bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal landing location on flat, uniform terrain
Authors: Greulich Francis E.
Published: July 2007

A general solution procedure for the continuous demand variant of the pure location problem of Fermat–Weber is given. The solution of the Fermat–Weber problem is a specific case of the more general landing-location problem addressed in this paper. The location of a single landing site is optimized with respect to the total harvesting cost for a setting that includes the costs of roading, yarding, and hauling.
Gibberellin A4/7 enhanced flowering in Pinuscaribaea var. hondurensis
Authors: Harrison Derek L. S. , Slee Mike U.
Published: July 2007

Gibberellin A4/7 was applied to field-grown grafts of sexually mature poor and good flowering clones of Pinuscaribaea Morelet var. hondurensis. Barr. & Golf. Continuous applications of gibberellin A4/7 over a 6-week period significantly enhanced seed-cone production in poor flowering clones but had no effect on good flowering clones. Poor flowering clones also showed slight decreases in pollen-cone production with gibberellin A4/7, while clones that normally flowered well did not. Gibberellin A4/7 increased final shoot lengths in the lower (male) and upper (female) crown region of both poor and good flowering clones. A series of timed gibberellin A4/7 applications suggested that a single treatment near the onset of reproductive bud development may be used to enhance seed-cone production.
Effects of ozone and acid mist on foliar leaching from eastern white pine and sugar maple
Authors: Lovett Gary M. , Hubbell Jean G.
Published: July 2007

Upper canopy branches of mature eastern white pine (Pinusstrobus L.) and sugar maple (Acersaccharum Marsh.) were exposed in the field to ozone (25, 70, or 140 ppb) for 5 h, followed by acid mist (pH 5.0 or 3.8) for 1 h, and the exchange of major ions between the mist and the foliage was measured. The two species responded similarly to the pollutants: ozone exposure did not affect canopy exchange of any ions, but the pH 3.8 mist approximately doubled the leaching of Ca2+ and Mg2+ relative to the pH 5.0 mist. Hydrogen ions were released from the branches of both species in the pH 5.0 treatment but taken up from solution in the pH 3.8 treatment. Consideration of ionic balance in the chemical exchange indicates that organic acids were released from the branches of both species. In the white pine, it appears that these acids were deprotonated in the pH 5.0 solution, but not in the pH 3.8 solution. In the sugar maple, some acid deprotonation appears to have occurred under both pH treatments. In a related experiment, sugar maple branches that were moderately damaged by pear thrips (Taeniothripsinconsequens Uzel) did not have canopy exchange rates different from undamaged branches. Canopy exchange in the damaged branches did not respond to ozone treatment. Hydrogen ions were retained at pH 3.8 and released at pH 5.0, as in the undamaged branches. In the damaged branches, leaching of Ca2+ and Mg2+ tended to be higher at pH 3.8, although the results were not statistically significant. Overall, we conclude that short-term ozone exposures that do not produce visible damage do not affect foliar leaching, but that the acidity of rain can have a significant effect on Ca2+, Mg2+, and H+ exchange in white pine and sugar maple canopies. The net effect of those canopies on the acidity of the rain passing through them will depend on the initial acidity of the rain.
Effects of sulfometuron on hay-scented fern spore emergence
Authors: Groninger John W. , McCormick Larry H.
Published: July 2007

A greenhouse experiment was conducted to examine the effects of the herbicide sulfometuron on hay-scented fern (Dennstaedtiapunctilobula (Michx.) Moore) spore emergence. Sulfometuron was applied at rates ranging from 0.025 to 0.21 kg active ingredient per hectare to forest soil inoculated with hay-scented fern spores. Emergence based on the occurrence of prothalli was evaluated 30, 37, 44, and 52 days after inoculation. Sulfometuron at all rates completely controlled spore emergence. The data suggest that applications of sulfometuron could be effective in preventing the sexual reproduction of ferns in forest stands following soil disturbance.
The relationships of crown dieback with carbohydrate content and growth of sugar maple (Acersaccharum)
Authors: Renaud J.-P. , Mauffette Y.
Published: July 2007

Since the early 1980s, some sugar maple (Acersaccharum Marsh.) forests in northeastern North America have shown severe signs of dieback and decline. This study was designed to determine the relationships of crown dieback of sugar maple with carbohydrate content for different tissues during fall and spring and with radial growth patterns. A 100-year-old sugar maple stand located in Tingwick (Quebec, Canada) was sampled in 1987 and 1988. Growth, starch, and water-soluble carbohydrates (sucrose, glucose, and fructose) were measured in relation to crown dieback for 55 sugar maple trees. Root and stem samples were collected in April (1988), during the bud burst period, and in October (1987 and 1988), just after leaf drop. Starch was the predominant carbohydrate. In April, stem samples contained higher concentrations of glucose and fructose than in October. Conversely, roots had higher concentrations of reducing sugars in October, especially in trees, that were heavily affected by dieback. Roots of such trees also contained lower starch concentrations in October than in April. A crown deterioration index emphasized the increase in reducing-sugar concentrations found in autumn in roots of the deteriorating trees. Basal-area increment at 1.4 m was assessed from ring widths of cores collected from the trees under study. A significant growth decrease was observed for trees with 25% or more crown dieback, particularly for the last 5-year period. Thus carbohydrate concentrations and growth measurements prove to be valuable parameters in assessing tree health. Moreover, it seems that the physiological imbalances observed in declining trees may decrease the resistance of sugar maple against biotic and abiotic stresses.
Stimulation of resin flow in slash and loblolly pine by bark beetle vectored fungi
Authors: Popp Michael P. , Johnson Jon D. , Massey Thomas L.
Published: July 2007

The passive flow of resin from wounds is one mechanism that pines, Pinus spp., use in the defense against bark beetles and the pathogenic fungi they vector. Ten 18- to 20-year-old slash pine, Pinuselliottii Engelm. var. elliottii, were inoculated with spores of Ceratocystisminor (Hedge.) Hunt or Ceratocystisips (Rumb.) C. Moreau, or treated with sterile water during August 1988 to determine if resin flow is stimulated by fungal inoculation. Resin flowing from wounds was collected every 24 h for 2 days. This study was repeated in August 1989 with both slash pine and loblolly pine, Pinustaeda L., and resin was collected every 24 h for 3 days. In both species resin flow did not differ significantly among treatments during the first 24 h. However, during the second 24-h period, resin flow from the fungal-inoculated wounds was significantly greater than the flow from the sterile water treated wound. This pattern continued during the third 24-h period for slash but not loblolly pine. These results suggest that resin flow is not entirely passive and exhibits a degree of inducibility.
Organic matter and mineral distribution in an old-growth Acersaccharum forest near the northern limit of its range
Authors: Morrison I. K.
Published: July 2007

not available
Woody tissue analysis using an element ratio technique (DRIS)
Authors: Riitters K. H. , Ohmann L. F. , Grigal D. F.
Published: July 2007

The Diagnosis and Recommendation Integrated System (DRIS) was used to describe the variation of 12 elements in woody tree tissue of balsam fir (Abiesbalsamea (L.) Mill.), sugar maple (Acersaccharum Marsh.), jack pine (Pinusbanksiana Lamb.), red pine (Pinusresinosa Ait.), and aspen (Populustremuloides Michx.) across Minnesota, Wisconsin, and Michigan, United States. DRIS indices of elemental balance for the growth decades 1956–1965 and 1966–1975 were compared with standards developed from the growth decade 1976–1985. The DRIS analysis indicated that older wood of most species was relatively depleted of N, P, K, S, Fe, Cu, and Al. In at least one of the five species, however, K, S, Cu, or Al was relatively more abundant in older than in younger wood. The older wood of all species was relatively enriched in Ca, Mg, Mn, B, and Zn. Sulfur in older wood became relatively more enriched from west to east across a gradient of wet sulfate deposition; the trend was strongest for hardwood species. These results support the potential use of DRIS for monitoring stoichiometry of tissue from woody increment cores as an indicator of environmental stresses such as air pollution.
An invigoration regime for Pinusstrobus seeds
Authors: Downie Bruce , Bergsten Urban
Published: July 2007

Samples of a seed lot of eastern white pine (Pinusstrobus L.) from New Brunswick were cold stratified at moisture contents that reached five different levels from 17 to 40% of fresh weight at the end of 4 weeks. Each sample was subsequently tested for germination and mean germination time. Maximum seed germination occurred at a moisture content of about 35%. Three subsamples from another seed lot from the same area were subjected to cold stratification at a slightly suboptimal moisture content (30%) for 0, 2, or 4 weeks. These stratified seeds were subsequently invigorated at 15 °C at the same moisture content for 0, 7, 11, and 16 days. (Vigour is used in this paper to describe a seed lot's mean germination time; increased vigour signifies faster germination.) The seeds were then tested for percent germination and mean germination time. Increasing stratification and invigoration duration influenced percent germination positively, as did their interaction. Drying seeds for 24 h prior to commencing the germination test decreased germination by about 5%. Duration of stratification and invigoration were negatively and highly significantly related to mean germination time in a linear fashion, while their interactive term was nonsignificant and, therefore, not used when analyzing mean germination time. Drying the treated seeds for 24 h increased mean germination time by about 1 day. According to regression estimates, seeds germinated 0.45 ± 0.02 (mean ± SE) day faster per day of invigoration for up to 16 days treatment, while they germinated 1.44 ± 0.06 days faster per week of stratification for up to 4 weeks stratification.
Aboveground production and canopy dynamics in sugar maple and red oak trees in southwestern Wisconsin
Authors: Chapman Jonathan W. , Gower Stith T.
Published: July 2007

Aboveground net primary production, canopy allometry, growth efficiency, and sapwood volume were compared for early- to mid-successional red oak (Quercusrubra L.) and late-successional sugar maple (Acersaccharum Marsh.) co-occurring in young and mature natural stands in southwestern Wisconsin. For similar-diameter trees, shade-tolerant sugar maple supported a significantly greater (p < 0.05) stem, branch, and foliage biomass and leaf area than mid-tolerant red oak. Red oak and sugar maple had similar stem net primary production rates over a 5-year period (1984–1988), but sugar maple had a significantly greater total aboveground net primary production than similar-diameter red oak. However, red oak had a significantly greater (p < 0.0001) growth efficiency (stem net primary production per unit of leaf area) than sugar maple. The significantly greater sapwood volume, but equal stem volume, of sugar maple versus red oak suggests that annual stem maintenance respiration costs may be greater for sugar maple than for red oak. Possible causes for differences in stem net primary production and growth efficiency between early- and late-successional tree species are discussed.
Superior growth potential in trees: What is its basis, and can it be tested for at an early age? Discussion
Authors: Lanner Ronald M.
Published: July 2007

not available
Adoption of innovations by foresters: a case study of forest soils information in New Hampshire
Authors: Parmele Victoria N. , Hodges Donald G. , Luloff A.E. , Smith Jr. C. Tatersall
Published: July 2007

Identifying the factors that influence foresters to adopt management innovations is essential for developing models that accurately forecast the rate at which new technology will be adopted. Models were developed to evaluate the impact of sociodemographic characteristics, attitudes, and structural–external variables on New Hampshire foresters' decisions to adopt three distinct soil information sources. The soil information sources studied were County Soil Surveys, Important Forest Soils Groups, and Leak's Habitat Classification System. Discriminant analytic models were developed and evaluated for each information source. Information on use and other variables were collected by a mail survey with a response rate of approximately 60%. The results reveal that structural variables exerted the greatest influence on adoption decisions, while sociodemographic characteristics were the least important. College and noncollege sources of information about the innovations were the most important variables in the discriminant models. Other significant structural variables included employer, prior use of soils information, and participation in continuing education. All three models correctly classified more than 75% of the respondents, with one model classifying more than 90%. The difference in accuracy may be attributed to differences in information access among the three soils information sources.
Forest management strategies that account for short-term and long-term consequences
Authors: Ludwig Donald
Published: July 2007

This paper presents a method to calculate the long-term effects of forest management decisions for an age-structured forest. The calculation of such effects is required to assess the sustainability and indeed the rationality of forest harvesting strategies. The primary focus of this paper is the issue of "falldown", i.e., the decrease in timber available for harvesting due to lack of large old trees. The largest net discounted economic returns are obtained by rapid harvesting (mining) of old growth. However, in the longer term the consequences of a decrease in harvest volume on local communities can be devastating. How can this conflict between short-term and long-term interests be reconciled? I consider a variety of strategies that vary in their sensitivity to the effects of falldown, and I present some pilot calculations that illustrate a method to weigh the consequences of following these strategies.
Growth pattern and architectural analysis of nine important multipurpose trees in an arid region of India
Authors: Bisht R.P. , Toky O.P.
Published: July 2007

Nine multipurpose tree species (Acaciacatechu (L.f.) Willd., Acacianilotica (L.) Delile, Albizialebbeck (L.) Benth., Azadirachtaindica A. Juss., Dalbergiasissoo Roxb., Meliaazedarach L., Morusalba L., Prosopiscineraria (L.) Druce, and Ziziphusmauritiana Lam.) growing in the dry monsoonic climate of northwestern India showed a wide variation in growth pattern and shoot architecture. Six-year-old trees growing in plantation monocultures were sampled. The growing period varied from 194 days in D. sissoo to 301 days in A. nilotica. Annual shoot extension and radial growth varied from 20.6 to 111.2 cm and from 2.2 to 9.3 mm, respectively. Significant differences were found (P < 0.05) among species and among positions within the crown of each species. Dalbergiasissoo, M. azedarach, and Morusalba completed most of their growth in 120 days during the initial dry part of the growing season; these species apparently are able to utilize food reserves of the preceding year for growth. The remaining species showed a more exploitive growth strategy, having a longer period of growth which began in the dry season, but most shoot extension was completed during the rainy season that followed. Branch angle also differed significantly (P < 0.05) among crown positions of each species, except A. nilotica and D. sissoo.
Influence of feeding damage by small mammals on tree growth and wood quality in young lodgepole pine
Authors: Sullivan Thomas P. , Coates Harry , Jozsa Les A. , Diggle Paul K.
Published: July 2007

This study assessed the impact of feeding injuries by snowshoe hare (Lepusamericanus Erxleben) and red squirrel (Tamiasciurushudsonicus Erxleben) on diameter growth, height growth, and wood quality of juvenile lodgepole pine (Pinuscontorta Dougl. var latifolia Engelm.) at Prince George and in the Cariboo Region, British Columbia. In the Prince George control stand, severe girdling damage (50–99% stem circumference) suppressed diameter and height growth of small-diameter (4.1–6.0 cm) trees, but had no effect on larger stems (6.1–8.0 cm). In the spaced stand, diameter and height increments also declined significantly with degree of partial girdling, particularly in small-diameter (3.1–5.0 cm) trees. Paradoxically, diameter increment increased significantly with degree of partial girdling in both stands at the Cariboo study area. Presumably squirrels prefer to feed on vigorous stems, and the lost growth of these trees may be substantial. There was no significant difference in amount of compression wood nor total solvent and water extractives between undamaged and damaged trees. Fiber lengths in wound-associated wood were consistently 19–21% lower than in controls. Damaged trees had greater average ring width and density than undamaged trees. The average increase in relative density of damaged over undamaged trees was 0.0343. These results suggest that a severe degree of partial girdling (which likely occurs more often in small-diameter trees) may significantly affect growth of lodgepole pine, particularly small (<5.0 cm DBH) trees.
Effects of selected forest management practices on environmental parameters related to successional development on the Tanana River floodplain, interior Alaska
Authors: Yarie John
Published: July 2007

Two mature floodplain white spruce (Piceaglauca (Moench) Voss) ecosystems (stage VIII) located on islands in the Tanana River, approximately 20 km southwest of Fairbanks, Alaska, were clear-cut during the winter of 1985–1986 to quantify the effects of clear-cutting on selected environmental characteristics. Clearings in earlier successional stages (poplar–alder (Populus–Alnus), stage V; and open willow (Salix), stage III) were used to contrast the environmental parameters with the earlier stages found in the primary successional sequence. After clear-cutting, total radiation at the soil surface increased to early successional stage III levels. Potential evaporation from the soil surface increased 5-fold as a result of clearing in the stage VIII sites and was substantially greater than that found in the stage III sites by other researchers. Clearing had relatively little effect on air temperature. The concentration of P and K was significantly lower in the forest floor of both clearcuts, and the concentration of C was significantly higher at VIII-A-T (stage VIII–site A–treated (cleared) plot) when compared with the control stands. There was a decrease in total forest floor biomass at both clear-cut plots. Organic matter, total N, available NH4 and P, and extractable Mg and K all decreased after cutting, whereas pH increased. Decomposition of spruce foliage on the forest floor surface was slower in the clearcuts. Nitrogen immobilization occurred during the first 2 years of decomposition. During the third year it appeared that some mineralization was beginning to occur but the levels were very low, averaging only 3 mg N per bag in the clear-cut areas. Plant growth analysis indicated that growth was limited by high mineral soil salt content in the early successional stages (III) and that this limitation was species specific. Balsam poplar (Populusbalsamifera L.) appears to be more tolerant of the high cation content of the stage III sites compared with trembling aspen (Populustremuloides Michx.). By the time successional development has progressed to stage V, the soil has been sufficiently augmented by the inclusion of organic matter from the developing vegetation and the fixation of N by alder to result in higher seedling growth rates in the cleared areas.
Soil nutrient availability and relationships with aboveground biomass production on postharvested upland white spruce sites in interior Alaska
Authors: Paré David , Cleve Keith Van
Published: July 2007

Soil nutrient availability was assessed on unharvested white spruce (Piceaglauca (Moench) Voss) sites, on a recently harvested site and on 14-year-old postharvested sites stratified into four different regeneration types defined by surface soil conditions and colonizing species. These values were compared with field aboveground biomass production that had been estimated in a previous study and with biomass production of bioassay seedlings. All sites were upland and south facing. On this range of sites, laboratory net N mineralization was the soil characteristic that was the most strongly associated with plant growth in the field as well as in the greenhouse bioassay. The significance of this relationship was mainly caused by the presence of sites regenerating to aspen (Populustremuloides Michx.) which showed high plant biomass production and high soil N availability. Total soil N content, cumulative field soil temperature and soil moisture content were poorly related to N mineralization estimates and to plant biomass production. Soil temperature had an effect on N mineralization and plant growth only when sites where the forest floor had been scraped during the harvesting operations, were included in the computations. Despite a higher soil temperature, these sites showed decreased N mineralization rates and decreased plant biomass production. These results suggest that on south facing postharvested white spruce sites (i) soil temperature does not show enough variability to be an important factor controlling nutrient availability and plant growth unless the soil is severely disturbed, (ii) the rate of N mineralization is controlled by a small pool of rapidly cycling N which is poorly related to forest floor total N concentrations, and (iii) N availability and vegetation production vary with regeneration type.
Defoliation of tamarack by outbreak populations of larch sawfly in subarctic Quebec: measuring the impact on tree growth
Authors: Tailleux Isabelle , Cloutier Conrad
Published: July 2007

In conjunction with other major perturbations, outbreaks of specialist insect defoliators could play a key role in the long-term evolution of northern forest communities. Sawfly oviposition marks up to 20 years old in shoots of tamarack, Larixlaricina (Du Roi) K. Koch, provide a direct record of a large-scale epidemic cycle of the larch sawfly, Pristiphoraerichsonii (Htg.), during the 1980s in the Grande Rivière de la Baleine region, northern Quebec. Because no significant tree mortality was noted in the years following peak defoliator populations in 1985–1986, a study was undertaken to determine whether insect population changes during the outbreak period were correlated with growth changes under various climatic and soil conditions in three coastal sites and one continental sampling site. The fluctuations with time in the density of oviposition marks on trees indicated that the epidemic cycle was synchronous at all sites. However, the defoliator's density was significantly higher at the inland site, located 150 km from Hudson Bay, than at the coastal sites, where climatic conditions may be less favorable to insect activity and survival. No significant effects on tree growth were detected at the coastal sites, whereas larch from the inland site recorded a significant reduction in radial growth in 1984, the 1st year of outbreak conditions. Larch from this site also showed significant effects on foliage development after 4 years of defoliation (1988), when a virtual stop on elongative growth became apparent. Larch trees reproduced actively during the outbreak, with peak reproductive effort in 1984 and 1987 correlating with lows in elongative growth. Delayed or minimal effects of this outbreak characterized by the presence of hundreds of sawfly colonies per tree and defoliation levels comparable to those observed in the boreal forest during similar outbreaks indicate that subarctic larch may be highly tolerant to prolonged defoliation by the larch sawfly.
Simulated optimal structure of a photosynthetic system: implication for the breeding of forest crop ideotype
Authors: Wu Rong-Ling
Published: July 2007

A single leaf and canopy are two different levels of a photosynthetic system which have the function of carbon fixation and energy balance for plant and crop processes. A mechanistic model was derived to understand the photosynthetically based optimal structure for the maximization of whole-system nitrogen-use efficiency. The model is based upon the use of a nonrectangular hyperbola for leaf photosynthetic response to irradiance, the linear relationship of photosynthetic capacity with nitrogen content, and the Monsi–Saeki theory for the light-intercepting characteristics of the system. The whole-system carbon gain is maximized by partitioning of leaf nitrogen content (therefore photosynthetic capacity and other related physiological parameters) in terms of negatively exponential decrease with cumulative leaf area index, which has the same extinction rate with irradiance within the system. The biomass production of the photosynthetically based optimal structure (ideotype) and its relative advantage over uniform structure increase with increasing irradiance, nitrogen availability, and leaf area index. Such properties of ideotypes associated with leaf biology and geometry are discussed, as well as their application to short-rotation intensive culture in forest crops.
Genetic variation in red alder (Alnusrubra) in relation to native climate and geography
Authors: Ager A. A. , Heilman P. E. , Stettler R. F.
Published: July 2007

Genetic variation was examined within and among populations of red alder (Alnusrubra Bong.) from elevational gradients in four river drainages of the Pacific Northwest. Wind-pollinated progenies of 120 trees were grown for 3 years in a common garden environment and measured for growth and shoot phenology. Variation in top weight, bud flush, and leaf abscission was analyzed in relation to native climate and elevation and compared with sympatric species. Strong geographic patterns of variation were observed for all measured traits, apparently reflecting adaptations to highly variable climates within the region studied. Growth traits were correlated with temperature amplitude and length of growing season. Growth rhythm in bud flushing and growth cessation was related to two important environmental cues, spring thermal sums and fall frost dates. Overall levels of variation in red alder appeared to be similar to several sympatric conifers, although variation within populations of red alder was lower. The latter finding may be due to the demography of the riparian populations sampled, or perhaps a characteristic of the species and its colonizing life history.
Throughfall nitrogen in a white spruce forest in southwest Alberta, Canada
Authors: Blew R.D. , Iredale D.R. , Parkinson D.
Published: July 2007

Rates of transfer of nitrogen in throughfall were measured in a Piceaglauca (Moench) Voss forest in southwest Alberta, Canada. Total annual flux of N in throughfall was estimated to be 6.8 kg•ha−1•year−1. The highest rates of N deposition in throughfall occurred during the spring. The pattern of seasonal variation of N in throughfall suggested that different processes of N accumulation in and loss from the canopy may have been operating at different times of the year. Annual leaching of N from the canopy was estimated to be 4.09 kg•ha−1•year−1 and represented 24% of the total amount of N returned to the forest floor (leachates plus litter fall).
Variations in cryotolerance of embryogenic Piceaabies cell lines and the association to genetic, morphological, and physiological factors
Authors: Nørgaard Jens Viktor , Duran Valerie , Johnsen Øystein , Krogstrup Peter , Baldursson Snorri , Arnold Sara Von
Published: July 2007

Two sets, containing 9 and 72 embryogenic cell lines of Piceaabies (L.) Karst., were tested for cryotolerance using a standard two-step cryopreservation protocol. Eight and 69 cell lines, respectively, survived freezing in all or some of the trials. A strong effect of cell line on regrowth after freezing was demonstrated in both sets. Culture morphology and maturation competence of the nine cell lines was unaffected by freezing and were not correlated to cryotolerance. In the 72 cell lines originating from seeds of five full-sib families, selected from a progeny test for their widely different autumn frost hardiness, a family effect on cryotolerance was observed. This effect was not related to physiological characters (ability to form embryogenic cultures and mature somatic embryos, autumn frost hardiness)
Canopy transmittance models for estimating forest leaf area index
Authors: Nel Elizabeth M. , Wessman Carol A.
Published: July 2007

Leaf area index was estimated in old-growth and young post-fire coniferous forests in northwestern Colorado. A line quantum sensor was used to measure canopy transmittance at different solar zenith angles. Leaf area indices were estimated from canopy transmittance data according to three different models and were subsequently compared with leaf area indices derived from existing allometric equations. Of the three canopy transmittance methods evaluated, a Beer–Lambert model adjusted for diffuse light and solar zenith angle was in closest agreement with allometric leaf area index estimates (11.5% average difference), followed closely by the Beer–Lambert model (14.4% average difference). Leaf area index predicted by a one-dimensional inversion model did not agree well with allometric estimates (30.6% average difference). Differences in methods of data processing were found to have significant effects on final results. Subtraction of diffuse photosynthetically active radiation increased the leaf area indices. Calculation of leaf area index at each sampled point and determination of a final mean leaf area index approximated the allometrically derived values more closely than did derivation of leaf area index only once from an averaged gap-fraction value. Leaf area index estimates varied with sun angle.
Voltage Dependence of Cardiac Excitation–Contraction Coupling
Authors: Altamirano Julio , Bers Donald M.
Published: July 2007

Excitation–contraction coupling in cardiac myocytes occurs by Ca
2+
-induced Ca
2+
release, where L-type Ca
2+
current evokes a larger sarcoplasmic reticulum (SR) Ca
2+
release. The Ca
2+
-induced Ca
2+
release amplification factor or gain (SR Ca
2+
release/
I
Ca
) is usually assessed by the
V
m
dependence of current and Ca
2+
transients. Gain rises at negative
V
m
, as does single channel
I
Ca
(
i
Ca
), which has led to the suggestion that the increases of
i
Ca
amplitude enhances gain at more negative
V
m
. However,
I
Ca
=NP
o
×
i
Ca
(where NP
o
is the number of open channels), and NP
o
and
i
Ca
both depend on
V
m
. To assess how
i
Ca
and NP
o
separately influence Ca
2+
-induced Ca
2+
release, we measured
I
Ca
and junctional SR Ca
2+
release in voltage-clamped rat ventricular myocytes using “Ca
2+
spikes” (confocal microscopy). To vary
i
Ca
alone, we changed [Ca
2+
]
o
rapidly at constant test
V
m
(0 mV) or abruptly repolarized from +120 mV to different
V
m
(at constant [Ca
2+
]
o
). To vary NP
o
alone, we altered Ca
2+
channel availability by varying holding
V
m
(at constant test
V
m
). Reducing either
i
Ca
or NP
o
alone increased excitation–contraction coupling gain. Thus, increasing
i
Ca
does not increase gain at progressively negative test
V
m
. Such enhanced gain depends on lower NP
o
and reduced redundant Ca
2+
channel openings (per junction) and a consequently smaller denominator in the gain equation. Furthermore, modest
i
Ca
(at
V
m
=0 mV) may still effectively trigger SR Ca
2+
release, whereas at positive
V
m
(and smaller
i
Ca
), high and well-synchronized channel openings are required for efficient excitation–contraction coupling. At very positive
V
m
, reduced
i
Ca
must explain reduced SR Ca
2+
release.
Ezetimibe is effective when added to maximally tolerated lipid lowering therapy in patients with HIV
Authors: Bennett Matthew T. , Johns Kevin W. , Bondy Gregory P.
Published: July 2007

To determine the efficacy and safety of adding ezetimibe to maximally tolerated lipid lowering therapy in patients with HIV dyslipidemia.

Retrospective analysis of lipid parameters was conducted for 33 patients with HIV who had been prescribed ezetimibe 10 mg per day.

Mean total cholesterol was reduced 21% (p < 0.001). Mean LDL was reduced 35% (p < 0.001). Mean HDL increased 8% (p = 0.038). Mean triglyceride was reduced 34% (p = 0.006). Mean Apolipoprotein B100 was reduced 33% (p = 0.043). No adverse events occurred.

Ezetimibe appears safe and effective in patients with HIV when added to maximally tolerated doses of lipid lowering therapy.
Differential heating and cooling rates in bigeye tuna (Thunnus obesus Lowe): a model of non-steady state heat exchange
Authors: Malte Hans , Larsen Christina , Musyl Michael , Brill Richard
Published: July 2007

We analyzed water temperature, visceral cavity temperature and depth data from archival tags retrieved from bigeye tuna (Thunnus obesus) at liberty in the central Pacific for up to 57 days using a mathematical model of heat exchange. Our model took into account the transfer of heat between the portions of the myotomes comprising red muscle fibers adjacent to the spinal column and served by vascular counter current heat exchanges (henceforth referred to as `red muscle') and the water, as well as between the red muscle and the temperature sensor of the archival tags in the visceral cavity. Our model successfully predicted the recorded visceral cavity temperatures during vertical excursions provided that the rate constants for heat transfer between the ambient water and the red muscle during cooling (klow)and those during heating (khigh) were very dissimilar. Least-squares fitting of klow and khigh for the entire period that the fish were at liberty yielded values generally in the ranges 0.02–0.04 min–1and 0.2–0.6 min–1 (respectively), with an average ratio khigh/klow of ≈12. Our results confirmed those from previous studies showing that bigeye tuna have extensive physiological thermoregulatory abilities probably exerted through changes of blood flow patterns that controlled the efficiency of vascular countercurrent heat exchanges. There was a small but significant negative correlation between klow and size, whereas there was no correlation between khigh and size. The maximum swimming speeds during vertical excursions (calculated from the pressure data) occurred midway during ascents and averaged ≈2 FL s–1 (where FL=fork length), although speeds as high ≈4–7 FLs–1 were also noted.
Disruptive coloration elicited on controlled natural substrates in cuttlefish,Sepia officinalis
Authors: Mäthger Lydia M. , Chiao Chuan-Chin , Barbosa Alexandra , Buresch Kendra C. , Kaye Sarrah , Hanlon Roger T.
Published: July 2007

Cephalopods are known for their ability to change camouflage body patterns in response to changes in the visual background. Recent research has used artificial substrates such as checkerboards to investigate some specific visual cues that elicit the various camouflaged patterns in cuttlefish. In this study, we took information from experiments on artificial substrates and assembled a natural rock substrate (fixed with glue) with those features that are thought to elicit disruptive coloration in cuttlefish. The central hypothesis is that light rocks of appropriate size, substrate contrast and edge characteristics will elicit disruptive camouflage patterns in cuttlefish. By adding graded light sand in successively greater quantities to this glued rock substrate, we predicted that disruptive camouflage patterns would be replaced by progressively more uniform patterns as the visual features of rock size, contrast and edges were altered by the addition of sand. By grading the degree of disruptiveness in the animals' body patterns, we found that the results support this prediction, and that there is a strong correlation between fine details of the visual background properties and the resultant body pattern shown by the cuttlefish. Specifically, disruptive coloration was elicited (1) when one or a few light rocks of approximately the size of the animal's White square skin component were in the surrounding substrate (dark rocks alone did not elicit disruptive coloration), (2) there was moderate-to-high contrast between the light rocks and their immediate surrounds, and (3) the rock edges were well defined. Taken together, the present study provides direct evidence of several key visual features that evoke disruptive skin coloration on natural backgrounds.
Analbuminemia Produced by a Novel Splicing Mutation
Authors: Dolcini Lorenzo , Caridi Gianluca , Dagnino Monica , Sala Alberto , Gökçe Selim , Sökücü Semra , Campagnoli Monica , Galliano Monica , Minchiotti Lorenzo
Published: July 2007

Analbuminemia is a rare autosomal recessive disorder manifested by the absence or severe reduction of circulating human serum albumin in homozygous or compound heterozygous individuals. It is an allelic heterogeneous defect, caused by a variety of mutations within the albumin gene. The analbuminemic condition was diagnosed in a Turkish female infant on the basis of low albumin concentration (∼9.0 g/L). The albumin gene was screened by single-strand conformation polymorphism and heteroduplex analysis and submitted to direct sequencing. The proband was found to be homozygous for a T→C transition at nucleotide 13381, the 2nd base of intron 11. The effect of this previously unreported mutation, which inactivates the strongly conserved GT dinucleotide at the 5′ splice site consensus sequence of intron 11, was evaluated by examining the cDNA obtained by reverse transcription-PCR from the albumin mRNA extracted from the proband leukocytes. This analysis revealed that the mutation, named Bartin for the geographical origin of the patient’s family, results in the skipping of exon 11. The subsequent frameshift within exon 12 originates a premature stop codon located 5 codons downstream at position 411. The predicted translation product would consist of 410 amino acids. This novel extensive cDNA alteration is responsible for the analbuminemic trait.
The influence of social factors and implicit racial bias on a generalized own‐race effect
Authors: Walker Pamela M. , Hewstone Miles
Published: July 2007

The current study sought to determine whether the experimentally reported ‘own‐race effect’ is other‐race specific, or whether it is a generalized effect. The perceptual processing of own‐ versus two groups of other‐race faces was therefore explored in White and South Asian individuals. Participants completed a computer‐based discrimination task of White, South Asian and Black face‐morphs. Results showed a generalized own‐race effect for White and South Asian participants discriminating own‐ versus other‐race (White/South Asian and Black) faces, such that individuals demonstrated a perceptual discrimination advantage for own‐ versus other‐race faces in general. These findings were linked to implicit racial bias and other‐race individuating experience, demonstrating that social variables play an important role in the magnitude of the own‐race effect. Copyright © 2007 John Wiley & Sons, Ltd.
Katalytische Flüssigphasenumwandlung oxygenierter Kohlenwasserstoffe aus Biomasse zu Treibstoffen und Rohstoffen für die Chemiewirtschaft
Authors: Chheda Juben N. , Huber George W. , Dumesic James A.
Published: July 2007

Für die moderne Industriegesellschaft hat Biomasse ein enormes Potenzial als nachhaltiger Energieträger und Quelle organischen Kohlenstoffs. Ziel dieses Aufsatzes ist es, eine Übersicht über katalytische Reaktionen in der flüssigen Phase zu geben, in denen Sauerstoff‐haltige Rohstoffe aus Biomasse (vor allem Zucker und Zuckeralkohole) in wertvollere Chemikalien und Treibstoffe umgewandelt werden, wobei ein besonderer Schwerpunkt auf solchen katalytischen Transformationen liegt, die aus einem Verständnis der fundamentalen Reaktionsmechanismen abgeleitet wurden. Die Schlüsselreaktionen bei der chemischen Umwandlung von Biomasse sind Hydrolyse, Dehydratisierung, Isomerisierung, Aldolkondensation, Reformierung, Hydrierung und Oxidation. Ferner wird diskutiert, wie aus grundlegenden chemischen und katalytischen Konzepten Strategien für die Steuerung von Reaktionsverläufen und Prozessbedingungen erarbeitet werden können. Als Beispiele dienen dabei die Herstellung von H2/CO2‐ oder H2/CO‐Gasmischungen durch Reformierung in der wässrigen Phase, die Produktion von Furanen durch selektive Dehydratisierung von Kohlenhydraten und die Erzeugung flüssiger Alkane durch Kombination der Aldolkondensation mit Dehydratisierungs‐ und Hydrierungsprozessen.
Liquid‐Phase Catalytic Processing of Biomass‐Derived Oxygenated Hydrocarbons to Fuels and Chemicals
Authors: Chheda Juben N. , Huber George W. , Dumesic James A.
Published: July 2007

Biomass has the potential to serve as a sustainable source of energy and organic carbon for our industrialized society. The focus of this Review is to present an overview of chemical catalytic transformations of biomass‐derived oxygenated feedstocks (primarily sugars and sugar‐alcohols) in the liquid phase to value‐added chemicals and fuels, with specific examples emphasizing the development of catalytic processes based on an understanding of the fundamental reaction chemistry. The key reactions involved in the processing of biomass are hydrolysis, dehydration, isomerization, aldol condensation, reforming, hydrogenation, and oxidation. Further, it is discussed how ideas based on fundamental chemical and catalytic concepts lead to strategies for the control of reaction pathways and process conditions to produce H2/CO2 or H2/CO gas mixtures by aqueous‐phase reforming, to produce furan compounds by selective dehydration of carbohydrates, and to produce liquid alkanes by the combination of aldol condensation and dehydration/hydrogenation processes.
Influence of the γ‐ray dose on the electrical properties of toluene diisocyanate mixed with naturally dehydrated caster oil fatty acids
Authors: Akraiam F. A. , Elaydy A. B. , Abed El‐Latif A. A.
Published: July 2007

Measurements of the alternating‐current conductivity and direct‐current conductivity before and after irradiation were studied for matrices composed of toluene diisocyanate mixed in four different ratios with dehydrated caster oil fatty acids. Different irradiation doses were investigated for all the samples. The alternating‐current conductivity in the frequency range of 500–10000 Hz was found to obey the very well‐known law σac(ω,T) = AωS, where σac(ω,T) is the alternating‐current conductivity at angular frequency ω and temperature T and S is an exponent. The exponent decreased with increasing temperature for all compositions. A strong temperature dependence of the alternating‐current conductivity and the exponent in the entire ranges of the temperatures and frequencies was reasonably interpreted with the correlated barrier‐hopping model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and characterization of calcium carbonate/low‐density‐polyethylene nanocomposites
Authors: Wang Wen‐Yi , Zeng Xiao‐Fei , Wang Guo‐Quan , Chen Jian‐Feng
Published: July 2007

Calcium carbonate/low‐density‐polyethylene (LDPE) nanocomposites have been prepared by melting blend with twin‐screw extruder. The mechanical properties of composites and the dispersion of the nanoparticles were studied. The reinforcement mechanism was discussed. The results show that not only the tensile property but also the flexural modulus of the system have been evidently increased by the addition of calcium carbonate. The calcium carbonate particles have been dispersed in the matrix in the nanometer scale. The reinforcement mechanism of the calcium carbonate lies on that the calcium carbonate particles, acting as hetero‐nuclei, can induce higher crystallinity at the matrix‐particle interface compared to regions away from the interface. Consequently, in the process of the tensile test, the nanocomposites have better tensile yield strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Miscibility and intermolecular hydrogen‐bonding interactions in poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/poly(4‐vinyl phenol) binary blends
Authors: Alata Hexig , Zhu Bo , Inoue Yoshio
Published: July 2007

The miscibility and hydrogen bonding interaction in the poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)/poly(4‐vinyl phenol) [P(3HB‐co‐3HH)/PVPh] binary blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The DSC results indicate that P(3HB‐co‐3HH) with 20 mol % 3HH unit content is fully miscible with PVPh, and FTIR studies reveal the existence of hydrogen bonding interaction between the carbonyl groups of P(3HB‐co‐3HH) and the hydroxyl groups of PVPh. The effect of blending of PVPh on the mechanical properties of P(3HB‐co‐3HH) were studied by tensile testing. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Poly(1,3‐propylene glycol‐hexanedioic acid) grafted hydroxyl multiwall carbon nanotubes
Authors: Meng Qing‐Jie , Zhang Xing‐Xiang , Bai Shi‐He
Published: July 2007

Poly(1,3‐propylene glycol‐hexanedioic acid) grafted hydroxyl multiwall carbon nanotube (PHHCNT) was fabricated in the presence of butyl titanate using 1,3‐propylene glycol, hexanedioic acid, and hydroxyl multiwall carbon nanotubes as reactants. The hydroxyl groups at carbon nanotubes reacted with hexanedioic acid and a small amount of carboxyl groups reacted with 1,3‐propylene glycol, resulting in the PGHA grafted on the carbon nanotubes. The carbon nanotubes surrounded by the PGHA chains with an average thickness of ∼ 2 nm. The polycondensation reactions can be controlled by the feed contents of HCNTs and the catalyst concentration in the reactants. The content of HCNTs in PHHCNT rises with an increase of the feed contents of HCNTs. In addition, the content of HCNTs in PHHCNT is higher than the feed contents of HCNTs in the reactants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Swelling and antibacterial properties for the superabsorbent hydrogels containing silver nanoparticles
Authors: Lee Wen‐Fu , Huang Yu‐Chen
Published: July 2007

A series of antibacterial superabsorbents containing silver nanoparticles based on sodium acrylate (SA), 1‐vinyl‐2‐pyrrolidone‐silver ion complex (VP‐Ag+) and N, N′‐ methylene‐bisacrylamide (NMBA) were prepared by inverse suspension polymerization. The ascorbic acid (vitamin C) was used as reductant to reduce silver ion complex in the gels through in situ reduction method. The influence of the concentration of VP‐Ag+ complex in the superabsorbents on the water absorbency, swelling behavior, and antibacterial effect of Candida albicans was investigated. Results showed that the water absorbency for sodium acrylate and VP copolymeric gel (SV gel) in deionized water was 1016 g H2O/g gel, but the water absorbency for SV‐Ag series gel decreased when the silver nanoparticle was added. Results also showed that the antibacterial effect of the superabsorbents increased with an increase of the silver concentration (1 ∼ 10 ppm). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007