinforced with electric shocks. These results demonstrate that the β-amyloid peptide (25-35) interferes with the learning process, and may play a significant role in behavioral plasticity and memory by selectively impairing only one

Pavel M. Balaban

Papers

Sites of action potential generation in Helix pomatia neurons

Spontaneous activity of mollusk neurons as a model for sampling of anticonvulsants

A multipath fading model for terrestrial microwave radio

A monosynaptic connection between identified snail neurons.

Impairment of Context Memory by β-Amyloid Peptide in Terrestrial Snail