bluuebunny/crossref_metadata_2025 huggingface dataset:
Pacific Salmon Production Trends in Relation to Climate
Authors: Beamish Richard J. , Bouillon Daniel R.
Published: October 2008

Pink (Oncorhynchus gorbuscha), chum (O. keta), and sockeye salmon (O. nerka) represent approximately 90% of the commercial catch of Pacific salmon taken each year by Canada, Japan, the United States, and Russia. Annual all-nation catches of the three species and of each species, from 1925 to 1989, exhibited long-term parallel trends. National catches, in most cases, exhibited similar but weaker trends. The strong similarity of the pattern of the all-nation pink, chum, and sockeye salmon catches suggests that common events over a vast area affect the production of salmon in the North Pacific Ocean. The climate over the northern North Pacific Ocean is dominated in the winter and spring by the Aleutian Low pressure system. The long-term pattern of the Aleutian Low pressure system corresponded to the trends in salmon catch, to copepod production, and to other climate indices, indicating that climate and the marine environment may play an important role in salmon production.
Pumping Rates and Projected Filtering Impacts of Juvenile Zebra Mussels (Dreissena polymorpha) in Western Lake Erie
Authors: Bunt Christopher M. , Maclsaac Hugh J. , Sprules W. Gary
Published: October 2008

Small-bodied (2–11 mm), settled zebra mussels (Dreissena polymorpha Pallas) comprise up to 90% of individuals inhabiting reefs in western Lake Erie. We assessed pumping rates of these size classes of D. polymorpha by injecting an inert dye into inhalant filtering currents and monitoring exhalant flows using high-resolution videography. Pumping rates ranged between 0.20 and 4.45 mL∙ind−1∙h−1 and increased in relation to mussel shell length. Based on 1990 size–frequency distributions for reefs in western Lake Erie and our pumping rate – shell length regression, small settled D. polymorpha were theoretically capable of pumping between 39 and 96% of the water column daily. Small-bodied mussels inhabiting Sunken Chicken Reef were collectively capable of processing between 110 and 400% of the values previously reported for Daphnia. Recent changes in water quality in western Lake Erie could be primarily related to zebra mussel filtering activities, including those of small-bodied individuals.
Use of Lanthanide Elements to Mass Mark Juvenile Salmonids
Authors: Ennevor Bridget C. , Beames R. M.
Published: October 2008

Two experiments were conducted to evaluate the mass marking of coho salmon (Oncorhynchus kisutch) fry and smolts by the addition of lanthanide acetates to the water supply. The results demonstrated that lanthanides are absorbed from the water and are subsequently deposited in the vertebral column, otoliths, and scales of juvenile coho. Lanthanum and samarium applied at concentrations of 100 μg/L for 6 wk to fry resulted in the retention of detectable levels in bony tissues after 10.5 mo. When coho fry and smolts were exposed to various combinations of lanthanum and cerium at a total concentration in the water of 100 μg/L over a 4-wk period, residual mean amounts of lanthanides in the vertebral columns were greater in smolts than in fry.
Spatial Variations in Nutrient and Particulate Matter Concentrations in Pyramid Lake, Nevada, USA, during a Dry Period
Authors: Lebo Martin E. , Reuter John E. , Goldman Charles R. , Rhodes Cathryn L. , Vucinich Nancy , Mosely Dan
Published: October 2008

Spatial heterogeneity of nutrients, particulate matter, and chlorophyll were examined in Pyramid Lake during a dry period. In May 1991, variations in constituent concentrations were associat ed with shallow regions (chlorophyll), upwelling regions (nitrate), and river inflow (silicate and total P). However, only the spatial pattern of elevated silicate concentration near the mouth of the Truckee River was consistent throughout the year. Late-spring chlorophyll enrichment in shallow regions like the south basin appeared to be part of seasonal variations between the deep, central region of the lake and shallows possibly associated with light availability. During the study period, processes associated with strong winds appeared to be an important source of spatial heterogeneity. Profiles and spatial distributions of temperature and nitrate concentration during May 1991 indicated upwelling along the northwest and southwest margins of the lake. Examination of wind data for the region revealed that winds favorable for upwelling were common at Pyramid Lake, and temperature profiles along the north-south axis of the lake indicated additional upwelling events in June and September 1990. Strong winds also transport a large quantity of dust over the lake surface, which may be a major source of particle-bound P.
Stock Discrimination Using Otolith Shape Analysis
Authors: Campana Steven E. , Casselman John M.
Published: October 2008

Otolith shape has long been known to be species specific, but recent reports have pointed to its value as an indicator of stock identity. To test this hypothesis, all three pairs of otoliths were sampled from 2349 Atlantic cod (Gadus morhua) collected on spawning grounds throughout the northwest Atlantic. Otolith shape was determined with Fourier analysis and combined with measures of otolith area and perimeter. There were highly significant differences in otolith shape among most of the cod samples, but shape also differed among ages, sexes, and year-classes. The sagittal otoliths (largest pair) provided slightly better stock discrimination than did the lapillar or asteriscal otoliths. The first discriminant function was highly correlated with both fish and otolith growth rate, indicating that stock discrimination improved as the difference in stock-specific growth rate increased. Reevaluation of published studies on other species indicated that growth rate contributes more variation to regional differences in otolith shape than does stock origin. Differences in otolith shape among ages, sexes, and year-classes were also attributable to growth rate differences. To the extent that growth rates vary more between than within stocks, otolith shape analysis can provide an easily determined measure of stock identity.
Pollination mechanism of seed orchard interior spruce
Authors: Runions C. John , Catalano Glenda L. , Owens John N.
Published: October 2008

The pollination mechanism of interior spruce (white spruce, Piceaglauca (Moench) Voss, or Engelmann spruce, Piceaengelmannii Parry, and their hybrid) trees growing in a seed orchard was studied. Seed orchards are established in areas that are warmer and drier than the parent tree natural range. Hot, dry conditions during the pollination period adversely affected secretion of the pollination drop in unbagged seed cones as compared with bagged cones on the same tree. Unbagged cones remained open and apparently receptive for pollination for 5.3 ± 1.6 days (100 ± 31 h at >10°C), but pollination drops did not appear during this period. Pollination drops were secreted as cones began to close. The temporal correlation observed between cone closure and pollination drop secretion occurred as well in the higher relative humidity environment within pollination bags. Pollination drops in unbagged cones were smaller and did not persist as long as those in bagged cones. The micropylar arms, which capture pollen prior to pollination drop secretion, withered completely in unbagged cones before pollination drops were observed. Some withering of micropylar arms during cone receptivity is natural but complete withering means that the arms can not function in pollen capture throughout the period during which cones remain open. For this reason, supplemental mass pollination is best carried out early during the receptive period for trees growing in hot, dry environments. Overhead misting, used periodically during the receptive period to cool orchard trees, might slow seed-cone development and reduce micropylar arm withering, thereby increasing pollination success after supplemental mass pollination.
Canopy mortality and stand-scale change in a northern hemlock–hardwood forest
Authors: Parshall Tim
Published: October 2008

Ring-width patterns from 348 trees on a 5.25-ha mapped plot in the Sylvania Wilderness, Upper Michigan, were used to infer the pattern of canopy mortality for the past 140 years. Estimates of average canopy turnover rate (0.54%/year) and average canopy residence time (186 years) are similar to other estimates for the region. The temporal pattern of release events detected in the cores is closely related to the occurrence of extreme drought with sugar maple (Acersaccharum Marsh.) trees showing increased growth in the years directly following drought and eastern hemlock (Tsugacanadensis (L.) Carr.) trees showing increased growth 3–4 years following drought. Drought seems to be synchronizing canopy recruitment by influencing the temporal pattern of canopy mortality. In particular, 22% of all sampled stems show a response to canopy turnover during the 1930s and a large portion of the recruitment consisted of sugar maple stems originating in gaps. Individuals of this sugar maple cohort are clustered up to 30–40 m. Along the border between the hemlock and hardwood stands, remnant hemlock logs are present beneath these sugar maple clusters suggesting that canopy replacement of hemlock by sugar maple has occurred. Diameter distributions of stems indicate that sugar maple is regenerating in hardwood stands and in areas of mixed species composition. In contrast, smaller size classes of hemlock are conspicuously absent from areas of mixed species composition and are restricted to the hemlock stand. In this hemlock–hardwood forest mosaic, sugar maple has been slowly increasing in abundance at the expense of hemlock, gradually increasing the extent of the hardwood patch.
Variations in radial growth of declining old-growth stands of Abiesamabilis after tephra deposition from Mount St. Helens
Authors: Segura Gerardo , Hinckley Thomas M. , Brubaker Linda B.
Published: October 2008

Radial growth trends of old-growth mixed conifer forests were evaluated in areas impacted by tephra deposition from the 1980 eruption of Mount St. Helens, Washington. These areas were characterized by a crown decline in Abiesamabilis (Dougl.)Forbes (Pacific silver fir), associated with the long-term tephra retention by foliage. Post-1980 growth changes of A. amabilis were quantified using standard dendrochronological techniques in stands covering a range of crown decline conditions, amount of tephra deposited, elevation, and species composition. Time-series models revealed autocorrelations in the growth trend of all species at all sites. Intervention analysis quantified posteruption radial growth changes and significantly improved the description of the original time series models. Growth reductions of A. amabilis were generally consistent with the mean crown decline conditions of individual sites. However, the magnitude of growth reductions did not correspond closely to the decline condition of the stand. Abiesamabilis experienced significant post-1980 growth reductions in sites with high crown decline, but no growth changes were detected in sites with low decline. Tsugaheterophylla (Raf.)Sarg.(western hemlock) and Pseudotsugamenziesii (Mirb.) Franco (Douglas-fir), which consistently occurred with A. amabilis in the study area, did either not experience growth reductions or had significant positive growth after 1981. This positive post-disturbance growth could be explained as a compensatory response to the appreciable growth decline of A. amabilis.
Stem growth responses of declining mature Abiesamabilis trees after tephra deposition from Mount St. Helens
Authors: Segura Gerardo , Hinckley Thomas M. , Oliver Chadwick D.
Published: October 2008

Stem analysis of mature Abiesamabilis (Dougl.) Forbes (Pacific silver fir) trees was used to analyze patterns of radial growth in areas of southwestern Washington where this species is experiencing a severe crown decline associated with heavy tephra deposition from the 1980 eruption of Mount St. Helens. Reductions in stem growth after 1980 appeared to be related to the severity of crown damage. The largest reductions in cross-sectional area increment exceeded 50% and extended along most of the stem. An increase in stem growth in the upper crown was common among declining trees. This zone coincided with a portion of the crown that has experienced vigorous and rapid growth since 1980. The role of this recovery zone on subsequent tree recovery is discussed. Decline or recovery of trees appeared independent of crown class per se. Reductions in radial growth of declining trees tended to be more pronounced at breast height, suggesting that estimations of whole-stem growth based on breast height measurements would overestimate growth losses.
Comparison of Gremmeniellaahietina historical damage to Scots pines
Authors: Kaitera Juha A. , Jalkanen Risto E.
Published: October 2008

Fifteen Scots pine (Pinussylvestris L.) trees that were slightly, moderately, or severely damaged by Gremmeniellaabietina (Lagerb.) Morelet were felled in northern Finland to determine the disease history of the stand. The annual level of damage was determined by counting the scars and cankers on all the first-order branches. Annual branch leader changes (dead shoots), branch mortality, and attacks caused by shoot beetles, Tomicus spp., were also determined. Most of the G. abietina damage occurred in the middle and late 1980s. However, the damage occurred at low levels in the stand as early as in the 1940s, demonstrating that the history of the disease followed the established pattern noticed earlier in eastern Lapland. For slightly damaged trees, most damage occurred in the mid-1980s, while for their severely damaged counterparts most damage occurred in the late 1980s.
Predicting the effects of site preparation and protection on development of young Douglas-fir plantations
Authors: Knowe Steven A. , Stein William I.
Published: October 2008

Diameter prediction models based on the Weibull distribution function and stand-table projection models based on changes in relative diameter were developed for 2- to 10-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations. Both modeling approaches incorporated the effects of site preparation, animal protection, and competing vegetation. The diameter distribution approach is appropriate when information on initial diameters is not available. The stand-table projection approach may be applied when tree diameters in a plantation are measured two or more growing seasons after planting. At young ages, the stand-table approach provided more accurate representation of observed diameter distributions than the diameter distribution approach. At age 10 the two methods provided comparable diameter distributions. The equations derived for predicting survival, height growth of dominant trees, height–diameter relationships, and the development of woody vegetation over time will facilitate the study and comparison of stand structure and dynamics after various site-preparation and animal-protection treatments.
Estimating condition areas and boundary lengths in sample plots with mapped designs
Authors: Schreuder H.T. , Gregoir T.G.
Published: October 2008

Currently the U.S. Forest Service is implementing different versions of sampling a mapped cluster of subplots on the ground for estimating forest parameters. Biased estimators of lengths of boundaries between forest conditions and unbiased but inefficient estimators of areas in these conditions are available. Improved estimators are given for these ecological parameters for each subplot (and hence for the population) by measuring some additional distances to the boundary and then using either easily implemented triangulation approximation techniques, grid counting, and line transect sampling, or importance sampling. The triangulation approximation techniques are preferred at this time for operational surveys such as those conducted by the U.S. Forest Service. Boundary lengths and areas and the co-location frequency of various forest conditions, ecotones, or transition zones have traditionally not been of interest in forest surveys but can now be objectively and reliably estimated with the new mapped designs.
Sapwood–leaf area prediction equations for multi-aged ponderosa pine stands in western Montana and central Oregon
Authors: O'Hara Kevin L. , Valappil Narayanan I.
Published: October 2008

Ponderosa pine (Pinusponderosa Dougl. ex Laws.) frequently grows in pure, multi-aged stands throughout its range. Sapwood–leaf area prediction equations were developed for multi-aged, multi-strata ponderosa pine stands in western Montana and central Oregon. No significant differences were found between equations for trees from lower or upper strata, or between equations for all trees and equations for upper or lower strata trees in either study location. These results indicate overstory ponderosa pine trees do not require significantly greater sapwood conducting tissue per unit of leaf area than understory trees. Single variable models using only sapwood area at breast height are recommended.
DEVELOPMENT OF SAMPLE PREPARATION METHOD FOR HONEY ANALYSIS USING PIXE
Authors: SAITOH KATSUMI , CHIBA KEIKO , SERA KOICHIRO
Published: October 2008

We developed an original preparation method for honey samples (samples in paste-like state) specifically designed for PIXE analysis. The results of PIXE analysis of thin targets prepared by adding a standard containing nine elements to honey samples demonstrated that the preparation method bestowed sufficient accuracy on quantitative values. PIXE analysis of 13 kinds of honey was performed, and eight mineral components ( Si , P , S , K , Ca , Mn , Cu and Zn ) were detected in all honey samples. The principal mineral components were K and Ca , and the quantitative value for K accounted for the majority of the total value for mineral components. K content in honey varies greatly depending on the plant source. Chestnuts had the highest K content. In fact, it was 2–3 times that of Manuka, which is known as a high quality honey. K content of false-acacia, which is produced in the greatest abundance, was 1/20 that of chestnuts.
APPLICATION OF MICRO-PIXE ANALYSIS FOR A MIGRATION HISTORY STUDY OF HUCHO PERRYI FOCUSED ON STRONTIUM DISTRIBUTION IN FISH SCALES
Authors: SUZUKI K. , YOSHITOMI T. , KAWAGUCHI Y. , EDO K. , HOMMA-TAKEDA S. , ISHIKAWA T. , ISO H. , IMASEKI H.
Published: October 2008

Sakhalin taimen, Hucho perryi, is one of the largest freshwater fish in Japan, where it is close to extinction because of indiscriminate fishing, water pollution, and river construction. Interpretable ecological information about the species, however, is scarce. We examined the migration history of H. perryi by analysis of strontium ( Sr ) content in fish scales using inductively coupled plasma mass spectrometry and Sr distributions associated with ridges (growth lines) in the scales, with micro-beam scanning PIXE (micro-PIXE) analyses. Sr levels in the scales of H. perryi collected along the Sarufutsu coast were higher than those of salmonid collected at Shumarinai, a freshwater lake. Micro-PIXE line analyses showed that the scale Sr values of the Shumarinai Lake samples remained consistently low from the edge toward the core of the scales. The Sr values from the Sarufutsu coast samples remained relatively high from the edge toward the core; Sr levels from second to fourth position from the edge were about ten times higher than the mean levels of Shumarinai Lake samples. These results suggested that H. perryi from the Sarufutsu Coast had experienced the marine environment.
ELEMENTAL IMAGING IN PANCREAS OF IMMATURE RATS BY MICRO PIXE ANALYSIS
Authors: HOMMA-TAKEDA SHINO , INOUE MIYUKI I , UENO SHUNJI , ISO HIROYUKI , ISHIKAWA TAKAHIRO , NISHIMIRA YOSHIKAZU , IMASEKI HITOSHI , YUKAWA MASAE , SHIMADA YOSHIYA
Published: October 2008

The pancreas is a large gland capable of both exocrine and endocrine functions; it releases digestive enzymes into the duodenum and hormones into the bloodstream. It is known that Zn plays a key role in the synthesis and action of insulin, one of the pancreatic hormones. However, elemental profiles of the pancreas are not well understood. Here, we examined precise distributions of elements in the pancreas of newborn and young rats by scanning microbeam particle induced X-ray emission (micro PIXE) analysis and compared the results to those of adult animals.

Micro PIXE analysis revealed a site-specific distribution of elements in the two major compartments of the pancreas, the exocrine (acinar tissue) and the endocrine portions (islets of Langerhans). The Zn concentrations in the pancreas of the newborn (six days), young (three weeks), and adult rats (ten weeks) were 11.3 ± 2.5 μ g / g wet weight, 7.26 ± 0.36 μ g / g wet weight, and 10.8 ± 1.1 μ g / g wet weight, respectively. In newborn and young rats, Zn was detected mainly in the islets of Langerhans, while K and P were distributed more to the acinar tissues than the islet cells. The site-specific distributions of K , P , and Zn were more obvious in the adult animals.
SERUM TRACE ELEMENTS AS NUTRITIONAL MARKERS IN A CASE WITH ACUTE AORTIC DISSECTION
Authors: MIURA Y. , SUWABE A. , TAWARA M. , ENDO R. , IKEDA K. , SERA K.
Published: October 2008

Serum trace elements were analyzed by PIXE method in a patient with acute aortic dissection during the supportive process by a Nutrition support team (NST). The patient was a 53-year old male who suffered from acute aortic dissection on March 1, 2007. He received emergent Bentall operation and bow pars total displacement. Since he suffered from diarrhea as a result of hypoalbuminemia and bowel dysfunction, enteral nutrition was not sufficient to maintain adequate intake. Therefore, we also used parenteral nutrition until the 97th disease day. Afterwards, the patient managed only with enteral nutrition. We measured serum trace elements during these periods. Serum trace elements such as Fe , Zn and Se were preserved within normal ranges. On the other hand, Cu gradually decreased until the 54th disease day (44 μg/l) and stayed in the lower levels around the detection limit until the 109th disease day. Thereafter, Cu slightly increased and reached 117 μg/l on the 131st disease day (reference range of serum Cu in adult males: 700~1,300 μ g/l ). It was suggested that the serum levels of these trace elements might reflect the nutritional stages of the patient and could be useful as clinical markers for nutritional therapies.
MERCURY DISTRIBUTION BY MICRO PIXE ANALYSIS IN STENOPSYCHE MARMORATA EXPOSED TO MERCURIC CHLORIDE
Authors: YOSHITOMI TOMOYASU , YAGINUMA NAOKI , ISO HIROYUKI , ISHIKAWA TAKAHIRO , IMASEKI HITOSHI , HOMMA-TAKEDA SHINO
Published: October 2008

Aquatic insects, such as caddisflies, are used as reference organisms for water pollution. The precise distribution of contaminated metals in the insect, however, remains unknown. In this study, we used micro PIXE analysis to examine mercury distribution in Stenopsyche marmorata, a typical caddisfly, exposed to mercuric chloride. The mercury level in the caddisflies after exposure to mercuric chloride at 1 mg/L for 5 days was 93.3 ± 25.0 μ g/g wet weight. Micro PIXE analysis also revealed a site-specific distribution of mercury in the insects. Mercury was high in the digestive tract, where it was localized in the basement membrane and the peritrophic membrane. Mercury was also detected in the tissue surrounding the digestive tract. Further examination of the tissue identified mercury in the fat body but not in the silk gland.
A FOUR-BY-FOUR MATRIX EIGENVALUE PROBLEM, RELATED HIERARCHY OF LAX INTEGRABLE EQUATIONS AND THEIR HAMILTONIAN STRUCTURES
Authors: XU XI-XIANG , YANG HONG-XIANG , CAO WEI-LI
Published: October 2008

Starting from a new four-by-four matrix eigenvalue problem, a hierarchy of Lax integrable evolution equations with four potentials is derived. The Hamiltonian structures of the resulting hierarchy are established by means of the generalized trace identity. The Liouville integrability for the hierarchy of the resulting Hamiltonian equations is proved.
ENTROPY GROWTH AND DEGRADATION OF ENTANGLEMENT DUE TO DAMPING OF THE ATOMIC DECAY IN THE JC MODEL
Authors: HESSIAN H. A.
Published: October 2008

In this presentation, we considered the atomic decay (but not for the cavity) for a two-level atom interacting with a single mode of electromagnetic field. The exact solution of the master equation in the case of a high-Q cavity with atomic decay is found. The effects of the atomic damping for a thermal reservoir on the temporal evolution of partial entropies of the atom or the field, and the total entropy as a quantitative entanglement, was measured. The degree of entanglement, through the sum of the negative eigenvalues of the partially transposed density matrix and the negative mutual information, has been studied and compared with other measures.
NANOSTRUCTURED CARBON NITRIDE FILMS DEPOSITED USING THE LOW-COST PENNING DISCHARGE PLASMA-SPUTTERING TECHNIQUE
Authors: ZHANG H. X. , LI H. Y. , FENG P. X.
Published: October 2008

Nanostructured carbon nitride films have peen synthesized by using a low-cost Penning discharge (PD) plasma-sputtering source. The influences of different working gas pressures on the surface morphologies, chemical compositions, bond structures, and mechanical properties of deposited carbon nitride thin films have been investigated using Scanning probe microscope (SPM), X-ray photoelectron spectroscopy (XPS) measurements, Raman spectroscopes, and nanoindentation measurements, respectively.

SPM and XPS data indicate the variations of the root-mean-square roughness (R RMS ) of the samples surfaces from 7.5 nm, 11.4 nm, to 17.7 nm, and an increase of sp2 fraction inside the films from 22.8% to 26.9% with an up-shift of the deposition gas pressures. In contrast, the sp3 content decreases from 17.5% to 11.8%. The shifts of D and G peaks and variations of band intensity (ID/IG) have been observed in Raman spectra. The hardness of samples is reduced with increasing N2 partial pressure applied during film deposition.
SOLUTION OF THE INVERSE SCATTERING PROBLEM AT FIXED ENERGY FOR POTENTIALS BEING ZERO BEYOND A FIXED RADIUS
Authors: HORVÁTH MIKLÓS , APAGYI BARNABÁS
Published: October 2008

Based on the relation between the m-function and the spectral function we construct an inverse quantum scattering procedure at fixed energy which can be applied to spherical radial potentials vanishing beyond a fixed radius a. To solve the Gelfand–Levitan–Marchenko integral equation for the transformation kernel, we determine the input symmetrical kernel by using a minimum norm method with moments defined by the input set of scattering phase shifts. The method applied to the box and Gauss potentials needs further practical developments regarding the treatment of bound states.
NOTES ON THE DISTRIBUTION OF PHASE SHIFTS
Authors: HORVÁTH MIKLÓS
Published: October 2008

We consider three-dimensional inverse scattering with fixed energy for which the spherically symmetrical potential is nonvanishing only in a ball. We give exact upper and lower bounds for the phase shifts. We provide a variational formula for the Weyl–Titchmarsh m-function of the one-dimensional Schrödinger operator defined on the half-line.
QUANTUM INVERSE SCATTERING PROBLEM FOR COUPLED CHANNELS
Authors: APAGYI BARNABÁS , SCHEID WERNER
Published: October 2008

The article gives a concise review on methods for solving the inverse scattering problem of coupled reaction channels in quantum mechanics at fixed energy and presents specific applications to nuclear reactions. Two methods are considered, namely the Newton–Sabatier method and an approximate method based on the first Born approximation. Examples with artificial coupling potentials are shown to provide successful tests of both the methods. Further developments of the coupled channel inverse problem at fixed energy are needed for manifold applications in various fields of physics.
INVERSE BORN APPROXIMATION FOR THE GENERALIZED NONLINEAR SCHRÖDINGER OPERATOR IN TWO DIMENSIONS
Authors: SEROV VALERIY
Published: October 2008

This work deals with the inverse scattering problems for the two-dimensional Schrödinger equation [Formula: see text] with a power-like nonlinearity, where the real-valued unknown functions αlon belong to [Formula: see text] with certain special behaviour at infinity. We prove Saito's formula which implies the uniqueness result and a representation formula for a sum of the functions αlin the sense of tempered distributions. What is more, we prove that the leading order singularities of this sum can be obtained exactly by the inverse Born approximation method from general scattering data at arbitrarily large energies. Especially, we show for the functions in Lp, for certain values of p, that the approximation agrees with the true sum up to the functions from the Sobolev spaces. In particular, for the sum being the characteristic function of a smooth bounded domain this domain is uniquely determined by this scattering data.
EXACTLY-SOLVABLE COUPLED-CHANNEL MODELS FROM SUPERSYMMETRIC QUANTUM MECHANICS
Authors: SPARENBERG JEAN-MARC , PUPASOV ANDREY M. , SAMSONOV BORIS F. , BAYE DANIEL
Published: October 2008

Starting from a system of N radial Schrödinger equations with a vanishing potential and finite threshold differences between the channels, a coupled N × N exactly-solvable potential model is obtained with the help of a single non-conservative supersymmetric transformation. The obtained potential matrix, which subsumes a result obtained in the literature, has a compact analytical form, as well as its Jost matrix. It depends on N(N + 1)/2 unconstrained parameters and on one upper-bounded parameter, the factorization energy. For N = 2, previous results are reviewed, in particular regarding the number of bound states and resonances of the potential. A schematic inverse problem with one resonance is considered.
DIFFRACTION BY EDGES
Authors: VASY ANDRÁS
Published: October 2008

In these expository notes we explain the role of geometric optics in wave propagation on domains or manifolds with corners or edges. Both the propagation of singularities, which describes where solutions of the wave equation may be singular, and the diffractive improvement under non-focusing hypotheses, which states that in certain places the diffracted wave is more regular than a priori expected, is described. In addition, the wave equation on differential forms with natural boundary conditions, which in particular includes a formulation of Maxwell's equations, is studied.
The Contribution of Epithelial Sodium Channels to Alveolar Function in Health and Disease
Authors: Eaton Douglas C. , Helms My N. , Koval Michael , Bao Hui Fang , Jain Lucky
Published: October 2008

Amiloride-sensitive epithelial sodium channels (ENaC) play an important role in lung sodium transport. Sodium transport is closely regulated to maintain an appropriate fluid layer on the alveolar surface. Both alveolar type I and II cells have several different sodium-permeable channels in their apical membranes that play a role in normal lung physiology and pathophysiology. In many epithelial tissues, ENaC is formed from three subunit proteins: α, β, and γ ENaC. Part of the diversity of sodium-permeable channels in lung arises from assembling different combinations of these subunits to form channels with different biophysical properties and different mechanisms for regulation. Thus, lung epithelium has enormous flexibility to alter the magnitude of salt and water transport. In lung, ENaC is regulated by many transmitter and hormonal agents. Regulation depends upon the type of sodium channel but involves controlling the number of apical channels and/or the activity of individual channels.
Short-term effects of thyroid hormones on Na+-K+-ATPase activity of chick embryo hepatocytes during development: focus on signal transduction
Authors: Scapin Sergio , Leoni Silvia , Spagnuolo Silvana , Fiore Anna Maria , Incerpi Sandra
Published: October 2008

Nongenomic effects of thyroid hormones on Na+-K+-ATPase activity were studied in chick embryo hepatocytes at two different developmental stages, 14 and 19 days of embryonal age, and the signal transduction pathways involved were characterized. Our data showed the following. 1) 3,5,3′-Triiodo-l-thyronine (T3) and 3,5-diiodo-l-thyronine (3,5-T2) rapidly induced a transient inhibitory effect on the Na+-K+-ATPase; the extent and duration depended on the developmental age of the cells. 2) 3,5-T2 behaved as a true hormone and fully mimicked the effect of T3. 3) Thyroxine had no effect at any of the developmental stages. 4) The inhibition of Na+-K+-ATPase was mediated by activation of protein kinase A, protein kinase C, and phosphoinositide 3-kinase, suggesting several modes of modulation of ATPase activity through phosphorylation at different sites. 5) The MAPK pathway did not seem to be involved in the early phase of hormone treatment. 6) The nonpermeant analog T3-agarose inhibited Na+-K+-ATPase activity in the same way as T3, confirming that hormone signaling initiated at a receptor on the plasma membrane. From these results, it can be concluded that the cell response mechanisms change rapidly and drastically within the early phase of embryo growth. The differences found at the two stages probably reflect the different roles of thyroid hormones during development and differentiation.
Divergent cell signaling after short-term intensified endurance training in human skeletal muscle
Authors: Benziane Boubacar , Burton Timothy J. , Scanlan Brendan , Galuska Dana , Canny Benedict J. , Chibalin Alexander V. , Zierath Juleen R. , Stepto Nigel K.
Published: October 2008

Endurance training represents one extreme in the continuum of skeletal muscle plasticity. The molecular signals elicited in response to acute and chronic exercise and the integration of multiple intracellular pathways are incompletely understood. We determined the effect of 10 days of intensified cycle training on signal transduction in nine inactive males in response to a 1-h acute bout of cycling at the same absolute workload (164 ± 9 W). Muscle biopsies were taken at rest and immediately and 3 h after the acute exercise. The metabolic signaling pathways, including AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR), demonstrated divergent regulation by exercise after training. AMPK phosphorylation increased in response to exercise (∼16-fold; P < 0.05), which was abrogated posttraining ( P < 0.01). In contrast, mTOR phosphorylation increased in response to exercise (∼2-fold; P < 0.01), which was augmented posttraining ( P < 0.01) in the presence of increased mTOR expression ( P < 0.05). Exercise elicited divergent effects on mitogen-activated protein kinase (MAPK) pathways after training, with exercise-induced extracellular signal-regulated kinase (ERK) 1/2 phosphorylation being abolished ( P < 0.01) and p38 MAPK maintained. Finally, calmodulin kinase II (CaMKII) exercise-induced phosphorylation and activity were maintained ( P < 0.01), despite increased expression (∼2-fold; P < 0.05). In conclusion, 10 days of intensified endurance training attenuated AMPK, ERK1/2, and mTOR, but not CaMKII and p38 MAPK signaling, highlighting molecular pathways important for rapid functional adaptations and maintenance in response to intensified endurance exercise and training.
Effects of high-intensity training on muscle lactate transporters and postexercise recovery of muscle lactate and hydrogen ions in women
Authors: Bishop David , Edge Johann , Thomas Claire , Mercier Jacques
Published: October 2008

The purpose of this study was to investigate the effects of high-intensity interval training (3 days/wk for 5 wk), provoking large changes in muscle lactate and pH, on changes in intracellular buffer capacity (βmin vitro), monocarboxylate transporters (MCTs), and the decrease in muscle lactate and hydrogen ions (H+) after exercise in women. Before and after training, biopsies of the vastus lateralis were obtained at rest and immediately after and 60 s after 45 s of exercise at 190% of maximal O2 uptake. Muscle samples were analyzed for ATP, phosphocreatine (PCr), lactate, and H+; MCT1 and MCT4 relative abundance and βmin vitro were also determined in resting muscle only. Training provoked a large decrease in postexercise muscle pH (pH 6.81). After training, there was a significant decrease in βmin vitro (−11%) and no significant change in relative abundance of MCT1 (96 ± 12%) or MCT4 (120 ± 21%). During the 60-s recovery after exercise, training was associated with no change in the decrease in muscle lactate, a significantly smaller decrease in muscle H+, and increased PCr resynthesis. These results suggest that increases in βmin vitro and MCT relative abundance are not linked to the degree of muscle lactate and H+ accumulation during training. Furthermore, training that is very intense may actually lead to decreases in βmin vitro. The smaller postexercise decrease in muscle H+ after training is a further novel finding and suggests that training that results in a decrease in H+ accumulation and an increase in PCr resynthesis can actually reduce the decrease in muscle H+ during the recovery from supramaximal exercise.
Chronic myocardial infarction induces phenotypic and functional remodeling in the guinea pig cardiac plexus
Authors: Hardwick Jean C. , Southerland E. Marie , Ardell Jeffrey L.
Published: October 2008

Chronic myocardial infarction (CMI) is associated with remodeling of the ventricle and evokes adaption in the cardiac neurohumoral control systems. To evaluate the remodeling of the intrinsic cardiac nervous system following myocardial infarction, the dorsal descending coronary artery was ligated in the guinea pig heart and the animals were allowed to recover for 7–9 wk. Thereafter, atrial neurons of the intrinsic cardiac plexus were isolated for electrophysiological and immunohistochemical analyses. Intracellular voltage recordings from intrinsic cardiac neurons demonstrated no significant changes in passive membrane properties or action potential configuration compared with age-matched controls and sham-operated animals. The intrinsic cardiac neurons from chronic infarcted hearts did demonstrate an increase in evoked action potential (AP) frequency (as determined by the number of APs produced with depolarizing stimuli) and an increase in responses to exogenously applied histamine compared with sham and age-matched controls. Conversely, pituitary adenylate cyclase-activating polypeptide (PACAP)-induced increases in intrinsic cardiac neuron-evoked AP frequency were similar between control and CMI animals. Immunohistochemical analysis demonstrated a threefold increase in percentage of neurons immunoreactive for neuronal nitric oxide synthase (NOS) in CMI animals compared with control and the additional expression of inducible NOS by some neurons, which was not evident in control animals. Finally, the density of mast cells within the intrinsic cardiac plexus was increased threefold in preparations from CMI animals. These results indicate that CMI induces a differential remodeling of intrinsic cardiac neurons and functional upregulation of neuronal responsiveness to specific neuromodulators.
Enteral nutrients potentiate the intestinotrophic action of glucagon-like peptide-2 in association with increased insulin-like growth factor-I responses in rats
Authors: Liu Xiaowen , Murali Sangita G. , Holst Jens J. , Ney Denise M.
Published: October 2008

Glucagon-like peptide-2 (GLP-2) is a nutrient-dependent, intestinotrophic hormone derived from posttranslational processing of proglucagon in the distal bowel. GLP-2 is thought to act through indirect mediators, such as IGF-I. We investigated whether intestinal expression of GLP-2 and IGF-I system components are increased with the mucosal growth induced by enteral nutrient (EN) and/or a low dose of GLP-2 in parenterally fed rats. Rats were randomized to four treatment groups using a 2×2 design and maintained with parenteral nutrition (PN) for 7 days: PN alone, EN, GLP-2, and EN+GLP-2; n = 7–9. The two main treatment effects are ±GLP-2 (100 μg·kg body wt−1·day−1) and ±EN (43% of energy needs, days 4–6). Combination treatment with EN+GLP-2 induced synergistic intestinal growth in ileum, resulting in greater mucosal cellularity, sucrase segmental activity, and gain of body weight (EN×GLP-2, P < 0.04). In addition, EN+GLP-2 induced a significant 28% increase in plasma concentration of bioactive GLP-2, a significant 102% increase in ileal proglucagon mRNA with no change in ileal dipeptidyl peptidase-IV (DPP-IV) specific activity, and significantly reduced plasma DPP-IV activity compared with GLP-2. This indicates that EN potentiates the intestinotrophic action of GLP-2. Proliferation of enterocytes due to GLP-2 infusion was associated with greater expression of ileal proglucagon, GLP-2 receptor, IGF-I, IGF binding protein-3 mRNAs, and greater IGF-I peptide concentration in ileum ( P < 0.032). Ileal IGF-I mRNA was positively correlated with expression of proglucagon, GLP-2R, and IGFBP-5 mRNAs ( R2 = 0.43–0.56, P < 0.0001). Our findings support the hypothesis that IGF-I is one of the downstream mediators of GLP-2 action in a physiological model of intestinal growth.
Development and characterization of a novel rat model of type 2 diabetes mellitus: the UC Davis type 2 diabetes mellitus UCD-T2DM rat
Authors: Cummings Bethany P. , Digitale Erin K. , Stanhope Kimber L. , Graham James L. , Baskin Denis G. , Reed Benjamin J. , Sweet Ian R. , Griffen Steven C. , Havel Peter J.
Published: October 2008

The prevalence of type 2 diabetes (T2DM) is increasing, creating a need for T2DM animal models for the study of disease pathogenesis, prevention, and treatment. The purpose of this project was to develop a rat model of T2DM that more closely models the pathophysiology of T2DM in humans. The model was created by crossing obese Sprague-Dawley rats with insulin resistance resulting from polygenic adult-onset obesity with Zucker diabetic fatty-lean rats that have a defect in pancreatic β-cell function but normal leptin signaling. We have characterized the model with respect to diabetes incidence; age of onset; longitudinal measurements of glucose, insulin, and lipids; and glucose tolerance. Longitudinal fasting glucose and insulin data demonstrated progressive hyperglycemia (with fasting and fed glucose concentrations >250 and >450 mg/dl, respectively) after onset along with hyperinsulinemia resulting from insulin resistance at onset followed by a progressive decline in circulating insulin concentrations, indicative of β-cell decompensation. The incidence of diabetes in male and female rats was 92 and 43%, respectively, with an average age of onset of 6 mo in males and 9.5 mo in females. Results from intravenous glucose tolerance tests, pancreas immunohistochemistry, and islet insulin content further support a role for β-cell dysfunction in the pathophysiology of T2DM in this model. Diabetic animals also exhibit glycosuria, polyuria, and hyperphagia. Thus diabetes in the UC Davis-T2DM rat is more similar to clinical T2DM in humans than in other existing rat models and provides a useful model for future studies of the pathophysiology, treatment, and prevention of T2DM.
Failure to upregulate the adenosine2Areceptor-epoxyeicosatrienoic acid pathway contributes to the development of hypertension in Dahl salt-sensitive rats
Authors: Liclican Elvira L. , McGiff John C. , Falck John R. , Carroll Mairéad A.
Published: October 2008

Adenosine-activated renovascular dilatation in Sprague-Dawley (SD) rats is mediated by stimulating adenosine2Areceptors (A2AR), which is linked to epoxyeicosatrienoic acid (EET) synthesis. The A2AR-EET pathway is upregulated by high salt (HS) intake in normotensive SD rats. Because this pathway is antipressor, we examined the role of the A2AR-EET pathway in Dahl salt-sensitive (SS) rats. Male Dahl salt-resistant (SR) and SS rats were fed either HS (8.0% NaCl) or normal salt (NS; 0.4% NaCl) diet for 7 days. On day 8, isolated kidneys were perfused with Krebs-Henseleit buffer containing indomethacin and NG-nitro-l-arginine methyl ester and preconstricted with phenylephrine. Bolus injections of the stable adenosine analog 2-chloroadenosine (2-CA; 0.1–20 μg) elicited dose-dependent dilation in both Dahl SR and SS rats. Dahl SR rats fed a HS diet demonstrated a greater renal vasodilator response to 10 μg of 2-CA, as measured by the reduction in renal perfusion pressure, than that of Dahl SR rats fed a NS diet (−104 ± 6 vs. −77 ± 7 mmHg, respectively; P < 0.05). In contrast, Dahl SS rats did not exhibit a difference in the vasodilator response to 2-CA whether fed NS or HS diet (96 ± 6 vs. 104 ± 13 mmHg in NS- and HS-fed rats, respectively). In Dahl SR but not Dahl SS rats, HS intake significantly increased purine flux, augmented the protein expression of A2AR and the cytochrome P-450 2C23 and 2C11 epoxygenases, and elevated the renal efflux of EETs. Thus the Dahl SR rat is able to respond to HS intake by recruiting EET formation, whereas the Dahl SS rat appears to have exhausted its ability to increase EET synthesis above the levels observed on NS intake, and this inability of Dahl SS rats to upregulate the A2AR-EET pathway in response to salt loading may contribute to the development of salt-sensitive hypertension.
Development of Theta Rhythmicity in Entorhinal Stellate Cells of the Juvenile Rat
Authors: Burton Brian G. , Economo Michael N. , Lee G. Jenny , White John A.
Published: October 2008

Mature stellate cells of the rat medial entorhinal cortex (EC), layer II, exhibit subthreshold membrane potential oscillations (MPOs) at theta frequencies (4–12 Hz) in vitro. We find that MPOs appear between postnatal days 14 (P14) and 18 (P18) but show little further change by day 28+ (P28–P32). To identify the factors responsible, we examined the electrical responses of developing stellate cells, paying attention to two currents thought necessary for mature oscillation: the h current Ih, which provides the slow rectification required for resonance; and a persistent sodium current INaP, which provides amplification of resonance. Responses to injected current revealed that P14 cells were often nonresonant with a relatively high resistance. Densities of Ih and INaP both rose by about 50% from P14 to P18. However, Ih levels fell to intermediate values by P28+. Given the nonrobust trend in Ih expression and a previously demonstrated potency of even low levels of Ih to sustain oscillation, we propose that resonance and MPOs are limited at P14 more by low levels of INaP than of Ih. The relative importance of INaP for the development of MPOs is supported by simulations of a conductance-based model, which also suggest that general shunt conductance may influence the precise age when MPOs appear. In addition to our physiological study, we analyzed spine densities at P14, P18, and P28+ and found a vigorous synaptogenesis across the whole period. Our data predict that functions that rely on theta rhythmicity in the hippocampal network are limited until at least P18.