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Use of near infrared instead of visible light would markedly improve tissue penetration, making larger tumors candidates for PDT. Since common photosensitizers exhibit virtually no absorption in this wavelength region, conditions are required where the simultaneous action of two photons is possible. Healthy tissue (rat ears), sensitized by hematoporphyrin derivative, sulfonated chloroaluminium phthalocyanine (CIBA-GEIGY) or pheophorbide a (PORPHYRIN PRODUCTS), was irradiated (1064 nm, 10 nsec) with power densities up to 200 MWcm-2and energy densities up to 200 kJcm-2. No reproducible photodynamic lesions were observed, but there was a strong sensitizer fluorescence which depended quadratically on the excitation intensity. This may be useful to determine the tissue sensitizer concentration to an otherwise inaccessible depth.

Dynamical issues associated with quantum fields in Rindler space are addressed in a study of the interaction between two sources at rest generated by the exchange of scalar particles, photons, and gravitons. These static interaction energies in Rindler space are shown to be scale invariant, complex quantities. The imaginary part will be seen to have its quantum mechanical origin in the presence of an infinity of zero modes in uniformly accelerated frames which in turn are related to the radiation observed in inertial frames. The impact of a uniform acceleration on the stability of matter and the properties of particles is discussed, and estimates are presented of the instability of hydrogen atoms when approaching the horizon. [ABSTRACT FROM AUTHOR]

Zusammenfassung: Ziel der Arbeit war es, die Nährstoffverlagerung durch das im Erwerbsobstbau übliche Grasmulchsystem von der Fahrgasse in den Baumstreifen im Rahmen nachhaltiger Nährstoffkreisläufe zu berechnen. Dies wurde in den Jahren 1995 (5  Mähdurchgänge) und 1996 (3  Mähdurchgänge) bei der Sorte ‘Gloster’ auf M9 mit 4 m × 1,5 m Pflanzabstand im Nachbau im Rahmen eines bei der DFG akkreditierten, 40  Jahre dauernden Dauerdüngungsversuches in Klein-Altendorf an der Universität Bonn untersucht. Um die Menge und Bestandteile der verlagerten Grasmahd zu bestimmen, wurden Folien auf den Baumstreifen ausgelegt. Mit dem Grasmulch wurden 550 kg (ungedüngt) und 800 kg (gedüngt) TM (Trockenmasse) pro  ha und Jahr bei 5-maligem Mähen 1995 in den Baumstreifen verlagert, dies entspricht ca.  40% der Grasmahd bei einer Schnitthöhe von 2 cm, während ca.  60% der  TM in den Fahrgassen verblieben. Der Stickstoffgehalt der Grasmahd stieg im feuchten Jahr 1995 im Laufe der Vegetationsperiode zum Herbst hin an, während er im trockneren Jahr 1996 mit 2,5%  N gering und konstant blieb. Die Grasmahd enthielt insgesamt 2–3%  N in der  TM in der ungedüngten und 2,1–3,9%  N in der  TM in der mineralischen mit NPK bzw. organischen mit jährlich 10 t Stallmist gedüngten Variante bzw. 2,2–2,9%  K in der ungedüngten oder 2,7–4,1%  K in der  TM in der mit Stallmist gedüngten Variante; im Gegensatz dazu verringerte Stallmist die Calciumkonzentration von 0,5–0,7%  Ca in der ungedüngten Parzelle auf 0,3–0,6%  Ca in der  TM der Grasmahd in der organischen Parzelle. Durch Mulchen wurde pro Jahr und  ha Obstanlage 25–50% des Aufwuchses aus den Fahrgassen auf die Baumstreifen (ca. 4.000 m2) verlagert und damit 10–25 kg  N, 2–4 kg  P, 15–25 kg  K, 3–5 kg  Ca und 1–2 kg  Mg; für eine Berechnung der Streudichte pro  ha müssten die ermittelten kg-Werte mit ca.  2,5 (4.000 m2 auf 10.000 m2) multipliziert werden. Der höhere Nährstoffgehalt der Grasmahd wird im Vergleich zu dem Falllaub diskutiert, aus dem die Nährstoffe bereits entzogen wurden. Die in der verlagerten Grasmahd gefundenen Nährelemente deckten bei Stickstoff, Phosphor und Kalium fast die Hälfte und bei Calcium etwa 1/10 der bekannten Entzugswerte für eine Apfelanlage und müssen in umweltfreundlichen, nachhaltigen Düngestrategien für Obstanlagen mit möglichst geschlossenen Nährstoffkreisläufen mit berücksichtigt werden.

A suite of SiOxfilms with oxygen concentrations ranging from x 1 to 1.8 25 at to 3.6 at excess silicon were synthesized by physical vapour deposition. Erbium was incorporated by coevaporation of erbium metal to a concentration of about 0.2 at. A subsequent annealing step was performed at temperatures ranging from 400 °C to 1100 °C to induce phase separation and cluster growth, and to optically activate erbium ions. This range of compositions and annealing temperatures was used to generate a fluorescence map for nanoclustersensitized Er3. Photoluminescence PL spectra were measured in the visible and nearinfrared wavelength regions to explore the nature of the energy transfer between SiNCs and Er3ions. The highest PL intensities for undoped films occurred for samples annealed above 1000 °C, containing silicon nanocrystals. In contrast, in Erdoped films the strongest Er3emission at 1.54 μm was observed from films annealed at temperatures below 1000 °C, demonstrating that amorphous Si nanoclusters support effective energy transfer to the Er3ions. The sensitization was most efficient when the NC peak emission wavelength was near 660 nm 1.88 eV matching the energy of the 4F92band of Er3ions in a silica host. © 2009 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim

Tremor that occurs as a result of a cerebellar lesion, cerebellar tremor, is characteristically an intention tremor. Thalamic activity may be related to cerebellar tremor because transmission of some cerebellar efferent signals occurs via the thalamus and cortex to the periphery. We have now studied thalamic neuronal activity in a cerebellar relay nucleus (ventral intermediate—Vim) and a pallidal relay nucleus (ventralis oral posterior—Vop) during thalamotomy in patients with intention tremor and other clinical signs of cerebellar disease (tremor patients). The activity of single neurons and the simultaneous electromyographic (EMG) activity of the contralateral upper extremity in tremor patients performing a pointing task were analyzed by spectral cross-correlation analysis. EMG spectra during intention tremor often showed peaks of activity in the tremor-frequency range (1.9–5.8 Hz). There were significant differences in thalamic neuronal activity between tremor patients and controls. Neurons in Vim and Vop had significantly lower firing rates in tremor patients than in patients undergoing thalamic surgery for pain (pain controls). Other studies have shown that inputs to Vim from the cerebellum are transmitted through excitatory connections. Therefore the present results suggest that tremor in these tremor patients is associated with deafferentation of the thalamus from cerebellar efferent pathways. The thalamic X EMG cross-correlation functions were studied for cells located in Vim and Vop. Neuronal and EMG activity were as likely to be significantly correlated for cells in Vim as for those in Vop. Cells in Vim were more likely to have a phase lag relative to EMG than were cells in Vop. In monkeys, cells in the cerebellar relay nucleus of the thalamus, corresponding to Vim, are reported to lead movement during active oscillations at the wrist. In view of these monkey studies, the present results suggest that cells in Vim are deafferented and have a phase lag relative to tremor that is not found in normal active oscillations. The difference in phase of thalamic spike X EMG activity between Vim and Vop may contribute to tremor because lesions of pallidum or Vop are reported to relieve cerebellar tremor.

Many lines of evidence implicate the anterior cingulate cortex (ACC, Brodmann’s area [BA] 24) and parasylvian cortex in pain perception. Clinical studies demonstrate alterations in pain and temperature sensation after lesions of these structures. Imaging studies reveal increased blood flow in ACC and parasylvian cortex, both ipsilateral and contralateral to painful stimuli. Additionally, painful stimuli evoke potentials that seem t arise from these cortical structures. Short-duration cutaneous stimulation with a CO2 laser evokes painrelated potentials (LEPs) with a vertex maximum and an initial negative peak followed by a positive wave. The cutaneous laser stimulus evokes a pure pain sensation due to selective activation of cutaneous nociceptors. Electrical source modeling has suggested that the vertex maximum of the scalp LEP arises, in part, from generators in the cingulate gyrus and parasylvian cortex. Thus, imaging and electrophysiologic studies suggest that these cortical structures are activated by painful stimuli. However, these studies incorporate multiple assumptions and therefore do not establish the presence of nociceptive inputs to ACC and parasylvian cortex. We review our recent reports of intracranial potentials evoked by painful stimuli. These studies provide direct evidence of nociceptive inputs to the human ACC and parasylvian cortex

Indirect evidence suggests that the thalamus contributes to abnormal movements occurring in patients with dystonia (dystonia patients). The present study tested the hypothesis that thalamic activity contributes to the dystonic movements that occur in such patients. During these movements, spectral analysis of electromyographic (EMG) signals in flexor and extensor muscles of the wrist and elbow exhibited peak EMG power in the lowest frequency band [0–0.78 Hz (mean: 0.39 Hz) dystonia frequency] for 60–85% of epochs studied during a pointing task. Normal controls showed low-frequency peaks for <16% of epochs during pointing. Among dystonia patients, simultaneous contraction of antagonistic muscles (cocontraction) at dystonia frequency during pointing was observed for muscles acting about the wrist (63% of epochs) and elbow (39%), but cocontraction was not observed among normal controls during pointing. Thalamic neuronal signals were recorded during thalamotomy for treatment of dystonia and were compared with those of control patients without motor abnormality who were undergoing thalamic procedures for treatment of chronic pain. Presumed nuclear boundaries of a human thalamic cerebellar relay nucleus (ventral intermediate, Vim) and a pallidal relay nucleus (ventral oral posterior, Vop) were estimated by aligning the anterior border of the principal sensory nucleus (ventral caudal, Vc) with the region where the majority of cells have cutaneous receptive fields (RFs). The ratio of power at dystonia frequency to average spectral power was >2 (P< 0.001) for cells in presumed Vop often for dystonia patients (81%) but never for control patients. The percentage of such cells in presumed Vim of dystonia patients (32%) was not significantly different from that of controls (31%). Many cells in presumed Vop exhibited dystonia frequency activity that was correlated with and phase-advanced on EMG activity during dystonia, suggesting that this activity was related to dystonia. Thalamic somatic sensory activity also differed between dystonia patients and controls. The percentage of cells responding to passive joint movement or to manipulation of subcutaneous structures (deep sensory cells) in presumed Vim was significantly greater in patients with dystonia than in control patients undergoing surgery for treatment of pain or tremor. Dystonia patients had a significantly higher proportion of deep sensory cells responding to movement of more than one joint (26%, 13/52) than did “control” patients (8%, 4/49). Deep sensory cells in patients with dystonia were located in thalamic maps that demonstrated increased representations of parts of the body affected by dystonia. Thus dystonia patients showed increased receptive fields and an increased thalamic representation of dystonic body parts. The motor activity of an individual sensory cell was related to the sensory activity of that cell by identification of the muscle apparently involved in the cell's receptive field. Specifically, we defined the effector muscle as the muscle that, by contraction, produced the joint movement associated with a thalamic neuronal sensory discharge, when the examiner passively moved the joint. Spike X EMG correlation functions during dystonia indicated that thalamic cellular activity less often was related to EMG in effector muscles (52%) than in other muscles (86%). Thus there is a mismatch between the effector muscle for a thalamic cell and the muscles with EMG correlated with activity of that cell during dystonia. This mismatch may result from the reorganization of sensory maps and may contribute to the simultaneous activation of multiple muscles observed in dystonia. Microstimulation in presumed Vim in dystonia patients produced simultaneous contraction of multiple forearm muscles, similar to the simultaneous muscle contractions observed in dystonia. These observations are consistent with a model in which sensory input to Vim in dystonia is transmitted through altered sensory maps to activate multiple muscles in the periphery, producing the overflow of muscle activation that is characteristic of dystonia.

Representation of cardiovascular function has not been investigated in the human thalamus. In the rat, the insular cortex is the principal forebrain site of cardiovascular representation whose afferents originate from a circumscribed thalamic area (nucleus ventralis posterolateralis-parvicellular portion, VPLpc). We therefore evaluated 4481 thalamic cells for phasic cardiovascular activity using extracellular recording techniques in 60 unanesthetized patients undergoing neurosurgical procedures. We identified 26 cells with phasic activity strongly related to the cardiac cycle in 10 patients. These cells clustered within the ventrocaudal nucleus of the thalamus (the principal sensory nucleus analagous to the ventral posterior thalamic group in the rat and monkey) and were equally distributed between the right and left sides. The majority of these cells (17/26) showed peaks of phasic neuronal activity within 50 ms of the peak systolic pressure; 35% had peripheral cutaneous fields in areas to which cardiac pain is often referred. We suggest that these cells may be involved in the integration of afferent baroreceptor information; may possibly be concerned with the generation and/or processing of central cardiac pain in humans; and that their derangement may possibly contribute to the lethal cardiovascular disturbances which occur in fatal familial insomnia.

1. We have studied the sensations evoked by threshold microstimulation (TMS) in the area of the human principal sensory nucleus of the thalamus [ventralis caudalis (Vc)] in patients (n = 11) undergoing stereotactic surgery for the treatment of movement disorders and pain. Preoperatively, patients were trained to describe somatic sensory stimuli using a standard list of descriptors. This same list was used to describe sensations evoked intraoperatively by thalamic microstimulation. Stimulation sites (n = 216) were defined by location within the area where the majority of cells had a reproducible response to innocuous cutaneous stimulation (core region) or in the cellular area posterior and inferior to the core region (posteroinferior region). 2. TMS-evoked sensations were categorized as paresthetic if the descriptors "tingle," "vibration," or "electric current" were chosen by the patient to describe the sensation and as thermal/pain if the descriptors "cool," "warm," "warm and cool," or "pain" were chosen. Thermal/pain sensations were evoked by stimulation in 82% (9/11) of patients and at 19% of sites studied. These results suggest that thalamic microstimulation can evoke thermal/pain sensations reproducibly across patients. 3. Thermal/pain sensations were evoked more frequently by stimulation at sites in the posteroinferior region (30%) than by stimulation at sites in the core region (5%). Nonpainful thermal sensations composed the majority of thermal/pain sensations evoked by stimulation in both the core (80%) and posteroinferior regions (86%). Sites where stimulation evoked pain and nonpainful cool sensations were found anterior to the area where nonpainful warm sensations were evoked. Thermal/pain sensations were evoked at sites located medially near the border between the core and posteroinferior regions. 4. Radiologic techniques were used to determine the presumed nuclear location of stimulation sites. Thermal/pain sensations were evoked less frequently by stimulation in the part of Vc included in the core region than by stimulation in any of the following: the part of Vc included in the posteroinferior region, ventralis caudalis portae nucleus, ventralis caudalis parvocellularis nucleus, or the white matter underlying the ventral nuclear group. 5. The location of the sensation evoked by stimulation [projected field (PF)] varied widely in size. PFs were categorized as large if they involved more than one part of the body (e.g., face and arm) or if they crossed at least one joint proximal to the metacarpophalangeal joint or to the metatarsophalangeal joint. PFs were more frequently large at sites where thermal/pain sensations were evoked by TMS (33%) than at those where paresthesia were evoked (6%).(ABSTRACT TRUNCATED AT 400 WORDS)

This report describes K+efflux, K+and Ca2+uptake responses to endothelins (ET-1 and ET-3) in cultured endothelium derived from capillaries of human brain (HBEC). ET-1 dose dependently increased K+efflux, K+and Ca2+uptake in these cells. ET-1 stimulated K+efflux occurred prior to that of K+uptake. ET-3 was ineffective. The main contributor to the ET-1 induced K+uptake was ouabain but not bumetanide-sensitive (Na+-K+-ATPase and Na+-K+-Cl−cotransport activity, respectively). All tested paradigms of ET-1 effects in HBEC were inhibited by selective antagonist of ETAbut not ETBreceptors and inhibitors of phospholipase C and receptor-operated Ca2+channels. Activation of protein kinase C (PKC) decreased whereas inhibition of PKC increased the ET-1 stimulated K+efflux, K+and Ca2+uptake in HBEC. The results indicate that ET-1 affects the HBEC ionic transport systems through activation of ETAreceptors linked to PLC and modulated by intracellular Ca2+mobilization and PKC.

Within the canonical Weyl gauge formulation, the axial gauge representation of QCD on a torus is derived. The resolution of the Gauss law constraint is achieved by applying unitary gauge fixing transformations. The result of this formal development is a Hamiltonian explicitly formulated in terms of unconstrained degrees of freedom. Novel features of this Hamiltonian are the non-perturbative dynamics of two-dimensional degrees of freedom appearing in the gauge-fixing procedure, such as Jacobian and centrifugal barrier. These two-dimensional fields appear to be essential for the infrared properties of the theory. The global residual gauge symmetries of QCD are established in this representation. It is shown that SU(N) gauge theories may exhibit at most N-1 massless vector (gauge) bosons. The implications for the phase structure of non-abelian gauge theories (QCD, Georgi-Glashow model) are discussed.Copyright 1994, 1999 Academic Press, Inc.

THE spatiotemporal progression of cortical spreading depression was investigated by imaging of activity-dependent intrinsic optical signals in rat sensorimotor cortex. In contrast to the traditional conception of a uniformly propagating event, the evolution of the spreading depression was characterized by an asymmetrical propagating wavefront and a non-uniform dispersion of optical signals behind the wavefront. As these optical signals are a reflection of underlying molecular and metabolic processes, the imaging approach to spreading depression might constitute a useful technique for investigating the functional organization as well the pathophysiology of the cerebral cortex.

F. A. Lenz, M. Rios, A. Zirh, D. Chau, G. Krauss, and R. P.Lesser.Painful stimuli evoke potentials recorded over the human anterior cingulate gyrus. J. Neurophysiol.79: 2231–2234, 1998. Clinical studies of cingulotomy patients and imaging studies predict that the human cingulate gyrus might display pain-related activity. We now report potentials evoked by painful cutaneous stimulation with a CO2laser (LEP) and recorded from subdural electrodes over the medial wall of the hemisphere. In response to facial laser stimulation on both sides, a negative (latency 211–242 ms) and then a positive wave (325–352 ms) were recorded from the cortex of right medial wall and from the falcine dura overlying the left medial wall. Medial wall LEPs were similar to scalp LEPs and were largest over the anterior cingulate and superior frontal gyri just anterior to motor cortex contralateral to the side of stimulation. These results demonstrate that there is significant direct nociceptive input to the human anterior cingulate gyrus (Brodmann's area 24).

Lenz, F. A. and P. M. Dougherty.Neurons in the human thalamic somatosensory nucleus (ventralis caudalis) respond to innocuous cool and mechanical stimuli. J. Neurophysiol.79: 2227–2230, 1998. A population of neurons in the principal somatosensory nucleus of human thalamus (ventralis caudalis, Vc) had a significant tonic, graded response to cool stimuli and also responded to innocuous mechanical stimuli (mechanical-cool neurons). These neurons were clustered at the dorsal aspect of medial Vc. Stimulation at the sites where these neurons were recorded evoked tingling sensations in the part of the body including or adjacent to the receptive field of these neurons. These neurons may contribute to the mechanism that mediates the perception of cold in man.

Abstract Animal studies suggest that an olivocerebello-bulbospinal pathway mediates harmaline induced tremor, which resembles essential tremor in humans. However, recent evidence suggests that thalamocortical pathways participate in essential tremor. Thalamic single neuron activity has been analysed during thalamotomy for essential tremor. It has been shown by spectral cross correlation analysis that thalamic activity has a significant, linear relation to forearm EMG activity during tremor. The presence of this tremor related activity at the site where a lesion abolishes essential tremor suggests that the thalamus has an important role in the mechanism of essential tremor.

1. We have studied the functional and somatotopic properties of 531 single mechanoreceptive thalamic neurons in humans undergoing stereotactic surgery for the control of movement disorders and pain. The majority of these somatosensory cells had small receptive fields (RFs) and were activated in a reproducible manner by mechanical stimuli applied to the skin or deep tissues. These neurons, which we termed "lemniscal," could be further classified into those responding to stimulation of cutaneous (76% of lemniscal sensory cells) or deep (24%) structures. 2. The incidence of neurons having cutaneous or mucosal RFs in the perioral region, thumb, and fingers (66%) was much higher than that of neurons having RFs elsewhere on the body. Most of the deep cells were activated by movements of and/or mechanical stimuli delivered to muscles or tendons controlling the elbow, wrist, and fingers. 3. Sequences of cells spanning several millimeters in the parasagittal plane often exhibited overlapping RFs. However, RFs changed markedly for cells separated by the same distances in the mediolateral direction. This suggests that the cutaneous somatotopic representation of each region of the body is organized into relatively thin sheets of cells oriented in the parasagittal plane. 4. By comparing neuronal RFs in different parasagittal planes in thalamus of individual patients we have identified a mediolateral representation of body surface following the sequence from: intraoral structures, face, thumb through fifth finger to palm, with forearm and leg laterally. 5. Along many trajectories in the parasagittal plane the sequence of cells with overlapping RFs was interrupted by another sequence of cells with RFs corresponding to a different body region. The RFs of the intervening sequence characteristically represented body regions known to be located more medially in thalamus (see 3 above). These findings could be explained if the lamellae postulated above were laterally convex. 6. Cells responding to deep stimulation (deep cells) could be further classified into those responding to joint movement (63%), deep pressure (15%), or both (22%). Deep cells were found usually at the anterior-dorsal border and sometimes at the posterior border of the region containing cells responding to cutaneous stimuli. Although there was some overlap in the RFs, deep cells representing wrist were found medial to those representing elbow, and both of these were found medial to cells representing leg.(ABSTRACT TRUNCATED AT 400 WORDS)

A patient with unremitting, medically intractable hemiballismus underwent a pallidotomy that abolished his involuntary movements. Firing rates of cells in the internal segment of the globus pallidus (GPi) recorded during this procedure were significantly lower than those observed during pallidotomy for Parkinson's disease, either “on” or “off” medication. Firing patterns in hemiballismus were characterized by low‐frequency modulation of the firing rate. These results are consistent with the hyperkinetic model, which suggests that hemiballismus results from decreased inhibition of the pallidal relay nucleus of the thalamus by the GPi. The efficacy of surgery in the case of hemiballismus demonstrates that pallidotomy can be an effective treatment for this condition and suggests that patterned neuronal activity in the GPi is important in the mechanism of hyperkinetic disorders.

A reversed-phase high-performance liquid chromatographic method is described for the qualitative and quantitative determination of carotenoid pigments in citrus fruits. By using gradient elution, a fast and efficient separation of complex carotenoid mixtures was achieved in a one-step procedure. Retention times and peak areas were of good reproducibility. The method may also be applied to other plant carotenoid extracts.

The global residual gauge symmetry of electrodynamics, the displacement symmetry, is discussed within the Weyl-gauge formulation and used to characterize different phases of the Maxwell field coupled to matter. Unlike other global symmetries, the displacement symmetry, in the absence of interactions or in the weak coupling regime, is realized in the Nambu-Goldstone mode. The displacement symmetry will be shown to be realized in the Wigner-Weyl mode in the plasma and superconducting states; this discussion develops a novel perspective of the plasma oscillations. Other examples are the states of the Schwinger model and the non-perturbative phase of the Abelian Higgs model. The Higgs mechanism is interpreted as formation of a phase with a high degree of symmetry. Finite photon mass and shielding of external fields will be recognized as the characteristic properties of these symmetric phases.

A comparative dynamical study of axial gauge QED and QCD is presented. Elementary excitations associated with particular field configurations are investigated. Gluonic excitations analogous to linearly polarized photons are shown to acquire infinite energy. Suppression of this class of excitations in QCD results from quantization of the chrome-electric flux and is interpreted as a dual Meissner effect, i.e., as expulsion from the QCD vacuum of chromo-electric fields which are constant over significant distances. This interpretation is supported by a comparative evaluation of the interaction energy of static charges in the axial gauge representation of QED and QCD.

An analysis method to detect the presence of feedback between biological signals, particularly those associated with the central nervous system, is presented. The technique is based on recent results in the system identification literature involving the concept of a feedback free process. It may be applied to volume conducted signals such as EEG and EMG, as well as to neuronal spike trains through the use of a data transformation procedure. The utility of the technique is then demonstrated in a study of the relationship between Parkinsonian tremor and certain tremor cells found in the thalamus of Parkinsonian patients, using data collected during thalamotomies. The results obtained suggest that feedback mechanisms may be an important factor contributing to Parkinsonian tremor.

In the framework of the canonical Weyl gauge formulation of QED, the quantum mechanics of gauge fixing is discussed. Redundant quantum mechanical variables are eliminated by means of unitary transformations and Gauss′s law. This results in representations of the Weyl-gauge Hamiltonian which contain only unconstrained variables. As a remnant of the original local gauge invariance global residual symmetries may persist. In order to identify these and to handle infrared problems and related "Gribov ambiguities," it is essential to compactify the configuration space. Coulomb, axial, and light-cone representation of QED are derived. The naive light-cone approach is put into perspective. Finally, the Abelian Higgs model is studied; the unitary gauge representation of this model is derived and implications concerning the symmetry of the Higgs phase are discussed.

1. We explored the region of the principal sensory nucleus of thalamus (Vc) during stereotactic surgical procedures for treatment of patients with pain after spinal cord transection (n = 23). Receptive fields (RFs) of thalamic single neurons and locations of sensations evoked by stimulation (projected field, PF) were determined by standard methods. The cellular thalamic region where sensations were evoked at < 25 microA was termed the "region of Vc." The region of Vc in spinal patients was subdivided into different areas according to RF and PF locations. Areas that were distant from the representation of the anesthetic part of the body were termed "spinal control" areas, whereas those that were adjacent to or included in the representation of the area of absolute sensory loss were termed "border zone/anesthetic" areas. The region of Vc in movement disorder patients were termed the "control" area. 2. Border zone/anesthetic areas of thalamus often exhibited increased representations of the border of the anesthetic part of the body in comparison with the representation of the same parts of the body in control and spinal control areas. 3. In control and spinal control areas the locations of RFs and PFs were usually well matched. However, in border zone/anesthetic areas of the thalamus there was frequently a mismatch between the location of RFs and PFs (RF/PF mismatch). In border zone/anesthetic areas, RFs were often located on the border of the anesthetic part of the body whereas PFs were referred to anesthetic parts of the body. 4. Analysis of first- and higher-order properties of spontaneous neuronal activity revealed that spike trains could be classified into two groups with distinct patterns of activity. The R group (n = 49) was characterized by independence of sequential interspike intervals (ISIs), a Poisson distribution of ISIs, initially inhibitory or flat autocovariance function (acvf), and low level of high-frequency bursting. The O group (n = 26) was characterized by correlation of sequential ISIs, large sustained postspike facilitation on the acvf, and high prevalence of high-frequency bursting--all consistent with a bursting pattern of activity. A third group of spike trains (n = 17) had an initially inhibitory or flat acvf and a unimodal, positively shifted, ISI distribution that did not meet criteria for a Poisson distribution. 5. Spike trains in the R group were much more common in control and control spinal areas, whereas those in the O group were more common in border zone/anesthetic areas.(ABSTRACT TRUNCATED AT 400 WORDS)

Two methods (whole-plant growth analysis and gas exchange) were used to measure the response of Psophocarpus tetragonolobus (L.) DC cultivar ‘UPS 99’ to the environment. This plant had an optimal temperature for root growth of 25°C, its rate of acetylene reduction (when inoculated with Rhizobium, strain ‘RRIM 56’) was maximal at 30°C and it required an atmospheric temperature of about 35°C for optimal shoot growth. Maximum water-use efficiency was ca. 33 mg CO2·g H2O-1. The rate of photosynthesis reached a plateau at 900 vpm CO2-this condition also gave the lowest rate of transpiration. Under normal conditions, the light compensation point was at 1.7 klx, while that for CO2 was 60 vpm. Photorespiration diminished gross photosynthesis of P. tetragonolobus by forty percent. Water stress (as measured by sensitivity to slightly increased CO2 levels) caused rapid closure of stomata, and the response was ‘remembered’ for up to five days.

The specific rate of CO(2) efflux (respiration) from roots of intact fruiting calamodin plants (Citrus madurensis Lour.) showed no diel trend, and did not respond significantly to short-term (2 day) changes in shoot irradiance. Mean root respiration rate was about 8.4 nmol CO(2) g(-1) s(-1) at 20 degrees C, and increased with temperature with a Q(10) of about 2. In calamodin plants, the proportion of total root length that was white averaged 6.0 mm m(-1). Respiration of roots of apple plants (Malus domestica Borkh.), planted in spring as rootstocks and grown at high irradiance and N supply, declined from about 5.3 to 2.8 nmol CO(2) g(-1) s(-1) between 46 and 138 days after bud burst. At 50% irradiance, root respiration was reduced more than 25% at 46 and 92 days after bud burst, but was not significantly affected later in the season. Reducing shoot irradiance reduced the proportion of total root length that was white, e.g., from 217 to 146 mm m(-1) at 46 days after bud burst. For plants previously grown at low irradiance, increasing shoot irradiance for 6 days increased the rate of root respiration by 5 to 10%. For plants previously grown at high irradiance, reducing shoot irradiance for 6 days reduced root respiration by about 20% early in the season, but had no significant effect later in the season. For plants grown with low-N supply (5% of the high-N), root respiration was reduced early in the season, but was not significantly affected later. Reducing the N supply increased slightly the proportion of total root length that was white. For plants previously grown with low-N, increasing the N supply for 6 days reduced further the rate of root respiration. For plants previously grown with high-N, reducing the N supply for 6 days did not significantly affect the rate of root respiration. Specific respiration rates of root systems excised from mature trees growing outdoors peaked in June, at about 2.4 nmol CO(2) g(-1) s(-1), and then declined for the remainder of the growing season.

Lenz, F. A., R. H. Gracely, T. A. Zirh, D. A. Leopold, L. H. Rowland, and P. M. Dougherty.Human thalamic nucleus mediating taste and multiple other sensations related to ingestive behavior. J. Neurophysiol.77: 3406–3409, 1997. Until now, taste was the only primary sensory modality for which the human central nervous system pathways were unknown. We report sensations evoked by stimulation at microampere current levels in the region of the human thalamic nucleus (ventralis caudalis parvocellularis internis) corresponding to the monkey taste relay nucleus. Stimulation in this region during awake neurosurgical procedures evoked special visceral/somatic (taste/pungent smell), general visceral (fullness of a hollow viscus), as well as painful and nonpainful general somatic sensations. General somatic or visceral sensation was evoked by stimulation at 80% of sites where special visceral/somatic sensation was evoked. These results suggest that primate taste relay mediates multiple sensations in addition to taste.

Dougherty, P. M., Y. J. Li, F. A. Lenz, L. Rowland, and S. Mittman.Correlation of effects of general anesthetics on somatosensory neurons in the primate thalamus and cortical EEG power. J. Neurophysiol.77: 1375–1392, 1997. The effects of two types of general anesthetic on the neurophysiological properties of the primate somatosensory thalamus were correlated with effects on frontal cortex electroencephalographic (EEG) power and spectral properties. Graded doses of the intravenous agent methohexital sodium (METH) were studied in 12 cells in three monkeys on a halothane baseline anesthetic. Low doses of METH (0.2–1.0 mg/kg) produced a reduction of EEG power but had no effects on spontaneous or evoked thalamic activity. EEG power showed maximal attenuation after 2.0 mg/kg METH, whereas decreases in thalamic activity were first noted over a similar moderate dose range (2.0–5.0 mg/kg). The physiological parameter most sensitive to METH was the spontaneous activity, which showed initial changes in rate and pattern at moderate doses followed by marked inhibition at higher doses. Finally, the high dose of METH (10.0 mg/kg) produced marked reduction in all neurophysiological parameters with recovery over the following 30–45 min. The effects of the volatile anesthetic halothane were studied on 15 cells in four monkeys anesthetized with pentobarbital sodium. The low dose of halothane (0.25%) produced a facilitation of responses to cutaneous stimuli as well as a decrease in the rate and burst patterns in the spontaneous activity. The power in the EEG was not affected at this concentration. The responses of the cells to the mechanical stimuli at moderate doses (0.5–1.0%) of halothane returned to the baseline magnitude, whereas spontaneous activity remained unaffected compared with initial effects. EEG power was reduced by 1% halothane. Finally, all neurophysiological parameters showed profound reduction at the highest halothane concentrations (2.0–3.0%) with recovery over the next 30–45 min. In conclusion, the two classes of anesthetics most commonly used for acute neurophysiological studies in the primate show well-defined thresholds at which changes in the response properties of thalamic neurons are produced. This threshold for the barbiturates and halothane can be predicted by monitoring of cortical EEG.

Lenz, F. A., M. Rios, D. Chau, G. L. Krauss, T. A. Zirh, and R. P. Lesser.Painful stimuli evoke potentials recorded from the parasylvian cortex in humans. J. Neurophysiol.80: 2077–2088, 1998. Cutaneous stimulation of the face and hand with a CO2laser in three awake patients evoked potentials (LEPs) recorded from the dominant left parasylvian cortex. These were recorded by means of a subdural grid of electrodes implanted for evaluation of epilepsy. Stimulation of the contralateral face resulted in waveforms consisting of a negative potential (N2, 162 ± 5 ms; mean ± SE) followed by a positive potential (P2, 340 ± 18 ms). Both waves occurred at longer latency after hand than after facial stimulation. N2 and P2 potentials recorded from the grid correspond well in morphology to those recorded from the scalp in four additional patients tested with the same stimulation paradigm. The N2 waves recorded from the subdural grid occurred at significantly shorter latencies than did those recorded from the scalp (184 ± 6 ms), but the P2 waves at the grid occurred at significantly longer latencies than did those recorded at the scalp (281 ± 13 ms). The amplitudes of the potentials recorded from the grid were maximal over the parietal operculum both for contralateral stimulation of the face or hand and for ipsilateral stimulation of the face. Potentials also were recorded in this area after stimulation of the ipsilateral hand. The cortical distributions of these potentials suggest that their generators are located in the parietal operculum or in the insula, or in both, consistent with previous PET, magnetoencephalographic, and scalp LEP source analyses. These previous analyses provide indirect evidence of nociceptive input to parasylvian cortex because the interpretation of each analysis incorporates multiple assumptions. The present results are the first direct evidence of nociceptive input to the human parasylvian cortex.

Bei einem Gewittersturrn am 1.8. 1983 fanden im Gebiet des Nationalparks Bayerischer Wald zahlreiche relativ großflächige Windwürfe start, wobei besonders die Fichten-Auw~lder betroffen waren, hmerhalb der Reservatszone finder seitdem eine vom Menschen unbeeinflußte Besrandesentwicklung start; aut~erhalb dieser Gebiete wurden die Windwurfflächen zwar geräumt, jedoch nicht wieder künstlich bestockt. 1988 wurde eine Methode zur lan~ristigen Dokumentation der Bestandesentwicklung entworfen und die erste Bestandeserhebung durchgeführt. Dabei tassen sich 5 Jahre nach dem Smrmereignis folgende Feststeltuneen treffen:1.Auf der belassenen Windwurffläche wird die Bodenvegetation nach wie vor von den typischen Waldbodenpflanzen des Fi~htenwaldes beherrscht, und zwar sowohl der Artenzahl als auch der Artmächtigkeit nach. Dageoen treten auf der geräumten Windwurffläche insbesondere die Schlagflurarten nach Artenzahl und Artmäichtigkeit so stark hervor, daß yon einer Schlagflurgesellschaft (hier: Rubetum idaei) zu sprechen ist.2.Auf der belassenen Windwurffläche treten Bestände mit dem soziologischen Charakter einer Schlagflur nur punktuell, und zwar im Bereich der dutch Heraushebeln der Wurzeheller entstandenen Mulden auf.3.Der Gehölzjungwuchs setzt sich auf der belassenen Windwurfflläche aus Fichte und Birke zusammen, wobei sich die Fichten-Population überwiegend aus bereits vor dem Windwurfereignis vorhandenen, unterständigen Individuen rekrutiert, die Birken-Population aber erst nach dem Ereignis eingeflogen ist. Auf der geräumten Fläche ist die Birke zwar ebenfalls stark vertreten, die Fiehte aber deutlich schwächer; möglicherweise wurde die Fichten-Ausgangspopulation durch die Räumungsarbeiten weitgehend vernichtet.4.Die sich neu entwickelnde Baumschicht läßt auf den belassenen WindwuKflächen bereits im 5. jahr nach Bestandesstörung den Aufbau eines Fichten-Bestandes erkennen, der- je nach Verteilungsmuster der unterständigen Pflanzen - eine kleinräumig wechselnde Dichte annehmen wird. Dagegen geht die Entwicklung auf der geräumten Fläche stärker in die Richtung eines Birken-Vorwaldes.5.Damit laufen auf belassener und geräumten Windwurffläche bei der Rückkehr zu einem standortsgemäßen Waldbestand prinzipieli-unterschiedliche Entwicklungsprozesse ab: auf der geräumten Fläche Abfolge verschiedener Pflanzengesellschaften (Sukzession), auf der belassenen Fläche Restitution einer Baumschicht bei wenig veräderter Krautschicht.6.Grund für die unterschiedliche Entwickhmg ist der unterschiedliche Grad der mechanischen Bodenstörung: auf der geräumten Fläche fast/überall, auf der belassenen Fläche nur im Bereich der herausgehebelten Wurzelteller. An den offenen Bodensteilen findet zum einen eine Rekrutierung aus der Samenbank start, zum anderen werden für anemochore Arten geeignete Etablierungsplärze geboten. On the 1stof August, 1983, a thunderstorm crossed the area of the "Nationalpark Bayerischer Wald", demolishing a large number of forest stands, especially the near-natural spruce forests of the wet valleys (Calamagrostio villosae-Piceetum) by windfall. Since then inside the reservation zone of the national park the development of the blown-over forests takes place without any direct influence of man. Outside the reservation zone the windfall areas were cleared, but not reforested. In 1988, a set of permanent sample plots was installed, and a first documentation of the vegetation on both cleared and uncleared areas took place. The following results can be reported five years after the storm:1.Ground vegetation of the uncleared windfall areas normally differs little from that of the previous Calamagrostio-Plceetum, regarding both quality, and quantity of species composition.2.In contrast, vegetation of the cleared windfall areas represents the vegetation which develops after logging ("Schlagflur"), here the plant community "Rubetum idaei". This vegetation type is represented on the uncleared areas only in small patches: the throughs created by the uprooted trees.3.Uncleared windfall areas are covered by large numbers of young spruce (Picea abies) and some of birch (Betula ssp.). Most of the sptxice trees were already present in the understory of the previous forest when the windfall happened. On the cleared areas young spruce trees occur only in small numbers. The reason may be destruction of the spruce regeneration during the clearing procedure. Birch, on the other hand, is common especially on the cleared windfall areas.4.Five years after the windfall, the developing tree cover on the uncleared areas already shows the renewal of a spruce stand which will, depending on the density of previous understory trees, be very variable in density. In contrast, a pioneer forest is developing on the cleared areas.5.Therefore, vegetation development of cleared and uncleared windfall areas follows different traits: succession, a replacement of different plant communities on tile cleared areas, but restitution of the previous tree cover and little change of the ground vegetation on uncleared areas.6.During logging procedures, disturbance of ground vegetation as well as of soils takes place nearly everywhere: the soil seed bank becomes active, and species possessing flying diaspores may invade, both initiating the succession. This is not true for blown-over forest stands which are not influenced by man (with the exception of small patches where the trees were uprooted).

A study of the center symmetric phase of SU(2) Yang–Mills theory is presented. Realization of the center symmetry is shown to result from non-perturbative gauge fixing. Dictated by the center symmetry, this phase exhibits already at the perturbative level confinement-like properties. The analysis is performed by investigating the dynamics of the Polyakov loops. The ultralocality of these degrees of freedom implies significant changes in the vacuum structure of the theory. General properties of the confined phase and of the transition to the deconfined phase are discussed. Perturbation theory built upon the vacuum of ultralocal Polyakov loops is presented and used to calculate, via the Polyakov loop correlator, the static quark– antiquark potential.

A new type of zone plate is proposed whose purpose is to increase the contrast in electron micrographs. It consists of a circular aperture and a number of concentric rings, and it is arranged in the back focal plane of an electron objective lens with spherical aberration. The diameters of the outer rings are chosen such as to leave through only such parts of the wave surface which reach the image point with a phase delay of (2n+1)p relative to its paraxial part. The intensity distribution in the image plane is calculated for this zone plate and for a similar type of zone plate suggested byHoppe whose purpose is to reduce the resolution limit. Numerical calculations are made for the special case that the intensity is constant over the plane of the zone plate. The results show that an increase of resolving power may be expected if Hoppe's plate is used, and that the image contrast may be considerably increased by the new contrast plate without any serious reduction of resolving power.