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PubMed2006

Photocount distribution of photons emitted from three sites of a human body.

Spontaneous photon emission from 30 sites on the skin of a live human subject is measured at different times and on different days. Signals from three representative sites of low, intermediate and high intensities are selected for further analysis. Fluctuations in these signals are measured by the probabilities of detecting different numbers of photons in a bin. The probabilities have non-classical features and are well described by the signal in a quantum squeezed state of photons. Measurements with bins of three sizes yield same values of three parameters of the squeezed state. A procedure for making correction due to background noise is developed. The correction changes the parameters of the quantum state. The new state appears more like a coherent state of photons.

Biophysical Phenomena↗
PubMed2004

Potential of [11C]TMSX for the evaluation of adenosine A2A receptors in the skeletal muscle by positron emission tomography.

We examined the potential of [7-methyl-11C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([11C]TMSX) for the assessment of adenosine A2A receptors in muscle. In rodents, specific binding of [11C]TMSX was observed in muscle and heart by blockade with A2A-selective CSC and non-selective theophylline, but not with A1-selective DPCPX. Swimming exercise fluctuated radioligand-receptor binding in these tissues. In a PET study of two subjects, theophylline-infusion slightly deceased the distribution volume of [11C]TMSX in the heart (20% reduction) and muscle (10% reduction), which suggested the specific binding.

Adult↗
PubMed1996

Voltage-gated ionic channels in cultured rabbit articular chondrocytes.

The membrane properties of cultured cells of rabbit articular chondrocytes were studied using the whole-cell patch clamp technique. The average cell capacitance was 37.9 +/- 9.0 pF (n = 13), and the cell resting potential was -41.0 +/- 7.0 mV (n = 11). We were unable to induce an action potential by applying a depolarizing current. Upon step depolarization, under voltage clamp conditions, one kind of inward and two kinds of outward currents were elicited. The inward current was initially observed at around -30 mV, peaked at 0 mV, and reversed at around +90 mV. Tetrodotoxin (TTX; 1 microM) was shown to completely block this inward current. At steady state, the inward current was half-inactivated at -51 mV, with a slope factor of 6.3 mV. Two outward currents were determined from measurements of activation threshold, reversal potential, and pharmacological responses. One was observed at around -30 mV, and its amplitude increased with membrane depolarization. Extracellularly applied 4-aminopyridine (4 AP) (1 mM) and tetraethyl ammonium chloride (TEA) (5 mM) blocked this current. The other outward current was observed at around +10 mV, and its direction reversed at a potential close to that predicted by the Nernst equation for a Cl- selective channel. This current fluctuated markedly, and the fluctuation did not decline throughout the 100 ms of the step pulse. Extracellularly applied 4-acetamido-4'-isothiocyanostilbenezene-2,2-disulfonic acid (SITS) (0.25 mM) blocked this current, but the same dose of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) had little effect. These results suggest the presence of TTX-sensitive Na+, 4-AP- and TEA-sensitive K+, and SITS-sensitive Cl- channels in rabbit articular chondrocyte membrane. The functional significance of these channels is discussed.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2003

Estimation of methane emission from rice cultivation in Korea.

This study focused on estimating a methane (CH4) inventory and developing mitigation options in South Korea, and was performed jointly in an integrated national research program on CH4 from rice fields conducted by three National Agricultural Research Institutes, under the Rural Development Administration during 1993-1997. Methane emissions were measured by a closed chamber method, in rice plots at three locations (Suwon, Iksan, and Milyang) with the single rice cropping system. All experimental data from 5 years of study were summarized and used for calculating nation-wide CH4 emissions. Temperature, soil type, cultural practices, water management, organic matter management, and cultivar selection significantly affected the fluctuations of CH4 emissions. The two most promising mitigation options for reducing emissions were altered water management, in particular mid-season aeration by short-term drainage, and improved organic matter management, by promotion of aerobic degradation through composing or soil incorporation. Annual total CH4 emission in Korea changed from 410Gg in 1990 to 339Gg in 2000, due mainly to a decrease in the cultivated area of paddy rice. If we convert annual CH4 emission to Global Warming Potential as CO2 equivalent, it amounts to 7.1 M CO2 t yr(-1) of greenhouse gas emitted to the atmosphere in 2000 from the rice fields in Korea, which is just 5.3% of the annual CO2 emission from the industry and energy sector. More importantly, the balance between CO2 uptake by photosynthesis and CO2 emission is positive (a net sink), so that rice culture actually has net benefits for the global atmospheric carbon issue. Further reductions in emission amounts, by following recommendations in this article, could make these benefits even greater.

Agriculture↗
PubMed1993

Substitution processes in molecular evolution. I. Uniform and clustered substitutions in a haploid model.

A computer simulation of the process of nucleotide substitutions in a finite haploid population subject to selection in a randomly fluctuating environment provides a number of unexpected results. For rapidly fluctuating environments, substitutions are more regular than random. A small mutation-rate approximation is used to explain the regularity. The explanation does not depend heavily on the particulars of the haploid model, leading to the conjecture that many symmetrical models of molecular evolution with rapidly changing parameters may exhibit substitutions that are more regular than random. When fitnesses change very slowly, the simulation shows that substitutions are more clumped than random. Here a small-mutation approximation shows that the clustering is due to the increase in fitness that accompanies each successive substitution with a consequent lowering of the effective mutation rate. The two observations taken together suggest that the common observation that amino acid substitutions are clustered in time is due to the presence of parameters that change very slowly.

Biological Evolution↗
PubMedDate not supplied

Clinical and pathologic features of two groups of patients with dementia with Lewy bodies: effect of coexisting Alzheimer-type lesion load.

The objectives of this study were to examine the clinical and pathologic features of two subgroups of patients with dementia with Lewy bodies (DLB) differing in Alzheimer disease (AD)-type pathology load and to identify clinical variables useful in the differential diagnosis from AD. The records of 64 consecutive demented patients were reviewed. Pathologic diagnoses were independently established [35 AD cases, 11 cases of pure dementia with Lewy bodies (pDLB), and 18 cases of combined AD plus Lewy bodies (AD+LB)], and several neurodegenerative lesions were quantified. Clinical and pathologic data were compared between groups with univariate and multivariate analyses. Compared with the other groups, pDLB cases had more frequent acute-subacute onset of dementia [45% vs. AD (3%) and AD+LB (16%)], early parkinsonism [45% vs. AD (0%) and AD+LB (0%)], early [27% vs. AD (0%) and AD+LB (0%)] and late [73% vs. AD (11%) and AD+LB (16%)] hallucinations, fluctuating course [46% vs. AD (9%) and AD+LB (22%)], delusions [45% vs. AD (11%) and AD+LB (6%)], spontaneous parkinsonism [63% vs. AD (8%) and AD+LB (16%)], less frequent ideomotor apraxia and loss of insight, earlier urinary incontinence [3.2 +/- 1.4 years after onset vs. AD (6.3 years) and AD+LB (5.8 years)], shorter duration of dementia [7.7 +/- 2.4 years vs. AD (9.6 years) and AD+LB (11 years)], milder atrophy in computed tomography scans, greater brain weight, more transcortical spongiosis, wider cortex and subcortex, and less amyloid angiopathy. All pDLB cases but no AD cases had abnormal CA2 neurites. The clinical features of AD+LB patients were similar to those of AD patients other than more frequent acute-subacute onset and fluctuating evolution. Discriminant analyses selected four clinical variables differentiating pDLB from the other two groups as a whole: acute-subacute onset, early parkinsonism, early hallucinations, and early onset of urinary incontinence. Two or more of these features identified pDLB with a sensitivity of 81.8% and a specificity of 95.9%. Differentiation between the three groups (pDLB, AD+LB, and AD) or between both groups with LB (DLB) from AD could be only attained in 70% of cases. We conclude that early symptomatology is the main clue for the diagnosis of pDLB. We identified by discriminant analysis a set of clinical diagnostic criteria similar to those proposed by the Consortium on Dementia With Lewy Bodies. Accuracy was excellent for the diagnosis of pDLB but only mediocre for separating AD+LB as well as the entire DLB group from AD.

Age of Onset↗
PubMed2000

Quantitative measurements of airflow inside a nuclear laboratory.

Dispersion dynamics of accidentally released radioactive aerosols or gases through laboratory workrooms are determined primarily by airflow, which impacts the level of human exposure and the response of air monitoring instrumentation. Therefore, applying conclusions derived from measurements of the fundamental aspects of airflow (velocity, direction, and turbulence) can lead to better protection of workers by suggesting appropriate locations for air monitoring and sampling. Historically, it has been very difficult to quantitatively measure these fundamental aspects of indoor airflow because of the low flow rates (often <10 cm s(-1)) and difficulties in quantitative measurement of three-dimensional airflow. Recent advances in sonic anemometry have enabled such measurements. For this study, a sonic anemometer was used that was capable of measuring airflow velocities with a sensitivity of about 0.5 cm s(-1) for each of the three-directional components. A sampling frequency of 1 Hz was selected to measure the fluctuations in the air velocity associated with turbulence and expressed in terms of "turbulence intensity." Point measurements of airflow velocities, directions, and turbulence intensities were made at 69 locations in a mechanically ventilated plutonium laboratory located at Los Alamos National Laboratory. Although the measurements were not made with workers present, all measurements were made at a height of 1.5 m, approximately the height of a worker's breathing zone (BZ). Velocities ranged from 8 cm s(-1) to 41 cm s(-1), with a median velocity of 18 cm s(-1). Percent turbulence intensities ranged from 13% to 57% with a median of 34%. The measured velocities and turbulence intensities in the laboratory showed that forced convective flows and turbulent eddy diffusion drive dispersion of released aerosols or gases. Results show that after an airborne release, mixing within the room can take minutes and may not always be complete. This is contrary to simplifying assumptions made by some risk modeling of accidentally released materials in a room. Our results also suggest that the mixing pattern would not be omnidirectional at most release locations, especially in the early stages of the release. Finally, airflow directions were upwards in breathing zones at most workstations. Because most releases in the plutonium laboratory occur at a height immediately below the BZ, the concentrated aerosol could be lifted into the BZ, followed by dispersal to the air monitor with the initiation of alarm.

Air Pollution, Radioactive↗
PubMed2003

Field dependence of the muon spin relaxation rate in MnSi.

Muon spin rotation/relaxation measurements have been performed in the itinerant helical magnet MnSi at ambient pressure and at 8.3 kbar. We have found the following: (a) the spin-lattice relaxation rate 1/T(1) shows divergence as T1T proportional, variant (T-T(c))(beta) with the power beta larger than 1 near T(c); (b) 1/T(1) is strongly reduced in an applied external field B(L) and the divergent behavior near T(c) is completely suppressed at B(L)> or =4000 G. We discuss that (a) is consistent with the self-consistent renormalization theory and reflects a departure from "mean-field" behavior, while (b) indicates selective suppression of spin fluctuations of the q=0 component by B(L).

Journal Article↗
PubMed2005

Responses of Baltic Sea ice and open-water natural bacterial communities to salinity change.

To investigate the responses of Baltic Sea wintertime bacterial communities to changing salinity (5 to 26 practical salinity units), an experimental study was conducted. Bacterial communities of Baltic seawater and sea ice from a coastal site in southwest Finland were used in two batch culture experiments run for 17 or 18 days at 0 degrees C. Bacterial abundance, cell volume, and leucine and thymidine incorporation were measured during the experiments. The bacterial community structure was assessed using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNA genes with sequencing of DGGE bands from initial communities and communities of day 10 or 13 of the experiment. The sea ice-derived bacterial community was metabolically more active than the open-water community at the start of the experiment. Ice-derived bacterial communities were able to adapt to salinity change with smaller effects on physiology and community structure, whereas in the open-water bacterial communities, the bacterial cell volume evolution, bacterial abundance, and community structure responses indicated the presence of salinity stress. The closest relatives for all eight partial 16S rRNA gene sequences obtained were either organisms found in polar sea ice and other cold habitats or those found in summertime Baltic seawater. All sequences except one were associated with the alpha- and gamma-proteobacteria or the Cytophaga-Flavobacterium-Bacteroides group. The overall physiological and community structure responses were parallel in ice-derived and open-water bacterial assemblages, which points to a linkage between community structure and physiology. These results support previous assumptions of the role of salinity fluctuation as a major selective factor shaping the sea ice bacterial community structure.

Colony Count, Microbial↗
PubMedDate not supplied

Intestinal motor function in irritable bowel syndrome.

Irritable bowel syndrome is widely considered to be associated with disordered gastro-intestinal motility. The evidence for a motor disorder in the colon and small intestine of patients with irritable bowel syndrome is reviewed. Results of myoelectric, motility and transit studies in both the colon and small intestine are inconsistent. Difficulties in interpreting colonic motility have led investigators to address the small intestine as a possible site of dysmotility. An increase in the number of clustered contractions in the proximal small intestine has been reported by some, but not all investigators. Methodological differences as well as patient selection, symptom severity and fluctuation may all contribute to discrepancies between the results of different studies. Motility disturbances may be present which are currently unrecognised due to an inadequate understanding of the propagation of colonic contractions, and of small intestinal contractions during phase II and postprandially. Whether the reported motor disturbances arise locally in the gut or originate from higher centres in the central nervous system has not been established.

Colon↗
PubMed1997

Isolated sleep paralysis, vivid dreams and geomagnetic influences: II.

This report describes a test of the hypothesis that significant changes in the ambient geomagnetic field are associated with altered normal nighttime dream patterns. Specifically, it was predicted that there would be a greater incidence of isolated sleep, paralysis or vivid dreams with abrupt rises and falls of geomagnetic activity. The author's (JC) and a second subject's (KC) daily reports of dream-recall were analyzed in the context of daily fluctuations of geomagnetic activity (K indices). Two analyses of variance indicated (i) significantly higher geomagnetic activity three days before a recorded isolated sleep paralysis event and (ii) significantly lower geomagnetic activity three days before an unusually vivid dream took place. Conversely, geomagnetic activity did not fluctuate significantly for randomly selected days. Testing a large sample over time is required for confirmation and extension of this work.

Dreams↗
PubMed1988

Friendship bonds in adolescence.

To assess the major motifs of interpersonal relations, achievement, and physical development influencing friendship formations, 204 adolescents at three grade levels responded to an open-ended questionnaire concerning friendship values. While the interpersonal category was salient at all grade levels for both boys and girls, it increased with time. A corresponding decrease for the achievement and physical attributes categories also emerged. Thus, friendship formations suggest a developmental trend in terms of selection, exhibiting the highest fluctuation by late adolescence.

Achievement↗
PubMed1984

[Vigilance--its EEG determination].

The definition of vigilance was based primarily on criteria of overt behaviour and concomitant electrographic patterns of functional states as well as on psychometrically tested performance. It turned out that the combination of well defined electroencephalographic activity patterns is an utile and reliable measure for the classification of different vigilance levels, even when there is no experimental testing of performance possible or the observation of behaviour misleading. We know today defined mixtures of characteristic regional EEG activities for the estimation on different levels of vigilance between supervigilance and subvigilance. There are however also deviations from regularly observed combinations of signs with dissociations between behaviour, performance and EEG-activity patterns. For the theory of vigilance one can use the analyses of topological and chronological organization of EEG-activities as starting point. Not only characteristic frequency mixtures are correlated with given vigilance levels; moreover the diffusion of regional activities interfering with all other regional activities builds up the socalled "vigilance profile". This profile varies with time slowly or quickly. The regular topological process distribution of activities is commonly the expression of a dominating mental process interfering with other submental processes. The chronological variations of vigilance profiles show their dynamism with transitions from fixed, strictly bound interest or "concentration" on selected objects to freely fluctuating interest, rapidly jumping from object to the other.

Alpha Rhythm↗
PubMed2004

Opposing natural selection from herbivores and pathogens may maintain floral-color variation in Claytonia virginica (Portulacaceae).

The maintenance of floral-color variation within natural populations is enigmatic because directional selection through pollinator preferences combined with random genetic drift should lead to the rapid loss of such variation. Fluctuating, balancing, and negative frequency-dependent selection mediated through pollinators have been identified as factors that may contribute to the maintenance of floral-color variation, and recently it has been suggested that indirect responses to selection on correlated characters through agents of selection other than pollinators may substantially shape the evolution of floral traits. Here, I provide empirical support for this latter view in Claytonia virginica (Portulacaceae) through a multiseason field study, a pollen supplementation study, and an artificial herbivory experiment. These studies show that most individuals fall into one of four discrete color classes, and suggest pollinator-mediated selection for increased floral redness in concurrent years. Floral color is also an indirect target of opposing directional selection via herbivores and pathogens that fluctuates through time. Taken together, these data suggest a novel mechanism by which floral-color variation may be maintained, and illustrate the importance of an inclusive, pluralistic view of selection when investigating the evolution of complex phenotypes.

Analysis of Variance↗
PubMed1980

Activity-dependent extracellular K+ fluctuations in canine Purkinje fibres.

Cardiac Purkinje fibres are important in cardiac electrophysiology and pathology due to their specialized role in the ventricular conducting system, and their properties as a second cardiac pacemaker. Changes in extracellular K+ activity (Ko) affect the conduction velocity and the natural automatic rate of the Purkinje fibre. Both anatomical and electrophysiological studies of the Purkinje fibres have demonstrated the possibility of Ko fluctuations in the narrow intercellular clefts. We investigated using K+ selective electrodes, the effect of the Ko fluctuations observed during activity in canine Purkinje fibres. Summation of Ko fluctuations during single action potentials leads to elevation of baseline Ko during rapid trains. However, unlike in ventricular muscle where depolarization is seen, membrane potential is non-automatic Purkinje fibres hyperpolarizes in response to rapid beating. Prolonged depletions of extracellular K+ following long periods of overdrive are associated with slowly changing membrane currents, which markedly influence automaticity, action potential duration, and membrane potential.

Action Potentials↗
PubMed2005

Redox fluctuation structures microbial communities in a wet tropical soil.

Frequent high-amplitude redox fluctuation may be a strong selective force on the phylogenetic and physiological composition of soil bacterial communities and may promote metabolic plasticity or redox tolerance mechanisms. To determine effects of fluctuating oxygen regimens, we incubated tropical soils under four treatments: aerobic, anaerobic, 12-h oxic/anoxic fluctuation, and 4-day oxic/anoxic fluctuation. Changes in soil bacterial community structure and diversity were monitored with terminal restriction fragment length polymorphism (T-RFLP) fingerprints. These profiles were correlated with gross N cycling rates, and a Web-based phylogenetic assignment tool was used to infer putative community composition from multiple fragment patterns. T-RFLP ordinations indicated that bacterial communities from 4-day oxic/anoxic incubations were most similar to field communities, whereas those incubated under consistently aerobic or anaerobic regimens developed distinctly different molecular profiles. Terminal fragments found in field soils persisted either in 4-day fluctuation/aerobic conditions or in anaerobic/12-h treatments but rarely in both. Only 3 of 179 total fragments were ubiquitous in all soils. Soil bacterial communities inferred from in silico phylogenetic assignment appeared to be dominated by Actinobacteria (especially Micrococcus and Streptomycetes), "Bacilli," "Clostridia," and Burkholderia and lost significant diversity under consistently or frequently anoxic incubations. Community patterns correlated well with redox-sensitive processes such as nitrification, dissimilatory nitrate reduction to ammonium (DNRA), and denitrification but did not predict patterns of more general functions such as N mineralization and consumption. The results suggest that this soil's indigenous bacteria are highly adapted to fluctuating redox regimens and generally possess physiological tolerance mechanisms which allow them to withstand unfavorable redox periods.

Aerobiosis↗