bluuebunny/crossref_metadata_2025 huggingface dataset:
Determining Absolute Zero Using a Tuning Fork
Authors: Goldader Jeffrey D.
Published: March 2008

The Celsius and Kelvin temperature scales, we tell our students, are related. We explain that a change in temperature of 1°C corresponds to a change of 1 Kelvin and that atoms and molecules have zero kinetic energy at zero Kelvin, −273°C. In this paper, we will show how students can derive the relationship between the Celsius and Kelvin temperature scales using a simple, well-known physics experiment. By making multiple measurements of the speed of sound at different temperatures, using the classic physics experiment of determining the speed of sound with a tuning fork and variable-length tube, they can determine the temperature at which the speed of sound is zero—absolute zero.
Lava Lamp
Authors: Leif Todd R.
Published: March 2008

This past semester I brought a Lava Lite® Lamp into my classroom. Why bring such a thing into class? Many of today's students are part of the “retro” movement. They buy clothes from the '60s, they wear their hair like people did in the '60s, and they look for the ideals and themes related to living in the 1960s. Physics education reform is also examining ideas from the “retro” world of science. This was the post-Sputnik era, a time when science was done by actually doing it and not necessarily by lecturing about it. Cliff Swartz, former TPT editor, once mentioned during a presentation at a Texas AAPT meeting, “The world of physics teaching is cyclic, like a swinging pendulum. We as physics teachers jump from ‘new ideas’ back to our old ones, each generation testing what works best for them.”
Acoustical measurements of expression devices in pipe organs
Authors: Braasch Jonas
Published: March 2008

In this investigation, three different swell systems known in pipe organs, the swell box, the crescendo wheel, and the historic wind swell were measured and compared to each other. The dynamic range of the crescendo wheel was found to be most effective, and for frequencies near 2kHz the increase in sound pressure level could be up to 50dB between the softest and the loudest adjustment. The maximum dynamic range for the wind swell and the swell box were found to be 10–20dB in the same frequency range. With its step-wise crescendo procedure, the crescendo wheel simulates the type of orchestra crescendo which is reached by successively adding further musical instruments. In contrast, the swell box and the wind swell produce a crescendo effect similar to the crescendo in which individual musical instruments perform a dynamic movement. This type of crescendo requires a continuous level increase but allows a smaller dynamic range. The disappearance of the wind swell is not surprising because it offers no advantage over the swell box, while being restricted to stops with free reeds.
Selectivity of modulation interference for consonant identification in normal-hearing listeners
Authors: Apoux Frédéric , Bacon Sid P.
Published: March 2008

The present study sought to establish whether speech recognition can be disrupted by the presence of amplitude modulation (AM) at a remote spectral region, and whether that disruption depends upon the rate of AM. The goal was to determine whether this paradigm could be used to examine which modulation frequencies in the speech envelope are most important for speech recognition. Consonant identification for a band of speech located in either the low- or high-frequency region was measured in the presence of a band of noise located in the opposite frequency region. The noise was either unmodulated or amplitude modulated by a sinusoid, a band of noise with a fixed absolute bandwidth, or a band of noise with a fixed relative bandwidth. The frequency of the modulator was 4, 16, 32, or 64Hz. Small amounts of modulation interference were observed for all modulator types, irrespective of the location of the speech band. More important, the interference depended on modulation frequency, clearly supporting the existence of selectivity of modulation interference with speech stimuli. Overall, the results suggest a primary role of envelope fluctuations around 4 and 16Hz without excluding the possibility of a contribution by faster rates.
Evaluating airborne sound insulation in terms of speech intelligibility
Authors: Park H. K. , Bradley J. S. , Gover B. N.
Published: March 2008

This paper reports on an evaluation of ratings of the sound insulation of simulated walls in terms of the intelligibility of speech transmitted through the walls. Subjects listened to speech modified to simulate transmission through 20 different walls with a wide range of sound insulation ratings, with constant ambient noise. The subjects’ mean speech intelligibility scores were compared with various physical measures to test the success of the measures as sound insulation ratings. The standard Sound Transmission Class (STC) and Weighted Sound Reduction Index ratings were only moderately successful predictors of intelligibility scores, and eliminating the 8dB rule from STC led to very modest improvements. Various previously established speech intelligibility measures (e.g., Articulation Index or Speech Intelligibility Index) and measures derived from them, such as the Articulation Class, were all relatively strongly related to speech intelligibility scores. In general, measures that involved arithmetic averages or summations of decibel values over frequency bands important for speech were most strongly related to intelligibility scores. The two most accurate predictors of the intelligibility of transmitted speech were an arithmetic average transmission loss over the frequencies from 200to2.5kHz and the addition of a new spectrum weighting term to Rw that included frequencies from 400to2.5kHz.
Range-dependent waveguide scattering model calibrated for bottom reverberation in a continental shelf environment
Authors: Galinde Ameya , Donabed Ninos , Andrews Mark , Lee Sunwoong , Makris Nicholas C. , Ratilal Purnima
Published: March 2008

An analytic model is developed for scattering from random inhomogeneities in range-dependent ocean waveguides using the Rayleigh–Born approximation to Green’s theorem. The expected scattered intensity depends on statistical moments of fractional changes in compressibility and density, which scatter as monopoles and dipoles, respectively, and the coherence volume of the inhomogeneities. The model is calibrated for ocean bottom scattering using data acquired by instantaneous wide-area ocean acoustic waveguide remote sensing (OAWRS) and geophysical surveys of the ONR Geoclutter Program. The scattering strength of the seafloor on the New Jersey shelf, a typical continental shelf environment, is found to depend on wave number k, medium coherence volume Vc, and seabed depth penetration factor Fp following a 10log10(FpVck4) dependence. A computationally efficient numerical approach is developed to rapidly compute bottom reverberation over wide areas using the parabolic equation by exploiting correlation between monopole and dipole scattering terms and introducing seafloor depth penetration factors. An approach is also developed for distinguishing moving clutter from statistically stationary background reverberation by tracking temporal and spatial fluctuations in OAWRS intensity images.
Feasibility of ultrasound phase contrast for heating localization
Authors: Farny Caleb H. , Clement Greg T.
Published: March 2008

Ultrasound-based methods for temperature monitoring could greatly assist focused ultrasound visualization and treatment planning based on sound speed-induced change in phase as a function of temperature. A method is presented that uses reflex transmission integration, planar projection, and tomographic reconstruction techniques to visualize phase contrast by measuring the sound field before and after heat deposition. Results from experiments and numerical simulations employing a through-transmission setup are presented to demonstrate feasibility of using phase contrast methods for identifying temperature change. A 1.088-MHz focused transducer was used to interrogate a medium with a phase contrast feature, following measurement of the baseline reference field with a hydrophone. A thermal plume in water and a tissue phantom with multiple water columns was used in separate experiments to produce a phase contrast. The reference and phase contrast field scans were numerically backprojected and the phase difference correctly identified the position and orientation of the features. The peak temperature reconstructed from the phase shift was within 0.2°C of the measured temperature in the plume. Simulated results were in good agreement with experimental results. Finally, employment of reflex transmission imaging techniques for adopting a pulse-echo arrangement was simulated, and its future experimental application is discussed.
Vocal learning in Budgerigars (Melopsittacus undulatus): Effects of an acoustic reference on vocal matching
Authors: Manabe Kazuchika , Dooling Robert J. , Brittan-Powell Elizabeth F.
Published: March 2008

Budgerigars were trained to produce specific vocalizations (calls) using operant conditioning and food reinforcement. The bird’s call was compared to a digital representation of the call stored in a computer to determine a match. Once birds were responding at a high level of precision, we measured the effect of several manipulations upon the accuracy and the intensity of call production. Also, by differentially reinforcing other aspects of vocal behavior, budgerigars were trained to produce a call that matched another bird’s contact call and to alter the latency of their vocal response. Both the accuracy of vocal matching and the intensity level of vocal production increased significantly when the bird could hear the template immediately before each trial. Moreover, manipulating the delay between the presentation of an acoustic reference and the onset of vocal production did not significantly affect either vocal intensity or matching accuracy. Interestingly, the vocalizations learned and reinforced in these operant experiments were only occasionally used in more natural communicative situations, such as when birds called back and forth to one another in their home cages.
Demonstration of the invariance principle for active sonar
Authors: Quijano Jorge E. , Zurk Lisa M. , Rouseff Daniel
Published: March 2008

Active sonar systems can provide good target detection potential but are limited in shallow water environments by the high level of reverberation produced by the interaction between the acoustic signal and the ocean bottom. The nature of the reverberation is highly variable and depends critically on the ocean and seabed properties, which are typically poorly known. This has motivated interest in techniques that are invariant to the environment. In passive sonar, a scalar parameter termed the waveguide invariant, has been introduced to describe the slope of striations observed in lofargrams. In this work, an invariant for active sonar is introduced. This active invariant is shown to be present in the time–frequency structure observed in sonar data from the Malta Plateau, and the structure agrees with results produced from normal mode simulations. The application of this feature in active tracking algorithms is discussed.
Investigation of perceptual constancy in the temporal-envelope domain
Authors: Ardoint Marine , Lorenzi Christian , Pressnitzer Daniel , Gorea Andreï
Published: March 2008

The ability to discriminate complex temporal envelope patterns submitted to temporal compression or expansion was assessed in normal-hearing listeners. An XAB, matching-to-sample-procedure was used. X, the reference stimulus, is obtained by applying the sum of two, inharmonically related, sinusoids to a broadband noise carrier. A and B are obtained by multiplying the frequency of each modulation component of X by the same time expansion/compression factor, α (α∊[0.35–2.83]). For each trial, A or B is a time-reversed rendering of X, and the listeners’ task is to choose which of the two is matched by X. Overall, the results indicate that discrimination performance degrades for increasing amounts of time expansion/compression (i.e., when α departs from 1), regardless of the frequency spacing of modulation components and the peak-to-trough ratio of the complex envelopes. An auditory model based on envelope extraction followed by a memory-limited, template-matching process accounted for results obtained without time scaling of stimuli, but generally underestimated discrimination ability with either time expansion or compression, especially with the longer stimulus durations. This result is consistent with partial or incomplete perceptual normalization of envelope patterns.
Comparing turbulence models for flow through a rigid glottal model
Authors: Suh Jungsoo , Frankel Steven H.
Published: March 2008

Flow through a rigid model of the human vocal tract featuring a divergent glottis was numerically modeled using the Reynolds–averaged Navier–Stokes approach. A number of different turbulence models, available in a widely used commercial computational fluid dynamics code, were tested to determine their ability to capture various flow features recently observed in laboratory experiments and large eddy simulation studies. The study reveals that results from unsteady simulations employing the k–ω shear stress transport model were in much better agreement with previous measurements and predictions with regard to the ability to predict glottal jet skewing due to the Coanda effect and the intraglottal pressure distribution or related skin friction coefficient, than either steady or unsteady simulations using the Spalart–Allmaras model or any other two-equation turbulence model investigated in this study.
The mid-difference hump in forward-masked intensity discrimination
Authors: Oberfeld Daniel
Published: March 2008

Forward-masked intensity-difference limens (DLs) for pure-tone standards presented at low, medium, and high levels were obtained for a wide range of masker-standard level differences. At a standard level of 25dB SPL, the masker had a significant effect on intensity resolution, and the data showed a mid-difference hump: The DL elevation was greater at intermediate than at large masker-standard level differences. These results support the hypothesis that the effect of a forward masker on intensity resolution is modulated by the similarity between the masker and the standard. For a given masker-standard level difference, the effect of the masker on the DL was larger for a 55-dB SPL than for the 25-dB SPL standard, providing new support for a midlevel hump. To examine whether the masker-induced DL elevations are related to masker-induced loudness changes [R. P. Carlyon and H. A. Beveridge, J. Acoust. Soc. Am. 93, 2886–2895 (1993)], the effect of the masker on target loudness was measured for the same listeners. Loudness enhancement followed a mid-difference hump pattern at both the low and the intermediate target level. The correlation between loudness changes and DL elevations was significant, but several aspects of the data are incompatible with the predicted one-on-one relation between the two effects.
Inhibitory Effect of PRO 2000, a Candidate Microbicide, on Dendritic Cell-Mediated Human Immunodeficiency Virus Transfer
Authors: Teleshova Natalia , Chang Theresa , Profy Albert , Klotman Mary E.
Published: March 2008

Without an effective vaccine against human immunodeficiency virus (HIV) infection, topical microbicide development has become a priority. The sulfonated polyanion PRO 2000, a candidate topical microbicide now in phase II/III clinical trials, blocks HIV infection of cervical tissue in vitro. Dendritic cells (DC) are among the first cell types to contact HIV in the genital tract and facilitate the spread of the virus. Thus, interfering with virus-DC interactions is a desirable characteristic of topical microbicides as long as that does not interfere with the normal function of DC. PRO 2000 present during capture of the replication-defective HIVJRFLreporter virus or replication-competent HIVBaLby monocyte-derived DC (MDDC) inhibited subsequent HIV transfer to target cells. Continuous exposure to PRO 2000 during MDDC-target cell coculture effectively inhibited HIV infection of target cells. PRO 2000 inhibited HIV capture by MDDC. In addition, the compound blocked R5 and X4 HIV envelope-mediated cell-cell fusion. Interestingly, simultaneous exposure to PRO 2000 and lipopolysaccharide attenuated the cytokine production in response to stimulation, suggesting that the compound altered DC function. While efficient blocking of MDDC-mediated virus transfer and infection in the highly permissive MDDC-T-cell environment reinforces the potential value of PRO 2000 as a topical microbicide against HIV, the impact of PRO 2000 on immune cell functions warrants careful evaluation.
Synergy of a Hepatitis C Virus (HCV) NS4A Antagonist in Combination with HCV Protease and Polymerase Inhibitors
Authors: Wyles David L. , Kaihara Kelly A. , Schooley Robert T.
Published: March 2008

Rapid emergence of resistance to monotherapy with virus-specific inhibitors necessitates combination therapy. ACH-806 is a hepatitis C virus NS4A inhibitor with a novel mechanism of action and resistance pathway. This compound was synergistic with NS3 protease inhibitors and NS5B nucleoside and nonnucleoside polymerase inhibitors.
Macrophages Are Mediators of Gastritis in Acute
Helicobacter pylori
Infection in C57BL/6 Mice
Authors: Kaparakis Maria , Walduck Anna K. , Price Jason D. , Pedersen John S. , van Rooijen Nico , Pearse Martin J. , Wijburg Odilia L. C. , Strugnell Richard A.
Published: March 2008

Helicobacter pylori is
the etiological agent of human chronic gastritis, a condition seen as a precursor to the development of gastrointestinal ulcers or gastric cancer. This study utilized the murine model of chronic
H. pylori
infection to characterize the role of macrophages in the induction of specific immune responses and gastritis and in the control of the bacterial burden following
H. pylori
infection and vaccination. Drug-loaded liposomes were injected intravenously to deplete macrophages from C57BL/6 mice, and effective removal of CD11b
+
cells from the spleens and stomachs of mice was confirmed by immunofluorescence microscopy. Transient elimination of macrophages from C57BL/6 mice during the early period of infection reduced the gastric pathology induced by
H. pylori
SS1 but did not affect the bacterial load in the stomach. These data suggest that macrophages are important to the severity of gastric inflammation during
H. pylori
infection.
TheStaphyloccous aureusEap Protein Activates Expression of Proinflammatory Cytokines
Authors: Scriba Thomas J. , Sierro Sophie , Brown Eric L. , Phillips Rodney E. , Sewell Andrew K. , Massey Ruth C.
Published: March 2008

The extracellular adhesion protein (Eap) secreted by the major human pathogenStaphylococcus aureusis known to have several effects on human immunity. We have recently added to knowledge of these roles by demonstrating that Eap enhances interactions between major histocompatibility complex molecules and human leukocytes. Several studies have indicated that Eap can induce cytokine production by human peripheral blood mononuclear cells (PBMCs). To date, there has been no rigorous attempt to identify the breadth of cytokines produced by Eap stimulation or to identify the cell subsets that respond. Here, we demonstrate that Eap induces the secretion of the proinflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) by CD14+leukocytes (monocytes and macrophages) within direct ex vivo PBMC populations (note that granulocytes are also CD14+but are largely depleted from PBMC preparations). Anti-intercellular adhesion molecule 1 (CD54) antibodies inhibited this induction and implicated a role for this known Eap binding protein in cellular activation. IL-6 and TNF-α secretion by murine cells exposed to Eap was also observed. The activation of CD14+cells by Eap suggests that it could play a significant role in both septic shock and fever, two of the major pathological features ofS. aureusinfections.
Effect of nitrogen nutrition on distribution of photosynthetically incorporated 14CO2 in Lolium perenne
Authors: Barta A. L.
Published: March 2008

Ryegrass plants grown in low NO3-N, high NO3-N, or high NH4-N nutrient culture were labeled by assimilation of 14CO2 by the tops. Plants were harvested 2, 6, and 24 h after labeling and percentage, 14C incorporation was measured in ethanol-soluble, chloroform-soluble, and ethanol-insoluble fractions of leaves, stems, and roots. Low N roots accumulated the greatest and high NH4-N roots accumulated the least 14C at the end of 24 h. Low NO3-N plants had higher levels of ethanol-soluble 14C and lower chloroform-soluble and ethanol-insoluble 14C than high NO3-N plants. Analysis of the ethanol-soluble fraction revealed higher, 14C content in sugars and less in amino acids in low NO3-N plants than in high NO3-N plants. Labeling patterns in high NH4-N plants suggested incipient ammonium toxicity since 14C metabolism was retarded, yet the plants showed no visual toxicity symptoms. When using percentage conversion of label from the ethanol-soluble to ethanol-insoluble fraction as a criterion for plant metabolism, roots appeared to be more sensitive to N deficiency than were tops. This result implies that reduced root growth and (or) function (nutrient uptake) may be one of the first effects of N deficiency.
Isoenzymes in cell cultures of bush bean (Phaseolus vulgaris cv. Contender): isoenzymatic differences between stock suspension cultures derived from a single seedling
Authors: Arnison Paul G. , Boll W. G.
Published: March 2008

Electrophoretic analyses of isoenzyme patterns were performed with extracts of root, hypocotyl, and cotyledon suspension cultures derived from a single seedling. The enzymes studied included malate, glutamate, and glucose-6-phosphate dehydrogenases; peroxidase; polyphenol oxidase; esterase; acid phosphatase; and leucine amino peptidase. Peroxidase isoenzymes were also detected in the media. The isoenzymatic patterns of the three cultures were different for some enzymes, similar for others, and identical for the rest. The isoenzymatic patterns were recorded on a number of occasions over a period of 3 years and they remained relatively unchanged.
Identification of oat cultivars by means of fluorescence spectrography—a pilot study aimed at automatic identification of cultivars
Authors: Baum B. R. , Brach E. J.
Published: March 2008

The results of a pilot study aimed at automatic identification of cultivars based on the grain are presented. Using fluorescence spectrography, a band from 3000 Å to 5300 Å was found useful for discriminating six Canadian oat cultivars. It is stipulated that fluorescence spectrography reflects part of the assumed chemical pattern distinguishability between cultivars. The method is objective, reliable, and rapid. Discrimination was achieved by means of canonical analysis at this stage.
Branch architecture and its relation to shoot-tip abortion in mature Fraxinus pennsylvanica
Authors: Remphrey W. R. , Davidson C. G.
Published: March 2008

The architecture of branch complexes, 10 to 14 years old, from mature male and female green ash trees (Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern.) of two crown shapes was analyzed. Shoot length (annual increment of extension growth) declined with increasing order of branching and 47% of the shoots were less than 30 mm. Although variable, shoot length also tended to decrease along an axis. There was a consistent positive correlation between lengths and numbers of daughter shoots and lengths of parent shoots, but for a given parent length the predicted values declined proportionately with increasing order. An index of apical control comparing the lengths of terminal shoots with the longest lateral shoots revealed weaker apical control with increasing branch order in the broad, rounded crown shape class compared with the narrow shape class. Elevation angles of terminal daughter shoots were highly correlated with that of the parent shoot. When a shoot tip aborted, the terminal was replaced, but a weakening of apical control resulted in the modification of branch development and the formation of forks in certain axes. There was a reduction in the angle of divergence of lateral shoots in response to shoot-tip abortion, the terminal replacements being the most acute. Key words: crown architecture, shoot-tip abortion, green ash, Fraxinus, tree form, branching pattern.
Meiotic abnormalities during microsporogenesis and low fertility in prostrate ecotypes of Ulex species (Papilionoideae, Genisteae)
Authors: Misset M. T.
Published: March 2008

Prostrate ecotypes of the species Ulex europaeus and Ulex gallii occurring in coastal heathlands of Brittany, France frequently exhibit irregularities during meiosis that lead to partial or total male sterility. Microsporogenesis in prostrate individuals grown in an experimental garden located far from the coast appears to be normal. Their fertility is also higher, as shown by counts made on seeds and pods. Comparison of plants growing in both places suggests that the low level of fertility may be due to environmental factors like drought or salinity. On the other hand, there is no correlation between the prostrate habit and the impairment of microsporogenesis under stress. Key words: water stress, microsporogenesis, Ulex, coastal heathlands.
Ultrastructural karyology of Spongospora subterranea (Plasmodiophoromycetes)
Authors: Braselton James P.
Published: March 2008

Sporogenic (cystogenous) stages of development of Spongospora subterranea (Wallroth) Lagerheim f.sp. subterranea Tomlinson infecting potato tubers were examined with transmission electron microscopy. Volume of nuclei in transitional Plasmodia was 28.2 ± 8.3 μm3. Serial section analysis revealed 37 synaptonemal complexes, hence the haploid chromosome number was considered to be 37. Total length of synaptonemal complexes per nucleus was 74.6 ± 1.4 μm, with individual synaptonemal complexes ranging in length from 1.34 ± 0.07 μm to 3.48 ± 0.17 μm. No polycomplexes were observed in transitional nuclei. Electron-opaque thickenings of lateral elements occurred irregularly. Additional ultrastructural features of sporogenic plasmodia included end-to-end paired centrioles defining the poles of the nuclei and a host–parasite boundary of a single unit membrane. Key words: karyotype, Plasmodiophoromycetes, Spongospora, synaptonemal complex.
Induction of basidiospore germination by gluconic acid in the ectomycorrhizal fungus Tricholoma robustum
Authors: Iwase Koji
Published: March 2008

Basidiospore germination in the ectomycorrhizal fungus Tricholoma robustum and related species Tricholoma matsutake, Tricholoma caligatum, and Tricholoma ponderosum was examined. Basidiospore germination in T. robustum was induced by the presence of conspecific mycelium but not by the mycelium of related species. Germination also occurred on conditioned medium prepared by preculturing with conspecific mycelium. Gluconic acid, which is produced by T. robustum, also induced basidiospore germination in that species. After storage at 5 °C, germination of basidiospores in T. robustum was stimulated by incubation with conspecific mycelium but not with gluconic acid. These findings suggest that gluconic acid is but one of perhaps many germination-inducing substances produced by the mycelium of T. robustum. Key words: basidiospore germination, ectomycorrhizal fungi, gluconic acid, mycelial culture, Tricholoma robustum.
A morphological and biochemical analysis of embryo maturation during yellow cypress seed development
Authors: Kurz Mimi L. , Roberts Dane R. , Flinn Barry S. , Vidaver William E.
Published: March 2008

Embryo maturation in yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) seeds was studied at the morphological, anatomical, and biochemical level over the second and third seasons of seed development. Monthly cone collections were made from six open-pollinated families from two seed orchards. The average number of seeds and embryos per cone for each family was 8.8 and 4.6, respectively. Sixty to 70% of those embryos harvested from early collection dates (December 1988–March 1989) were precotyledonary (stages 1 and 2), with an average length of 0.5 mm. By April 1989 a distinct shift in the proportion of precotyledonary (stages 1 and 2) to late cotyledonary (stages 5 and 6) embryos was observed. The frequency of late cotyledonary (stages 5 and 6) embryos was 100% by August 1989 of the third growing season and averaged 2.5 mm in overall size. Moisture loss and dry weight accumulation were still progressing at the time of seed dispersal and may suggest embryo immaturity. Anatomical studies revealed protein and lipid bodies were present as early as the stage 1 embryo and became increasingly abundant during maturation. The major storage proteins isolated from protein bodies of embryo tissues had apparent molecular masses of 37, 36, 35, 34, 28, 26, and 24 kDa. Based on their solubility characteristics, the proteins were identified as buffer-soluble albumins that contained intermolecular disulfide linkages. Storage proteins were detected in early stage embryos and increased in abundance throughout maturation. Upon germination, storage proteins slowly declined to low levels by 16 and 20 days postgermination. The evidence suggests that yellow cypress embryos may be immature at the time of seed dispersal and this immaturity may contribute to the poor germination exhibited by this species.
Effects of base-cation fertilization on litter decomposition in a sugar maple forest in southern Quebec
Authors: Lukumbuzya T.K. , Fyles J.W. , Côté B.
Published: March 2008

Application of base-cation fertilizers has been shown to increase tree growth and vigour in declining sugar maple (Acersaccharum Marsh.) stands in southern Quebec but little is known about the effects of such fertilizers on litter quality or decomposition. Sugar maple foliage litters from fertilized and unfertilized plots on a base-poor site and from a naturally base-rich site were incubated in litterbags of 1- and 3-mm mesh sizes on fertilized and unfertilized plots at the base-poor site. Mass loss of unfertilized litter was slower in fertilized than in unfertilized plots, suggesting a negative effect of fertilization on the decomposer community. Faster mass loss of fertilized than unfertilized litter incubated in the same plot indicated that changes in litter quality brought about by fertilization enhanced decomposition. Mass loss of fertilized litter on fertilized plots did not differ from that of unfertilized litter on control plots, indicating that although decomposition processes are affected by fertilization the overall effect on decomposition is negligible. Mass loss was significantly, but only slightly, higher in large mesh than in small mesh bags indicating that larger soil fauna play a limited role in litter decomposition in this forest.
Jack pine budworm population behaviour in northwestern Wisconsin
Authors: Volney W. Jan A. , McCullough Deborah G.
Published: March 2008

Long-term (17–31 year) density estimates of jack pine budworm, Choristoneurapinuspinus Free. (Lepidoptera: Tortricidae), populations from 31 townships in northwestern Wisconsin were analyzed to investigate variation in population behaviour. Populations had varying combinations of cyclic components with periods of 5, 6, and 10 years. Populations that fluctuated with higher frequencies (shorter periods between outbreaks) tended to be found in locations where the habitat type was indicative of nutrient-poor and extremely dry soils. Many populations in these habitat types had high mean densities, and the coefficient of variation in density was smaller than that in other populations. Just under half (14) of the populations were regulated by statistically significant second-order density-dependent processes. Nevertheless, second-order processes were present to some extent in all populations examined. These results demonstrated that detection of density dependence and population regulation of jack pine budworm depends on the local site where studies are undertaken. Population fluctuations encountered in these populations are of the phase-forgetting quasi-cyclic kind. Studies of mechanisms that account for these cycles and cause populations to fluctuate at three different characteristic frequencies promise to be rewarding.
Effects of base cation fertilization on soil and foliage nutrient concentrations, and litter-fall and throughfall nutrient fluxes in a sugar maple forest
Authors: Fyles J.W. , Côté B. , Courchesne F. , Hendershot W.H. , Savoie S.
Published: March 2008

Application of base cation fertilizers is widely used to ameliorate decline symptoms in hardwood forests in southern Quebec, but little is known about the effects of fertilization on nutrient cycling. Control and fertilized plots in a sugar maple (Acersaccharum Marsh.) dominated stand were monitored over a 4-year period to determine the effects of fertilization on exchangeable soil base cations in soil, foliar nutrient concentrations, and fluxes of N, K, Ca, and Mg in litter fall and throughfall. Fertilization had a large, immediate effect on exchangeable K, whereas effects on Ca and Mg were delayed and restricted to the organic forest floor, presumably because of the lower solubility of the limestone-based Ca and Mg components of the fertilizer. Fertilization raised pH in the organic forest floor the second and third years after application but had no effect in the B horizon. Foliar K, Ca, and Mg were elevated in the year of fertilization, but foliar concentrations of Ca and Mg did not differ from, or were lower than, controls in following years. Litter-fall K flux was increased by fertilization, but litter-fall Ca and Mg fluxes and all through-fall base cation fluxes were unaffected. In control plots, nutrient concentrations in soil remained relatively constant throughout the study, but foliar concentrations and, in particular, litter-fall fluxes varied widely from year to year. This natural variation caused control plots to shift from a state of deficiency in N, Ca, and Mg to a nutrient-sufficient state between the first and second years of study. Fertilization effects are superimposed on a naturally variable nutrient cycling system, and controls on this variability must be understood if fertilizer response is to be accurately predicted.
Evaluating the nutrient status and fertilization response potential of planted spruce in the interior of British Columbia
Authors: Swift K.I. , Brockley R.P.
Published: March 2008

Factorial combinations of nitrogen (0, 100, and 200 kg/ha) and a "complete" fertilizer (0 and 1170 kg/ha) were applied to 10 spruce (Piceaglauca (Moench) Voss and hybrids) plantations in the central interior of British Columbia. Postfertilization patterns of foliar nutrient concentration and needle weight were used to evaluate the nutrient status and fertilization response potential of treated stands. When applied alone, N and the complete fertilizer generally had little effect on the weight of needles produced in the first year after treatment. Combined applications, however, often resulted in large responses. In 8 of the 10 installations, combined applications of N + complete fertilizer were significantly more effective than N alone in stimulating first-year needle weight. Which nutrient in the complete fertilizer is responsible for the increased needle-weight response cannot be stated conclusively. However, examination of foliar nutrient concentration data, combined with graphical analyses of relative differences in needle weight and nutrient concentration of added and nonadded nutrients, indicate that sulphur (and possibly potassium) may have a strong controlling influence on the N fertilization response potential of these stands. Systematic testing must be undertaken to verify these tentative diagnoses.
Effect of base cation addition on soil chemistry in a sugar maple forest of the Lower Laurentians, Quebec
Authors: Hendershot W.H. , Courchesne F.
Published: March 2008

Forest fertilization has been adopted as the primary means of controlling sugar maple (Acersaccharum Marsh.) dieback in southern Quebec. Following foliar analysis, treatments containing appropriate mixtures of K, Ca, Mg, and (or) P have been used on commercial sugar groves. This study was undertaken to identify the impact of base cation additions on nutrient cycling in a sugar maple stand in the Lower Laurentians, Quebec, and to quantify the amounts of added nutrients that were retained in the stand or lost by leaching. In 1988, six 40 × 40 m plots were established; three were kept as controls and the other three received a mixture of 500 kg•ha−1 of K2SO4, 250 kg•ha−1 of Ca,Mg(CO3)2 and 250 kg•ha−1 of CaCO3 applied as fine particulate matter in June 1989. Soil solutions were collected weekly during the spring and fall from October 1988 until November 1992. Soil solution chemistry indicated that there was increased biocycling of both K and Mg as a result of the treatment. The application of appropriate mixtures of base cation will improve the fertility of the soils and decrease nutrient imbalances. The amount of added material lost from the rooting zone was a small proportion of the amount added: over a 4-year period following treatment only 12.1, 9.5, and 1.4% of added Ca, Mg, and K were lost, respectively.
Wood density of western hemlock: effect of ring width
Authors: DeBell Jeffrey D. , Tappeiner II John C. , Krahmer Robert L.
Published: March 2008

Wood density of western hemlock (Tsugaheterophylla (Raf.) Sarg.) was determined by X-ray densitometry of strips from breast-height samples consisting of rings 20–24 from the pith. Ring parameters were averaged over the 5 years for each strip. Wood density was negatively correlated with radial growth rate. Average wood density dropped from 0.47 to 0.37 g/cm3 as average ring width increased from 2 to 8 mm. Wood density decreased at higher growth rates primarily because earlywood width increased while latewood width remained the same; as a result, percentage of latewood decreased. Earlywood density decreased slightly at higher growth rates, but latewood density was not significantly related to growth rate.
Growth and ecophysiological responses of black spruce seedlings to elevated CO2 under varied water and nutrient additions
Authors: Johnsen Kurt H.
Published: March 2008

not available
Effects of cultural treatments and gibberellin A4/7 on flowering of container-grown European and Japanese larch
Authors: Philipson J.J.
Published: March 2008

Gibberellin A4/A7 (GA4/7) was injected into the main stem of container-grown Larixdecidua Mill, and Larixkaempferi (Lamb.) Carr. grafts, using different quantities and times of application of GA4/7 and applying it both alone and in combination with heat, drought, girdling, or root pruning. The GA4/7 did not increase flowering, and girdling and root pruning alone were ineffective. In contrast, flowering was substantially increased when grafts were placed in a polythene house from May (beginning of long-shoot elongation) to June or early September (depending on experiments), in three separate experiments, with mean maximum temperatures of 29–30 °C. This heat treatment significantly increased both seed- and pollen-cone production, and drought treatment significantly increased seed-cone production. Treatment means of up to 143 seed cones and between 250 and 1000 pollen cones per graft, on 1.5 m tall grafts, were observed. In one experiment heat treatment in the polythene house did not increase flowering. In that experiment vegetative buds reflushed during treatment in the polythene house, which could have reduced potential flowering sites; the reflushing may have been associated with needle damage possibly caused by higher than usual temperatures, of over 40 °C.
Effects of nitrogen deficiency and recovery fertilization on ultrastructure, growth, and mineral concentrations of Scots pine needles
Authors: Palomâki V. , Holopainen T.
Published: March 2008

During the first year of a 2-year field experiment, 3-year-old Scots pine (Pinussylvestris L.) seedlings were exposed to one of three nitrogen fertilization treatments: no nitrogen, 30% optimal nitrogen, or optimal nitrogen. In the second growing period the experiment was continued as a recovery fertilization experiment. Nitrogen concentration of needles was clearly lower in seedlings of both deficiency levels than in the control seedlings by the end of the first growing season. There was a rapid development of external and ultrastructural symptoms in the first-year nitrogen-deficient seedlings. After 10 weeks of treatment, yellowing of needles, decline in growth, and reduction in ribosome and endoplasmic reticulum content at the ultrastructural level were observed compared with the controls. After 16 weeks of treatment, abnormally shaped and narrow chloroplasts were detected in the mesophyll and transfusion parenchyma tissues of current- and previous-year needles. Increased plastoglobuli number and sizes, decreased numbers of thylakoids, and decreasing electron density of chloroplast stroma followed the other changes. In the second growing season during the recovery fertilization phase, the color of the needles and the shape of the chloroplasts rapidly returned to normal, but the cytoplasmic degeneration did not totally recover. The results of the present experiment suggest that early degeneration of cytoplasmic endoplasmic reticulum and ribosomes and changes in the chloroplast shape can be regarded as characteristic symptoms of nitrogen deficiency.
Estimation of daily and seasonal whole-tree photosynthesis using Monte Carlo integration techniques
Authors: Wolf A.T. , Burk T.E. , Isebrands J.G.
Published: March 2008

Monte Carlo estimation is explored as an alternative to traditional survey sampling techniques to estimate both daily and seasonal whole-tree photosynthesis of first-year Populus clones. Several methods, known in the literature as variance-reduction techniques, are applied to the problem of estimation and compared on the basis of relative root mean squared error. Also of interest is gain in precision over the simple expansion estimator (Monte Carlo estimation in its simplest form). Variance reduction is achieved by approximating the photosynthesis curve by some known, easily integrated function. The estimators retain their unbiasedness regardless of the appropriateness of this function. The authors show how these variance reduction techniques can be used to achieve greater precision when estimating both daily and seasonal whole-tree photosynthesis. These methods may be useful alternatives to current purposive sampling methods that have the potential for bias and high error.
Genetic parameters and correlations in tests of open-pollinated black spruce families in field and retrospective nursery test environments
Authors: Mullin T.J. , Adams G.W. , Simpson J.D. , Tosh K.J. , Greenwood M.S.
Published: March 2008

Open-pollinated families represented in two series (1979 and 1980) of black spruce (Piceamariana (Mill.) B.S.P) seedling seed orchards and associated field tests were also established in retrospective greenhouse and nursery test environments. Height growth was assessed after varying numbers of growth cycles and compared with performance in the original field tests after 5, 10, and 15 years. The 1979 series consistently produced higher estimates of heritability throughout the 15 years in the field and 6 years in the retrospective nursery test. Phenotypic and genetic correlations among family means at the various field test sites were very strong for the 1979 series material, but generally much lower for the 1980 families. Correlations between performance in the field and retrospective nursery test environments were very strong and highly significant for the 1979 material, with genetic correlations in excess of 0.8. On the other hand, the 1980 material produced much lower correlations that were often not significant. In both cases, correlations with the nursery test environment appeared to peak at age 3 or 4 years. The accelerated greenhouse test environment produced very strong and highly significant correlations with field performance during all measurement intervals for the 1979 series, again with genetic correlations in excess of 0.8. The two accelerated tests of the 1980 material used differing growing regimes; one with artificially extended growing cycles, the other with compressed cycles. The extended-cycle regime produced highly significant phenotypic correlations with field performance in excess of 0.5 and genetic correlations above 0.6, while the compressed-cycle regime had weakly significant phenotypic correlations of about 0.33 and genetic correlations of about 0.4. The two test series present conflicting demonstrations of the impact of early selection. The 1979 series suggests that family selection can be done with a high degree of reliability after three or four accelerated cycles in a single nursery environment and that family rankings are reliable after only 5 years in the field tests, whereas the 1980 series suggests that longer test periods are required and that short-term nursery tests are only effective in identifying the very worst families. Reasons for this conflict and implications for operational breeding programs are discussed.
The influence of nitrogen applications on the resorption of foliar nutrients in sweetgum
Authors: Nelson L.E. , Shelton M.G. , Switzer G.L.
Published: March 2008

Resorption of foliar nutrients during senescence is one of the principal ways by which plants enhance nutrient efficiency, particularly of N and P. The objectives of this study were to determine (i) changes in foliar characteristics attributable to N applications and (ii) resorption of nutrients during foliar senescence. Rates of 0, 100, 200, and 400 kg N/ha were applied to a 9-year-old sweetgum (Liquidambarstyraciflua L.) plantation in 1981, and resorption was determined the following three growing seasons. Preceding senescence, concentrations of foliar N were doubled, P concentrations declined, and K, Ca, and Mg concentrations were relatively unaffected by N application. Losses from foliage (resorption and (or) leaching) of N, P, K, and Mg, but not Ca, were positively related to the quantity present in the presenescent foliage. Resorption of foliar N, P, K, Ca, and Mg averaged 62, 50, 48, −19, and 12%, respectively; values significantly differed among years for all nutrients. Relative resorption was unaffected by N application rates for all nutrients except K. Results indicate that resorption is an important mechanism for nutrient conservation and efficiency, and under the conditions evaluated in this study, it was influenced more by environmental conditions (i.e., weather) than by nutrient levels.