bluuebunny/crossref_metadata_2025 huggingface dataset:
Labile and nonlabile energy in blue grama (Bouteloua gracilis) as influenced by temperature, water stress, and fertilizer treatments
Authors: Bokhari U. G. , Dyer M. I. , Singh J. S.
Published: March 2008

Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] plants from a native shortgrass prairie were subjected to four treatments at three different temperatures in a growth chamber experiment to evaluate the dynamics of labile and nonlabile energy components in different plant organs. At high temperature regimes (24°/13° and 29.5°/18 °C day–night) blue grama plants accumulated comparatively greater amounts of labile and nonlabile energy in the three organs, viz., shoots, crowns, and roots, than at low temperature regime (13°/7 °C). The labile energy in shoots at the three temperature regimes continued to increase up to a peak value recorded at 90 days and then declined during the subsequent 30-day growth period. On the other hand, the accumulation of labile energy in roots and crowns continued till final harvest. Irrigated plus N-fertilized plants accumulated more labile and nonlabile energy in their shoots than did the irrigated plants, and the latter accumulated more than the fertilized and the control plants. The labile and nonlabile energy components in fertilized plants were at lower levels than the control plants during the 120-day growing period, resulting in net negative energy balance as compared with control plants. Higher temperature, irrigation, and irrigation plus nitrogen application decreased the nonlabile:labile ratios in the plants.
Studies on the lichen genus Evernia in North America
Authors: Bird C. D.
Published: March 2008

The four North American species of Evernia, E. divaricata (L.) Ach., E. mesomorpha Nyl., E. perfragilis Llano, and E. prunastri (L.) Ach., are discussed from the standpoint of taxonomy, distribution, and ecology. The North American distributions of E. divaricata and E. perfragilis are mapped for the first time. A puzzling lichen found on the ground in alpine areas from New Mexico north to Alberta is regarded as an ecological variant of E. divaricata.
A study of population differentiation and variation in Abies procera
Authors: Maze Jack , Parker W. H.
Published: March 2008

Abies procera Rehd. (noble fir) is a large-coned true fir of Washington and Oregon. Collections from areas north of any reported contact with its close relative, A. magnifica Murr., show population differentiation in response to the history of the site upon which the plants became established; immature trees that become established on sites denuded by clear-cut logging or mature (cone-bearing) trees that became established on sites denuded by fire are different from those that became established under mature forests. There is also a weak indication of geographic differentiation. Populations of mature trees from any one collecting site are generally more variable than immature trees from the same site. This unexpected result could be due to mature trees becoming established under many different climatic and hence selective regimes or to mature trees, which consist of more age-classes, including individuals that are made up of more generations resulting from sexual reproduction. The combination of history-related differentiation and higher variation in mature trees offers potential explanation for the high genetic variation in trees. History related population differentiation, in conjunction with the long-term fire history of forests, implies that some tree species are in fact mosaics of different populations depending on fire history and suggests that selection can cause nondirectional (= nonphyletic) changes in populations.
Effects of subminimal temperature on physiology and ultrastructure of Zea mays embryo during germination
Authors: Crèvecoeur M. , Deltour R. , Bronchart R.
Published: March 2008

The effects of a subminimal temperature on germinating Zea mays kernels have been studied at the physiological and ultrastructural levels. After 72 h of germination at 16 °C, kernels were exposed to 4 °C for intervals ranging from 4 to 25 days and then returned to 16 °C. Resumption of growth of all the embryos occurred when the cold exposure was 6 or 8 days. When periods at 4 °C were longer than 8 days, a decrease in the percentage of embryos able to grow was observed; this was proportional to the length of cold exposure. After 26 days or more at 4 °C, all the embryos died. An ultrastructural study of the primary root cells showed that modifications occur in the cytoplasm and in the nucleolus. The nucleolus became predominantly fibrillar and unusual ribonucleoproteinic granules [Formula: see text] were frequently observed in and near the nucleolus organizer region. These changes were related to a strong decrease in transcription.
Fine structure of swimming, encysting, and germinating spores of Haliphthoros milfordensis
Authors: Overton S. V. , Tharp T. P. , Bland C. E.
Published: March 2008

Electron microscope observations were made of swimming, encysting, and germinating zoospores of two strains of Haliphthorus milfordensis Vishniac isolated from gills of the white shrimp, Penaeus setiferus, and from the American lobster, Homarus americanus. Although structurally similar to zoospores of other Oomycetes, those of H. milfordensis have certain distinguishing features including: mitochondria grouped anteriorly around the nucleus, the presence of electron-dense vesicles which become transformed into unique "scalloped-fringed" vesicles, and an anterior arrangement of most cell organelles with the posterior of the zoospore being filled with numerous fibrous vesicles. During spore encystment, flagellar retraction and rounding up of the spore is accompanied by a central positioning of most cell organelles (central nucleus surrounded by concentric bands of rough endoplasmic reticulum), and ends with formation of a unique, spined, trilaminate wall. Cyst germination occurs via fracturing of the spined wall, with repeated emergence of zoospores from the spore cysts noted in addition to the more normal germ tube formation.
Scanning electron microscope study of stomatal-complex configuration in Cupressaceae
Authors: Oladele F. A.
Published: March 2008

Stomata in Cupressaceae are sunken and overtopped by subsidiary cells whose outer periclinal walls commonly protrude outwards to form the outer rim of the stomata. The rim, called the Florin ring, is either gentle or steep; it may be absent or virtually so in some genera. Subsidiary cells also possess circular, oval, or elongated papillae. The occurrence and prominence of the Florin ring and papillae are not strictly correlated with leaf shape. Taxonomic implications of the features are discussed.
Dendroglaciological evidence for Holocene glacial advances in the Todd Icefield area, northern British Columbia Coast Mountains
Authors: Jackson Scott I , Laxton Sarah C , Smith Dan J
Published: March 2008

Accelerated glacial recession and downwasting in Pacific North America is exposing land surfaces and features buried by glacial advances that, in many locations, predate the recent Little Ice Age (LIA). Dendrochronologic analyses of increment core samples from living trees (Abies lasiocarpa, Tsuga mertensiana) and samples of subfossil wood collected in the Todd Icefield area, Boundary Ranges, British Columbia Coast Mountains, provide the basis for a dendroglaciological and radiocarbon-based reconstruction of late Holocene glacier activity. Five intervals of glacier expansion were recorded by trees killed or buried by advancing glaciers: (1) an advance prior to ~3000 14C years BP; (2) an advance at ~3000 14C years BP that coincides with the regional Tiedemann advance; (3) an unattributed advance at 2300 14C years BP; (4) a two-phase advance at ~1700 and ~1450 14C years BP that corresponds with the regional First Millennium advance; (5) an advance with three phases of expansion that began prior to ~750 14C BP and is consistent with the regional early LIA interval and a two-phase interval of late LIA expansion culminating after ~240 and 100 years BP. This chronology of late Holocene glaciation matches that emerging from similar investigations in the coastal cordillera of Pacific North America and provides additional support for the regional significance of both the Tiedemann and the First Millennium advances.
Crustal structure of the Nova Scotian margin in the Laurentian Channel region
Authors: Reid I.
Published: February 2008

A seismic-refraction study on the outer Scotian Shelf of eastern Canada, carried out using large air-gun sources and ocean bottom seismograph receivers, has provided structural information on the entire crustal column. A thick (about 13 km) sedimentary sequence is characterized by significant lateral variation in this area, and a marked increase in seismic velocity around 8 km depth may delineate the synrift–postrift transition. Beneath the sediments is highly attenuated continental crust, about 11 km thick, with some evidence for a lower crustal layer of velocity around 7 km/s, which may be partly due to under-plating during rifting. Determination of the complete crustal structure, including the tentative delineation of the rift–drift transition, in a region of large crustal extension provides a useful test for models of continental rifting, and a simple uniform extension–subsidence model is found to produce an adequate fit to the interpreted structure.
Estimating abundance of spatially aggregated populations: comparing adaptive sampling with other survey designs
Authors: Mier Kathryn L , Picquelle Susan J
Published: March 2008

The main goal in estimating population abundance is to maximize its accuracy and precision. This is difficult when the survey area is large and resources are limited. We implemented a feasible adaptive sampling survey applied to an aggregated population in a marine environment and compared its performance with five classical survey designs. Specifically, larval walleye pollock (Theragra chalcogramma) in the Gulf of Alaska was used as an example of a widespread aggregated population. The six sampling designs included (i) adaptive cluster, (ii) simple random, (iii) systematic, (iv) systematic cluster, (v) stratified systematic, and (vi) unequal probability. Of the five different adaptive estimators used for the adaptive cluster design, the modified Hansen–Hurwitz performed best overall. Of the six survey designs, the stratified systematic survey provided the best overall estimator, given there was accurate prior information on which to base the strata. If no prior information was available, a systematic survey was best. A systematic survey using a single random starting point with a simple random estimator performed as well as and sometimes better than a systematic cluster survey with two starting points (clusters). The adaptive cluster survey showed no advantages when compared with these two designs and furthermore presented substantial logistical challenges.
Temporal variation in fish egg and larval production by pelagic and bottom spawners in a large Newfoundland coastal embayment
Authors: Snelgrove Paul V.R. , Bradbury Ian R , deYoung Brad , Fraser Sandra
Published: March 2008

In highly seasonal environments such as coastal Newfoundland, local production, advection, and life history may influence ichthyoplankton community structure. The spring bloom occurs in cold water that slows development of eggs from pelagic spawners and may transport propagules from optimal nearshore areas before hatch. For bottom spawners that affix eggs to the bottom, the problem is reduced because only actively swimming larval stages are pelagic. We hypothesize that larvae of pelagic spawners are limited to warmer, summer waters, whereas larvae of bottom spawners are less constrained temporally and less subject to flushing from the nearshore environment. Ichthyoplankton taxa sampled in Placentia Bay, Newfoundland, during spring–summer in 1997–1999 showed consistent seasonal peaks in egg and larval abundance. Although pelagic egg production spanned spring and summer, larval abundance peaked late in summer or early fall in the most productive areas of the bay. Larval abundance of bottom spawners peaked in spring for most taxa. Thus, pelagic eggs hatch quickly in summer, and larvae can utilize the late peak in nearshore copepod abundance. Bottom spawners can utilize spring zooplankton because temperature-dependent development does not influence egg advection. Coastal advection and temperature influence how different life history groups exploit spatial and temporal peaks in production.
Hierarchical Bayesian modelling with habitat and time covariates for estimating riverine fish population size by successive removal method
Authors: Rivot Etienne , Prévost Etienne , Cuzol Anne , Baglinière Jean-Luc , Parent Eric
Published: March 2008

We present a hierarchical Bayesian modelling (HBM) framework for estimating riverine fish population size from successive removal data via electrofishing. It is applied to the estimation of the population of Atlantic salmon (Salmo salar) juveniles in the Oir River (France). The data set consists of 10 sampling sites sampled by one or two removals over a period of 20 years (1986–2005). We develop and contrast four models to assess the effect of temporal variations and habitat type on the density of fish and the probability of capture. The Bayes factor and the deviance information criterion are used to compare these models. The most credible and parsimonious model is the one that accounts for the effects of the years and the habitat type on the density of fish. It is used to extrapolate the population size in the entire river reach. This paper illustrates that HBM successfully accommodates large but sparse data sets containing poorly informative data for some units. Its conditional structure enables it to borrow strength from data-rich to data-poor units, thus improving the estimations. Predictions of the population size of the entire river reach can be derived, while accounting for all sources of uncertainty.
Particule de spin-1 dans un potentiel d’Aharonov–Bohm
Authors: Boumali A
Published: March 2008

In this article we solved the problem of the relativistic spin-1 particle in the presence of the Aharonov–Bohm potential in two and three dimensions, while using the Duffin–Kemmer–Petiau equation. The wave functions as well as the energy spectrum, in both cases, have been obtained. The validity of the Pauli criterion in the Aharonov–Bohm effect is well discussed.
A “brief” history of spectroscopy on EBIT
Authors: Beiersdorfer P
Published: March 2008

In the autumn of 1986, the first electron beam ion trap, EBIT, was put into service as a light source for the spectroscopy of highly charged ions. On the occasion of the twentieth anniversary of EBIT, we review its early uses for spectroscopy, from the first measurements of X-rays from L-shell xenon ions in 1986 to its conversion to SuperEBIT in 1992 and rebirth as EBIT-I in 2001. Together with their sibling, EBIT-II, these machines have been used at Livermore to perform a multitude of seminal studies of the physics of highly charged ions.PACS Nos.: 01.65.+g, 32.30.–r, 32.30,Rj, 39.10.+j
Electron-impact excitation cross-section measurements at EBITs from 1986 to 2006
Authors: Chen H , Beiersdorfer P
Published: March 2008

This paper reviews the electron-impact excitation (EIE) measurements at electron beam ion trap (EBIT) facilities in the last 20~years. EIE cross sections are important atomic parameters fundamental to understanding the spectroscopic properties of ions. The properties of an EBIT make it an ideal device to measure the EIE cross section of highly charged ions. As a matter of fact, a report of EIE measurement was among the first papers published on the first EBIT ever built, EBIT-I. Since then, a wide range of measurements have been performed for K-shell and L-shell highly charged ions of Ti, V, Cr, Mn, Fe, Xe, and Ba using a combination of crystal spectrometers and solid-state X-ray detectors. In the last few years, the measurements were extended to all strong Fe L-shell lines by using a 6 × 6 pixel array microcalorimeter.PACS Nos.: 32.30.Jc, 32.30.Rj, 34.50.Fa, 32.70.Cs
High-precision spectroscopy as a test of quantum electrodynamics in light atomic systems
Authors: Drake G WF , Yan Z -C
Published: March 2008

This paper presents a review of recent progress in high-precision calculations for the ground state and low-lying excited states of helium, including the nonrelativistic energy, relativistic corrections of α2 Ry, and quantum electrodynamic (QED) corrections of lowest order α3 Ry and next-to-leading-order α4 Ry, where α is the fine-structure constant. The calculations include the terms of order α4 Ry recently obtained by Pachucki (Phys. Rev. A, 74, 062510 (2006)). Estimates of the terms of order α5 Ry, including two-loop binding corrections, are included. Comparisons with experimental ionization energies indicate reasonably good agreement for the 1s2 1S0, 1s2s 1S0, 1s2s 3S1, and 1s2p 3Pcm states, but there is a significant discrepancy for the 1s2p 1P1 state of 5.6± 3.2 MHz. An asymptotic formula for the calculation of the Bethe logarithm for Rydberg states with large angular momentum L is presented in an Appendix. PACS Nos.: 31.30.Gs, 31.30.Jv
Progress and research at the Shanghai EBIT
Authors: Hu W , Fu Y , Gong P , Yao K , Lu D , Chen W , Liu Y , Yang Y , Xiao J , Wu S , Geng Z , Huang M , Zhang X , Hutton R , Liljeby L , He M , Zou Y
Published: March 2008

In this report, a brief description of the current progress at the Shanghai EBIT project is presented. This is followed by a short discussion of the measurement of various parameters (electron beam diameter and ion density) under a number of operational conditions. A brief introduction to di-electronic recombination measurements for highly ionized xenon is given. Next, we present a preliminary measurement of the time dependence of xenon X-ray emission lines. Finally, a comparison of calculated and experimental charge-state distributions is given. This shows the influence of multi-electron capture and different distributions of the ion cloud on the charge state distribution.PACS Nos.: 41.85.–p; 34.80.Kw; 34.80Lx
The importance of EBIT data for Z-pinch plasma diagnostics
Authors: Safronova A S , Kantsyrev V L , Neill P , Safronova U I , Fedin D A , Ouart N D , Yilmaz M F , Osborne G , Shrestha I , Williamson K , Hoppe T , Harris C , Beiersdorfer P , Hansen S
Published: March 2008

The results from the last six years of X-ray spectroscopy and spectropolarimetry of high-energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell X-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus is on radiation from a specific load configuration called an “X-pinch”. In this work the study of X-pinches with tungsten wires combined with wires from other, lower Z materials is reported. Utilizing data produced with the LLNL EBIT at different energies of the electron beam the theoretical prediction of line positions and intensity of M-shell W spectra were tested and calibrated. Polarization-sensitive X-pinch experiments at the University of Nevada, Reno (UNR) provide experimental evidence for the existence of strong electron beams in Ti and Mo X-pinch plasmas and motivate the development of X-ray spectropolarimetry of Z-pinch plasmas. This diagnostic is based on the measurement of spectra recorded simultaneously by two spectrometers with different sensitivity to the linear polarization of the observed lines and compared with theoretical models of polarization-dependent spectra. Polarization-dependent K-shell spectra from Ti X-pinches are presented and compared with model calculations and with spectra generated by a quasi-Maxwellian electron beam at the LLNL EBIT-II electron beam ion trap.PACS Nos.: 32.30.Rj, 52.58.Lq, 52.70.La
Interpretation of cone penetration tests. Part II: Clay
Authors: Robertson P. K. , Campanella R. G.
Published: March 2008

This paper is the second of two parts and presents a summarized work guide for practicing engineers for interpretation of parameters for undrained conditions during the cone penetration test such as, undrained shear strength, overconsolidation ratio, and deformation characteristics of clay. The advantages, use, and interpretation of the piezometer cone are also discussed. Factors that influence the interpretations are discussed and guidelines provided. The companion paper, Part I: Sand, considers drained conditions during the test and summarizes interpretation of parameters such as relative density, friction angle, and deformation characteristics of sand. The authors' personal experiences and current recommendations are included. Keywords: static cone penetration testing, in-situ, interpretation, shear strength, modulus, stress history, pore pressures, permeability, consolidation.
Debris flows and debris torrents in the Southern Canadian Cordillera
Authors: VanDine D. F.
Published: March 2008

In Canada, debris torrents (also referred to as channelized debris flows) occur in parts of British Columbia, Alberta, and the Yukon. At least 17 deaths and an estimated $100 million of damage to bridges and property can be attributed to this natural hazard. The debris mainly comprises large boulders, rock fragments, gravel- to clay-sized material, tree and wood mulch—materials that accumulate in the mountain creeks. To be susceptible to a debris torrent, a creek must have a drainage area within a critical range, a profile that is sufficiently steep, an accumulation of debris, and some form of triggering mechanism. The most common triggering mechanism is an extreme water discharge, which may result from a very intense rainfall or a temporary damming of the creek. In western Canada, the resulting torrents involve masses of debris, typically less than 50 000 m3, that travel down creeks at speeds between 3 and 12 m/s.Several passive and active forms of mitigation can be used to reduce the impact of debris torrents on creek crossings and neighbouring residents. Passive mitigation methods include avoidance of the area, relocation of structures and facilities, land use restrictions, and some form of warning system. Active mitigation methods include remedial measures to remove or counter the causes, and various forms of designed protection. Constructing check dams near the headwaters of the creek and stabilizing the valley slopes that border the creeks are examples of remedial measures. Constructing debris barriers or clear span bridges with adequate clearance are examples of designed protection.Howe Sound, north of Vancouver, British Columbia, has had a relatively high number of debris torrents. Recently, several major studies have addressed the extent of the hazard and recommended mitigative measures for this area. Many of the examples presented in this paper are drawn from this case history. Key words: debris flows, debris torrents, slope stability, Southern Canadian Cordillera, Howe Sound, geological process, design considerations.
Synthesis of possibleo-thioquinone methide precursors
Authors: Kolmakov Kirill A , Kresge A Jerry
Published: March 2008

Investigating the synthetic accessibility of o-thioquinone methide precursors containing electron donating groups, we prepared four methyl- and methoxy-substituted 2H-benzo[b]thiete derivatives by means of flash vacuum pyrolysis of the corresponding benzooxathiinone species. Methyl- and methoxy-substituted substrates proved to be compatible with the pyrolysis protocol. The pyrolysis can be performed at considerably lower temperatures and with higher yields than in previously reported syntheses of nonsubstituted 2H-benzo[b]thiete. Under proper conditions the reaction products can be isolated in excellent yields and with 100% purity, so the troublesome purification of temperature sensitive and volatile 2H-benzo[b]thiete derivatives becomes unnecessary. The sulfur-containing compounds so obtained are efficient o-thioquinone methide precursors and possible synthones for heterocyclic chemistry.Key words: 2H-benzo[b]thietes, flash vacuum pyrolysis, methyl-substituted, methoxy-substituted, o-thioquinone methide precursors.
Photochemistry of 1,1′-bi-2-naphthol (BINOL) — ESIPT is responsible for photoracemization and photocyclization
Authors: Flegel Mitchel , Lukeman Matthew , Wan Peter
Published: March 2008

The photochemistry of 1,1′-bi-2-naphthol (BINOL, 5) has been studied in aqueous solution and found to undergo rapid deuterium incorporation at the 4 and 5 positions (in D2O-CH3CN). All data is consistent with exchange arising via a formal excited state intramolecular proton transfer (ESIPT) from the naphtholic OH to the 4 and 5 positions of the other ring to give quinine methides (QMs) 8 and 9, respectively, both of which subsequently revert to starting material. Photolysis of enantiomerically pure (+)-5 in D2O-CH3CN resulted in racemization concurrent with deuterium incorporation. This is strong evidence to indicate that photoracemization of BINOL is a direct result of ESIPT, in keeping with the invocation of planar QM intermediates. Prolonged irradiation also gave a ring-closed product that is assigned as dihydrobenzoxanthene 7, based on NMR and UV–vis data, and in analogy to known reactions of similar biaryl systems initiated by ESIPT. The formation of 7 is believed to arise via initial ESIPT from the naphtholic OH to the 7 position of the other naphthol ring generating an o-quinone methide intermediate that subsequently undergoes exclusive electrocyclic ring closure to give 7. The deuterium exchange and photocyclization reach maximum quantum efficiency at ~8 mol/L water (in CH3CN). A “water relay” mechanism for ESIPT is proposed that is consistent with the need for water in the photochemical deuterium exchange, racemization, and formation of 7. The photostability and photoracemization of other related BINOL asymmetric catalysts in water should be a concern based on the reported results herein.Key words: BINOL, ESIPT, photoprotonation, photoracemization, photocyclization, quinone methide.
A novel limonoid from the seeds of Chisocheton siamensis
Authors: Laphookhieo Surat , Maneerat Wisanu , Koysomboon Sorwaporn , Kiattansakul Rattana , Chantrapromma Kan , Syers John Keith
Published: March 2008

Analysis of an acetone/hexane (1:1) extract of the seeds of Chisocheton siamensis led to the isolation of a novel limonoid, chisosiamensin (1), along with five known limonoids, dysobinin (2), azadiradione (3), mohinin (4), epoxyazadiradione (5), and 6α-acetoxyepoxyazadiradione (6). Their structures were characterized by spectroscopic methods, including UV, IR, NMR, and MS. All isolated limonoids were reported for the first time as secondary metabolites of C. siamensis.Key words: Chisocheton siamensis, Meliaceae, chisosiamensin, limonoids.
An unexpected elimination product leads to 4-alkyl-4-deoxy-4-epi-sialic acid derivatives
Authors: Hemeon Ivan , Bennet Andrew J
Published: March 2008

A useful, unexpected β,γ-unsaturated-α-keto ester (ethyl (E)-5-acetamido-3,4,5-trideoxy-6,7:8,9-di-O- isopropylidene-D-manno-non-3-en-2-ulosonate 5) was isolated in 91% yield following ozonolysis and chromatographic purification of its enoate ester precursor ethyl 5-acetamido-2,3,4,5-tetradeoxy-6,7:8,9-di-O-isopropylidene-2-methylene- 4-nitro-D-glycero-D-galacto-nononate (6). When the 4R enoate ester (ethyl 5-acetamido-2,3,4,5-tetradeoxy-6,7:8,9-di-O- isopropylidene-2-methylene-4-nitro-D-glycero-D-talo-nononate, 7) was subjected to the same conditions, enone 5 was a minor product (18%) while the major product did not eliminate HNO2 but instead cyclized to form a five-membered ring containing a hemiaminal linkage between C-2 and the amide nitrogen on C-5 (9, 70%). Conjugate addition to enone 5 opens up the potential to generate 4-substituted sialic acid derivatives, a general route to such compounds that has not been previously reported. In a preliminary investigation of such a route, diethylzinc and dimethylzinc were added to enone 5 resulting in generation of 4-alkyl-substituted cyclic hemiaminal structures 11 and 13, which could be deprotected to form 2,7-anhydrosialic acid analogues 14 and 15. These products could then be converted to peracetylated glycals 16 and 17, the 4-methyl-substituted compound 17 being finally deprotected to give a 4-methyl- substituted analogue of the glycal of sialic acid (5-acetamido-2,6-anhydro-3,4,5-trideoxy-4-methyl-D-glycero-D-talo-non-2-enonic acid 18).Key words: conjugate addition, dialkylzinc reagent, sialic acid, ozonolysis, inhibitors.
Improved road network design models with the consideration of various link patterns and road design elements
Authors: Stückelberger Jürg , Heinimann Hans Rudolf , Chung Woodam
Published: March 2008

The success of an automatic road network layout over steep terrain mainly depends on the model design. Most previous models have used a grid representation that considers only eight adjacent cells when evaluating feasible road links. Here, we present improved models and alignment constraints mapped on a mathematical graph for better designs that are more applicable under field conditions. We have refined the link pattern by considering up to 48 neighbouring cells and have introduced 16 directional classes per grid cell. Optimization techniques, such as shortest path, minimum spanning tree, and Steiner minimum tree algorithms, are used on the graph to derive a road network that is optimal in terms of its construction costs. These improved models have been applied to different mountainous project areas. Our results show that, by considering various link patterns and alignment constraints, one can determine more appropriate and cost-effective locations for road networks, especially in steep terrain.
Inheritance of density, microfibril angle, and modulus of elasticity in juvenile wood ofPinus radiataat two locations in Australia
Authors: Baltunis Brian S. , Wu Harry X. , Powell Mike B.
Published: March 2008

A total of 1640 increment cores from 343 radiata pine ( Pinus radiata D. Don) families were sampled at two second-generation progeny trials, aged 6 and 7 years, for a detailed genetic study of juvenile wood quality traits. Density, microfibril angle (MFA), and modulus of elasticity (MOE) were determined from pith to bark using SilviScan®technology. Heritability was greatest for area-weighted density at the two sites (0.63 and 0.77, respectively), and the lowest for growth traits (<0.23). Genotype by environment interaction was low for all three wood quality traits. A positive genetic correlation between density and MOE (0.43), and a highly negative, and therefore, favourable genetic correlation between MFA and MOE (–0.92) were observed, implying that improvement of multiple juvenile wood properties is possible. The genetic correlations between whole-core wood quality traits and individual-ring measurements suggest that improvement for juvenile wood properties across the entire profile of the corewood including the innermost rings can be achieved. However, density, MFA, and MOE had unfavourable genetic correlations with diameter growth suggesting that selection for increased density and MOE, and reduced MFA in the absence of selection for growth will result in a genetic loss for growth rate.
Optimization based planning tools for routing of forwarders at harvest areas
Authors: Flisberg Patrik , Forsberg Mattias , Rönnqvist Mikael
Published: March 2008

The forwarding of logs at harvest areas once the harvesting is done is planned manually by experienced operators. To improve their efficiency and simplify the planning we have developed and tested a decision support system at a major Swedish forest company. The system is based on a combination of a geographic information system (GIS), global positioning system (GPS), and optimization routines to solve the underlying vehicle routing problem. The routes for the forwarders are found by using a repeated matching algorithm. The solution time is short, and it is possible to find routes dynamically in a real-time environment. The geographic information required is found by using a GPS together with data obtained from the bucking software in the harvesters. To show the routes and location of the forwarder, we make use of a GIS that is connected to the GPS. We report on a study with savings in the distance travelled of 8% and numerical tests on the solution methodology. We also compare the proposed solution method with some well-known routing methods.
An overview of the Fuel Characteristic Classification System — Quantifying, classifying, and creating fuelbeds for resource planningThis article is one of a selection of papers published in the Special Forum on the Fuel Characteristic Classification System.
Authors: Ottmar Roger D. , Sandberg David V. , Riccardi Cynthia L. , Prichard Susan J.
Published: March 2008

We present an overview of the Fuel Characteristic Classification System (FCCS), a tool that enables land managers, regulators, and scientists to create and catalogue fuelbeds and to classify those fuelbeds for their capacity to support fire and consume fuels. The fuelbed characteristics and fire classification from this tool will provide inputs for current and future sophisticated models for the quantification of fire behavior, fire effects, and carbon accounting and enable assessment of fuel treatment effectiveness. The system was designed from requirements provided by land managers, scientists, and policy makers gathered through six regional workshops. The FCCS contains a set of fuelbeds representing the United States, which were compiled from scientific literature, fuels photo series, fuels data sets, and expert opinion. The system enables modification and enhancement of these fuelbeds to represent a particular scale of interest. The FCCS then reports assigned and calculated fuel characteristics for each existing fuelbed stratum including the canopy, shrubs, nonwoody, woody, litter–lichen–moss, and duff. Finally, the system classifies each fuelbed by calculating fire potentials that provide an index of the intrinsic capacity of each fuelbed to support surface fire behavior, support crown fire, and provide fuels for flaming, smoldering, and residual consumption. The FCCS outputs are being used in a national wildland fire emissions inventory and in the development of fuelbed, fire hazard, and treatment effectiveness maps on several national forests. Although the FCCS was built for the United States, the conceptual framework is applicable worldwide.
Improving tree mortality models by accounting for environmental influences
Authors: Hartmann Henrik , Messier Christian , Beaudet Marilou
Published: March 2008

Tree-ring chronologies have been widely used in studies of tree mortality where variables of recent growth act as an indicator of tree physiological vigour. Comparing recent radial growth of live and dead trees thus allows estimating probabilities of tree mortality. Sampling of mature dead trees usually provides death-year distributions that may span over years or decades. Recent growth of dead trees (prior to death) is then computed during a number of periods, whereas recent growth (prior to sampling) for live trees is computed for identical periods. Because recent growth of live and dead trees is then computed for different periods, external factors such as disturbance or climate may influence growth rates and, thus, mortality probability estimations. To counteract this problem, we propose the truncating of live-growth series to obtain similar frequency distributions of the “last year of growth” for the populations of live and dead trees. In this paper, we use different growth scenarios from several tree species, from several geographic sources, and from trees with different growth patterns to evaluate the impact of truncating on predictor variables and their selection in logistic regression analysis. Also, we assess the ability of the resulting models to accurately predict the status of trees through internal and external validation. Our results suggest that the truncating of live-growth series helps decrease the influence of external factors on growth comparisons. By doing so, it reinforces the growth–vigour link of the mortality model and enhances the model’s accuracy as well as its general applicability. Hence, if model parameters are to be integrated in simulation models of greater geographical extent, truncating may be used to increase model robustness.
A stand-replacing fire history in upper montane forests of the southern Rocky Mountains
Authors: Margolis Ellis Q. , Swetnam Thomas W. , Allen Craig D.
Published: March 2008

Dendroecological techniques were applied to reconstruct stand-replacing fire history in upper montane forests in northern New Mexico and southern Colorado. Fourteen stand-replacing fires were dated to 8 unique fire years (1842–1901) using four lines of evidence at each of 12 sites within the upper Rio Grande Basin. The four lines of evidence were (i) quaking aspen ( Populus tremuloides Michx.) inner-ring dates, (ii) fire-killed conifer bark-ring dates, (iii) tree-ring width changes or other morphological indicators of injury, and (iv) fire scars. The annual precision of dating allowed the identification of synchronous stand-replacing fire years among the sites, and co-occurrence with regional surface fire events previously reconstructed from a network of fire scar collections in lower elevation pine forests across the southwestern United States. Nearly all of the synchronous stand-replacing and surface fire years coincided with severe droughts, because climate variability created regional conditions where stand-replacing fires and surface fires burned across ecosystems. Reconstructed stand-replacing fires that predate substantial Anglo-American settlement in this region provide direct evidence that stand-replacing fires were a feature of high-elevation forests before extensive and intensive land-use practices (e.g., logging, railroad, and mining) began in the late 19th century.
Effects of 12 years of repeated fertilization on the foliar nutrition and growth of young lodgepole pine in the central interior of British Columbia
Authors: Brockley R. P.
Published: March 2008

The effects of different regimes and frequencies of repeated fertilization (applied periodically and yearly) on the foliar nutrition and growth of young lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) were investigated in central British Columbia. After 12 years, tree and stand growth responses indicated modest positive effects of two applications of nitrogen (N) and boron, with relatively large incremental gains to added sulphur and other nutrients (complete). Despite large increases in effective leaf area index and foliar N concentration relative to the control and periodic treatments, yearly applications of fertilizer were relatively ineffective in stimulating growth. When combined with frequent additions of other essential nutrients, annual fertilization with 50–100 kg N/ha over 12 years (825 kg N/ha in total) produced only slightly more “extra” wood than two applications of the multinutrient, complete fertilizer (400 kg N/ha in total) (19.4 m3/ha vs. 17.2 m3/ha, respectively). The most intensive fertilization treatment (1550 kg N/ha plus other nutrients over 12 years) produced shorter trees and less stand volume increment than periodic fertilization with the complete fertilizer. Treatment-induced changes in stand dynamics and growth allocation, disrupted foliar nutrient balance, and changes in soil biota and understory vegetation community structure may have negatively affected tree growth in intensively fertilized treatment plots.
Growth and foliar nutrition of juvenile western hemlock and western redcedar plantations on low- and medium-productivity sites on northern Vancouver Island: response to fertilization and planting density
Authors: Negrave R. W. , Prescott C. E. , Barker J. E.
Published: March 2008

A factorial trial was established to examine the effects of planting density and fertilization on the growth of western redcedar ( Thuja plicata Donn ex D. Don) and western hemlock ( Tsuga heterophylla (Raf.) Sarg.) on nutrient-poor (CH) sites and nutrient-medium (HA) sites. Two levels of NPK fertilization were crossed with three levels of planting density (500, 1500, and 2500 stems/ha). Fifteen years after establishment and 10 years after the last fertilizer application, height, individual stem volume increment, stand volume, 5 year periodic annual increment (PAI), and 5 year periodic height increment were all increased by fertilization. Fertilization of CH sites increased annual stand volume increment by 753%–2552% and 122%–209% for hemlock and cedar, respectively; fertilization of HA sites increased PAI by 94%–264%. Volume growth response to fertilization was greater on HA than on CH sites. Increasing stand density reduced height growth on CH sites but not on HA sites. These results suggest that competition for nutrients can be a significant growth-limiting factor even before canopy closure occurs and that treatment of ericaceous sites may not be justified by productivity increases.
Forest-level analyses of uneven-aged hardwood forests
Authors: Yang Feng’e , Kant Shashi
Published: March 2008

The matrix growth models of maple–beech and maple stands in the uneven-aged mixed species hardwood forests in the Algonquin region of Ontario are specified as a system of simultaneous growth equations with restrictions on the sum of transition probabilities. The specified system of growth equations is estimated using the seemingly unrelated regression technique. The estimated matrix growth models are used to predict the growth dynamics of stands. Linear and nonlinear programming models are used to seek optimal management regimes and to analyze the trade-offs between financial returns and structural diversity at the forest level as well as at the stand level. The optimal harvesting schedules obtained at the forest level without ecological (residual basal area or structural diversity) constraints are identical with those obtained at the stand level; however, for higher structural diversity at the forest level, the optimal harvesting schedules based on forest-level decision making are found to be different from those based on stand-level decision making.
Genetic structure, diversity, and inbreeding of eastern white pine under different management conditions
Authors: Marquardt Paula E. , Echt Craig S. , Epperson Bryan K. , Pubanz Dan M.
Published: March 2008

Resource sustainability requires a thorough understanding of the influence of forest management programs on the conservation of genetic diversity in tree populations. To observe how differences in forest structure affect the genetic structure of eastern white pine ( Pinus strobus L.), we evaluated six eastern white pine sites across the 234 000 acre (1 acre = 0.4046856 ha) Menominee Indian Reservation in northeastern Wisconsin (45°00′N, 88°45′W). The six sites sampled for nuclear and chloroplast DNA microsatellite markers were of contrasting densities and managed by different management systems: shelterwood, pine release, plantation, and old growth. Three of the sites had natural regeneration, which was also sampled. Mean values of spatial genetic autocorrelation were positive in all mature populations and variable; the strongest spatial structuring of genes occurred in the least disturbed old-growth site (I – E(I) = 0.031). Genetic structuring at the historical old-growth site fit the isolation-by-distance model for a neighborhood size of 130 individuals. Significant inbreeding occurred in five populations, but the seedling or sapling populations as a group (f = 0.088) are significantly less inbred than the local mature populations (f = 0.197). The increase in heterozygosity between generations was attributed to harvesting having reduced the spatial genetic structure of the mature trees.
Postfire root distribution of Scots pine in relation to fire behaviour
Authors: Smirnova Evgeniya , Bergeron Yves , Brais Suzanne , Granström Anders
Published: March 2008

Fire can potentially have a large direct impact on tree roots and, thus, contribute to reduced vitality. Tree canopy status after fire should have an impact on the postfire production of fine roots, further affecting root function. We analyzed the standing crop of live and dead roots in Pinus sylvestris L. with varying degrees of crown scorch, 1 year after fire in northern Sweden. On the burned sites, total Pinus live fine-root biomass was 74% of that at the control sites, and it was only 19% of the control for roots <2 mm, indicating an 80% reduction due to fire. Root mortality was highest for high-scorch trees, but this was probably due to greater depth of burn in the organic soil for these trees and not to higher fire intensity per se. Fine-root production was also assessed by an ingrowth experiment. This showed relatively similar fine-root production in both control trees and fire-damaged trees, indicating a high allocation to root growth for the damaged trees, to make up for lost root function. Root dynamics after fire are related to a number of factors, and direct effects are determined by the depth of burn in the organic soil layer. Indirect, long-lasting effects could be due mainly to girdling of coarse roots close to tree stems and canopy loss.
The fuelbed: a key element of the Fuel Characteristic Classification SystemThis article is one of a selection of papers published in the Special Forum on the Fuel Characteristic Classification System.
Authors: Riccardi Cynthia L. , Ottmar Roger D. , Sandberg David V. , Andreu Anne , Elman Ella , Kopper Karen , Long Jennifer
Published: March 2008

Wildland fuelbed characteristics are temporally and spatially complex and can vary widely across regions. To capture this variability, we designed the Fuel Characteristic Classification System (FCCS), a national system to create fuelbeds and classify those fuelbeds for their capacity to support fire and consume fuels. This paper describes the structure of the fuelbeds internal to FCCS. Fuelbeds are considered relatively homogeneous units on the landscape, representing distinct combustion environments that determine potential fire behaviour and effects. The FCCS fuelbeds are organized into six strata: canopy, shrubs, nonwoody fuels, woody fuels, litter–lichen–moss, and ground fuels. Fuelbeds are described by several qualitative and quantitative physical and biological variables with emphasis on characteristics useful for fuels management and fire behaviour planning. The FCCS includes 216 fuelbeds that represent the major vegetation types of the United States. The FCCS fuelbeds can be used as presented or modified to create customized fuelbeds with general or site-specific data to address fire science management or research questions. This system allows resource managers to evaluate wildland fuels operations and management activities, fire hazard, and ecological and air quality impacts at small and large spatial scales. The FCCS fuelbeds represent the United States, although the system has the potential for building fuelbeds for international application.