Showing papers by "North Carolina State University published in 1988"
TL;DR: The range of inhibitory activity by bacteriocins of lactic acid bacteria can be either narrow, inhibiting only those strains that are closely related to the producer organism, or wide, inhibited a diverse group of Gram-positive microorganisms as mentioned in this paper.
1,754 citations
TL;DR: In this article, the atomic bonding configurations of carbon bonding in diamond and diamond-like thin films are explored using Raman scattering, and the general aspects of Raman scatter from composites are presented.
Abstract: The atomic bonding configurations of carbon bonding in diamond and diamondlike thin films are explored using Raman scattering. The general aspects of Raman scattering from composites are presented. Effects are discussed due to crystalline or amorphous structures, large versus microcrystalline domains, and strong optical absorption and transparent regions. The Raman scattering from diamondlike films shows several features which are attributed to microcrystalline graphitelike structures which all originate from the same region in the sample. In contrast, the spectra of diamond films show features attributed to different components of a composite film. Components identified are crystalline diamond, and disordered and microcrystalline graphitic structures. The presence of precursor microcrystalline or amorphous diamond structures is also suggested.
641 citations
TL;DR: In this paper, a survey was conducted in 20 rural communities as part of the 1985 Colorado Rural Recreation Development Project administered by the University of Colorado-Boulder to determine whether residents' perceptions of community life satisfaction vary with the levels of tourism development in theircommunity.
Abstract: Thepurpose of this study was to determine whether residents' perceptions of community life satisfaction vary with the levels of tourism development in theircommunity. Thestudy was conducted in 20 rural communities as part of the 1985 Colorado Rural Recreation Development Project administered by the University of Colorado-Boulder. A comprehen sive questionnaire investigating residents'perceptions of the importance of and their satis faction with seven dimensions of community life was distributed to one adult member of randomly selected households in each community. The seven dimensions ofcommunity life were public services, economics, environment, medical services, citizen involvement, for mal education, and recreation services. In order to determine which dimensions were most sensitive to changes in the level of tourism development, canonical analysis was conducted using tourism development ratings and community population as the set of independent variables and the seven importance and seven satisfaction...
568 citations
TL;DR: Procedures for producing reuterin in sufficient amounts to isolate from a fermentation mixture and isolating this substance by high-performance liquid chromatography are described and identified as a product of glycerol fermentation associated with the production of beta-hydroxypropionic acid and trimethylene glycol.
Abstract: Lactobacillus reuteri is a prominent member of the Lactobacillus population in the gastrointestinal ecosystem of humans, poultry, swine, and other animals. Reuterin is a newly discovered, broad-spectrum antimicrobial substance produced by this species during fermentation of glycerol. In this report, we describe procedures for (i) producing reuterin in sufficient amounts to isolate from a fermentation mixture and (ii) isolating this substance by high-performance liquid chromatography. By using uniformly labeled [14C]glycerol, reuterin was identified as a product of glycerol fermentation associated with the production of beta-hydroxypropionic acid and trimethylene glycol.
421 citations
TL;DR: It is reported here that dogs with CXMD faithfully mimic the phenotype of Duchenne muscular dystrophy and that they lack the Duchennes gene transcript and its protein product, dystrophin.
Abstract: Duchenne muscular dystrophy (DMD) is the most common and the most severe of the muscular dystrophies in man. It is inherited as an X-linked recessive trait and is characterized by ongoing necrosis of skeletal muscle fibres with regeneration and eventually fibrosis and fatty infiltration. Although the gene and gene product which are defective in DMD have recently been identified, the pathogenesis of the disease is still poorly understood. A myopathy has been described in the dog which has been shown to be inherited as an X-linked trait and which is therefore a potential model of the human disease. We have studied the phenotypic expression of the disease, canine X-linked muscular dystrophy (CXMD), and have examined the molecular relationship between it and DMD. We report here that dogs with CXMD faithfully mimic the phenotype of Duchenne muscular dystrophy and that they lack the Duchenne gene transcript and its protein product, dystrophin.
418 citations
TL;DR: Analysis of linkage disequilibrium D among restriction sites or bases in DNA sequences, arising from mutations in finite populations, requires evaluation of the eighth moments of gene frequencies among two, three, and four loci, and the necessary methodology is derived here and results are computed.
410 citations
312 citations
TL;DR: In this article, a computer model of the kinetics of mechanical alloying was carried out in order to estimate the temperature effect of powder alloys during milling in a SPEX mill.
Abstract: Mechanical alloying by high energy ball milling has been observed in systems with nominally brittle components. The phases formed by mechanical alloying of brittle components include solid solutions (Si + Ge → SiGe solid solution), intermetallic compounds (Mn + Bi → MnBi), and amorphous alloys (NiZr2 + Ni11Zr9 → amorphous Ni50Zr50). A key feature of possible mechanisms for mechanical alloying of brittle components is the temperature of the powders during milling. Experiments and a computer model of the kinetics of mechanical alloying were carried out in order to esti-mate the temperature effect. Temperature rises in typical powder alloys during milling in a SPEX mill were estimated to be ≤350 K using the kinetic parameters determined from the computer model. The tempering response of fresh martensite in an Fe-1.2 wt pct C alloy during milling was consistent with the maximum results of the computer model, yielding temperatures in the pow-ders of ≤575 Ki.e., ΔT ≤ 300 K). Thermal activation was required for mechanical alloying of Si and Ge powder. No alloying occurred when the milling vial was cooled by liquid nitrogen. The pos-sible mechanisms responsible for material transfer during mechanical alloying of brittle components are considered.
289 citations
TL;DR: In this paper, the frequency properties of Wahba's Bayesian confidence intervals for smoothing splines are investigated by a large-sample approximation and by a simulation study, and the authors explain why the ACP is accurate for functions that are much smoother than the sample paths prescribed by the prior.
Abstract: The frequency properties of Wahba's Bayesian confidence intervals for smoothing splines are investigated by a large-sample approximation and by a simulation study. When the coverage probabilities for these pointwise confidence intervals are averaged across the observation points, the average coverage probability (ACP) should be close to the nominal level. From a frequency point of view, this agreement occurs because the average posterior variance for the spline is similar to a consistent estimate of the average squared error and because the average squared bias is a modest fraction of the total average squared error. These properties are independent of the Bayesian assumptions used to derive this confidence procedure, and they explain why the ACP is accurate for functions that are much smoother than the sample paths prescribed by the prior. This analysis accounts for the choice of the smoothing parameter (bandwidth) using cross-validation. In the case of natural splines an adaptive method for avo...
274 citations
TL;DR: The ability to transfer plasmid DNA via electroporation will greatly facilitate the application of recombinant DNA methodology and transposon technology to Gram‐positive bacteria for cloning and analysis of significant genes.
Abstract: Plasmid DNA was introduced by electroporation into Bacillus, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Listeria, Pediococcus, Propionibacterium and Staphylococcus as an alternative to competent-cell or protoplast transformation. Plasmid-containing transformants were recovered in these recipients at frequencies ranging from 10(1) to 10(5) transformants micrograms-1 of pGK12. Several parameters of the protocol, including DNA concentration, voltage, plating regimen and electroporation buffers were evaluated to determine conditions that improved transformation frequencies for Lactobacillus acidophilus. Using optimized conditions, the following plasmids were introduced into L. acidophilus: pAMB1, pC194, pGB354, pGKV1, pSA3, pTRK13, pTV1 and pVA797. The ability to transfer plasmid DNA via eletroporation will greatly facilitate the application of recombinant DNA methodology and transposon technology to Gram-positive bacteria for cloning and analysis of significant genes.
258 citations
01 Aug 1988
TL;DR: In this article, the authors developed an intelligent robot workstation capable of integrating data from multiple sensors, including overhead vision, eye-in-hand vision, proximity, tactile array, position, force/torque, cross-fire, overload, and slip-sensing devices.
Abstract: The objective of the authors is to develop an intelligent robot workstation capable of integrating data from multiple sensors. The investigation is based on a Unimation PUMA 560 robot and various external sensors. These include overhead vision, eye-in-hand vision, proximity, tactile array, position, force/torque, cross-fire, overload, and slip-sensing devices. The efficient fusion of data from different sources will enable the machine to respond promptly in dealing with the 'real world'. Towards this goal, the general paradigm of a sensor data fusion system has been developed, and some simulation results, as well as results from the actual implementation of certain concepts of sensor data fusion, have been demonstrated. >
TL;DR: Clinicopathologic findings from two golden retriever dogs with an inherited, progressive, degenerative muscle disease that were studied until 27 and 40 months of age are described and potential contributing pathophysiologic mechanisms are discussed in relation to Duchenne muscular dystrophy.
Abstract: Clinicopathologic findings from two golden retriever dogs with an inherited, progressive, degenerative muscle disease that were studied until 27 and 40 months of age are described. Initial clinical signs included stilted gait and simultaneous advancement of their pelvic limbs. Further gait restriction and muscle hypertrophy eventually occurred. Serum creatine kinase was dramatically elevated (greater than 10,000 U/L). There were persistent "spontaneous" high-frequency discharges (pseudomyotonia) on electromyographic evaluation. Features of both muscle fiber degeneration (hyaline fibers, myophagocytosis) and regeneration (small basophilic fibers) were seen on light microscopy. Similar ultrastructural changes (fiber hypercontraction, increased myoblasts) were present. On morphometric histochemical evaluation, mean fiber diameter of both type 1 and 2 fibers was increased compared with controls in two of three muscles examined. There was no apparent fiber type predominance. Scattered ragged red fibers were seen, but this appeared to be a nonspecific finding of either muscle fiber regeneration or degeneration. These findings and potential contributing pathophysiologic mechanisms are discussed in relation to Duchenne muscular dystrophy.
TL;DR: A second alternative nitrogenase complex (nitrogenase 3) was purified from a nifHDK deletion strain of Azotobacter vinelandii and was found to be extremely sensitive to O2, and activities could not be reproducibly maintained during freezing and thawing.
Abstract: A second alternative nitrogenase complex (nitrogenase 3) was purified from a nifHDK deletion strain of Azotobacter vinelandii. The active complex is made up of two components, dinitrogenase 3 and dinitrogenase reductase 3. Dinitrogenase 3 contains two protein subunits (alpha, Mr 58,000, and beta, Mr 50,000) which assemble into at least two active configurations: alpha 2 beta 2 (dinitrogenase 3s) and alpha 1 beta 2 (dinitrogenase 3F). Dinitrogenase 3s contains 24 Fe and 18 acid-labile S2-ions per Mr 216,000, and dinitrogenase 3F contains 11 Fe and 9 acid-labile S2-ions per Mr 158,000. Dinitrogenase reductase 3 is composed of two protein subunits of identical Mr (32,500) and contains four Fe and four acid-labile S2- ions per Mr 65,000. On two-dimensional gels, the protein subunits of the nitrogenase 3 complex comigrated with the four Mo-, V-, and NH4+-repressible proteins originally designated as N2ase B: the nitrogenase hypothesized to exist in the alternative N2 fixation system first described in 1980 (P.E. Bishop, D. M. L. Jarlenski, and D. R. Hetherington, Proc. Natl. Acad. Sci. USA 77:7342-7346, 1980). Neutron activation analysis indicated that the nitrogenase 3 complex lacked significant amounts of Mo, V, Cr, Re, and W. Some Zn, however, was found in the dinitrogenase 3S and dinitrogenase 3F preparations. The pattern of substrate reduction efficiency was H+ greater than N2 greater than C2H2. The maximum specific activity found for N2 reduction was 38 nmol of NH3 per min per mg of protein (dinitrogenase 3S). Nitrogenase 3 was found to be extremely sensitive to O2, and activities could not be reproducibly maintained during freezing and thawing. Images
24 Jul 1988
TL;DR: The authors show that a multiple-input,single-output, single-hidden-layer feedforward network with (known) hardwired connections from input to hidden layer, monotone squashing at the hidden layer and no squashingat the output embeds is a so-called Fourier network, which yields a Fourier series approximation properties of Fourierseries representations.
Abstract: The authors show that a multiple-input, single-output, single-hidden-layer feedforward network with (known) hardwired connections from input to hidden layer, monotone squashing at the hidden layer and no squashing at the output embeds as a special case a so-called Fourier network, which yields a Fourier series approximation properties of Fourier series representations. In particular, approximation to any desired accuracy of any square integrable function can be achieved by such a network, using sufficiently many hidden units. In this sense, such networks do not make avoidable mistakes. >
TL;DR: Populations of bacteria, fungi and actinomycetes in Portsmouth A 1 - and B,-soil material were affected in different ways by repeated enrichment with ferulic, p-coumaric, p -hydroxybenzoic or vanillic acids.
Abstract: Populations of bacteria, fungi and actinomycetes in Portsmouth A 1 - and B,-soil material were affected in different ways by repeated enrichment with ferulic, p -coumaric, p -hydroxybenzoic or vanillic acids. Responses varied with type of soil material and phenolic acid, phenolic acid concentration, and inorganic nutrient status of the soil. Populations changed more frequently in B 1 - than in A 1 -soil material. Phenolic acids were readily metabolized by microorganisms, sometimes without detectable population changes, when adequate mineral nutrients were present. Induction of enzymes or selection of organisms capable of degrading individual phenolic acids were clearly evident. Results imply that microbial activity in bioassay systems should be defined for allelopathic studies, particularly when results from various bioassay systems are to be compared
TL;DR: A small-scale method for the isolation of total RNA from plant tissue is described, well suited forThe isolation of RNA from large numbers of samples or from samples of limited quantity.
TL;DR: In the experimental low-input, notillage treatments, large ground beetles (Carabidae: Coleoptera) and mice preferentially fed on the larger seed species, while small carabids (Smaller Carabids: Carabidae) and dogs preferential feed on the smaller seed species.
Abstract: Weed seed consumption experiments involving comparison of rates of seed loss by seed feeders were conducted over a five-week period in low-input (no insecticide, low herbicide usage) conventional- and no-tillage soybean agroecosystems. Seeds of four broadleaf weed species (ragweed [Ambrosia artemisiifolia L.], pigweed [Amaranthus retroflexus L.], sicklepod [Cassia obtusifolia L.], and jimsonweed [Datura stramonium L.]) and one grain crop species (wheat [Triticum aestivum L.]) were provided in a free choice design at densities of 10, 25, and 50 seeds/24 cm3. Approximately 2.3 times more seeds overall, and 1.4 times more large seeds as a group were consumed in notillage systems than in conventional-tillage systems. In our experimental low-input, notillage treatments, large ground beetles (Carabidae: Coleoptera) (15–25 mm) and mice preferentially fed on the larger seed species, while small carabids (< 15 mm), ants and crickets, fed almost exclusively on the smaller seed species. Carabid beetles were responsible for more than half of all seeds consumed. Laboratory and field studies indicated that ground beetles selectively consumed specific seed species. In conventional-tillage, ants were one of the dominant consumers of seeds, suggesting different patterns of resource partitioning in each tillage system. We suggest that selective feeding by arthropod seed feeders, in combination with their high number, could affect the species composition and possibly the abundance of weeds in low-input, no-tillage agroecosystems.
TL;DR: In this paper, two computer models are described that treat the special case of orthogonal cutting, which are based on the finite element method, which is used to discretize a portion of the workpiece in the vicinity of the cutting tool.
TL;DR: It is demonstrated that an abnormality in chloride transport is present in the small intestinal and colonic epithelia of CF patients, which does not respond to either cAMP- or Ca-mediated secretagogues, and may play a role in the pathogenesis of meconium impactions in CF patients.
Abstract: Sodium ion and chloride transport was studied in vitro in small intestinal and colonic tissue from patients with cystic fibrosis (CF) and from non-CF control subjects matched as to age and sex Normal histological appearance and substantial response to mucosal glucose (5 mM, ileum) or mucosal amiloride (10(-5) M, colon) indicated normal tissue viability in both control and CF tissues Electroneutral NaCl absorption was demonstrated in the small intestine of control subjects and CF patients Small intestinal and colonic tissues of control subjects responded to four secretagogues (theophylline, 5 mM; prostaglandin E2, 10(-6) M; calcium ionophore (A23187), 10(-5) M; bethanechol, 5 x 10(-5) M), with electrogenic chloride secretion The tissues of CF patients, however, did not respond to any of the test secretagogues These studies demonstrate that an abnormality in chloride transport is present in the small intestinal and colonic epithelia of CF patients Unlike airway epithelia, which secrete chloride in response to Ca ionophore, the intestinal epithelia of CF patients do not respond to either cAMP- or Ca-mediated secretagogues This abnormality in intestinal electrolyte transport may play a role in the pathogenesis of meconium impactions in CF patients
TL;DR: In this article, a model and associated algorithm for generating maximum throughput cyclic schedules for the movements of a hoist in a PCB electroplating facility is described, which is enumerative in nature and involves the solution of linear programming subproblems.
Abstract: This paper describes a model and associated algorithm for generating maximum throughput cyclic schedules for the movements of a hoist in a PCB electroplating facility. The algorithm is enumerative in nature and involves the solution of linear programming subproblems. Computational experience with schedules for real systems is presented.
TL;DR: In this paper, it was shown that monocrystalline diamond and silicon carbide can be achieved at or below 1 atm total pressure and at a temperature T, which is the highest operating temperature ever achieved for a field effect device.
Abstract: The extreme thermal and electronic properties of diamond and of silicon carbide, and the direct band gap of gallium nitride, provide multiplicative combinations of attributes which lead to the highest figures of merit for any semiconductor materials for possible use in high power, high speed, high temperature and high frequency applications. The deposition of monocrystalline diamond, at or below 1 atm total pressure and at a temperature T , has been achieved on diamond substrates; the deposited film has been polycrystalline on all other substrates but the achievement is no less significant. For electronic applications, heteroepitaxy of single-crystal films of diamond, an understanding of mechanisms of nucleation and growth, methods of impurity introduction and activation, and further device development must be achieved. Stoichiometric gallium nitride free of nitrogen vacancies has apparently not been obtained. Thus, knowledge of the defect chemistry of this material, the growth of semiconducting films on foreign substrates, and the development of insulating layers and of their low temperature deposition as well as device fabrication procedures must be achieved. By contrast, all of these problems have already been solved for silicon carbide, including the operation of a MOSFET at 923 K — the highest operating temperature ever reported for a field-effect device. However, considerable research remains to be done regarding the development of large silicon carbide substrates, of ohmic and rectifying contacts, of new types of devices, and of low temperature techniques for the deposition of insulating layers. Fugitive donor and acceptor species in unintentionally doped samples must also be identified and controlled.
TL;DR: In this paper, it was shown that the boundedness of E ( v 11 4 ) is the weakest condition known to assure the almost sure convergence of λ max ( n ) for a class of sample covariance matrices.
TL;DR: Growth studies and acetylene reduction assays performed on two nifEN deletion strains showed that nifE and nifN are required for N2 fixation under Mo sufficiency, as previously observed, but not under conditions of Mo deficiency or in the presence of 50 nM V2O5.
Abstract: A 3.8-kilobase-pair EcoRI fragment which corrects the mutations carried by the NifB- Azotobacter vinelandii strains CA30 and UW45 was cloned, and its nucleotide sequence was determined. Four complete open reading frames (ORFs) and two partial ORFs were found. The translation product of the first partial ORF is the carboxy-terminal end of a protein homologous to the nifA gene product from Klebsiella pneumoniae. A 285-base-pair sequence containing a potential nif promoter and nif regulatory sites separates this nifA gene from the first complete ORF which encodes a protein homologous to nifB gene products from K. pneumoniae and Rhizobium species. The Tn5 insertion in strain CA30 and the nif-45 mutation of strain UW45 are located within this nifB gene. The ORF downstream from nifB predicts an amino acid sequence with a cysteine residue pattern that is characteristic of ferredoxins. No similarities were found between the translation product of the third complete ORF and those of nif genes from other organisms. At the carboxy-terminal end of the predicted translation product of the fourth complete ORF, 30 of 60 amino acid residues were identical with the sequence of the nifQ gene product from K. pneumoniae. The partial ORF located at the end of the fragment encodes the N-terminal part of a potential protein with an unknown function. Northern (RNA) blot analysis indicated that transcripts from the region containing the four complete ORFs were NH4+ repressible and that the transcription products were identical in cells derepressed under conditions of Mo sufficiency or Mo deficiency or in the presence of vanadium. In contrast to the NifB- strain CA30, which is Nif- under all conditions, mutants that carry mutations affecting the C-terminal end of nifB or genes located immediately downstream from nifB, grew under all N2-fixing conditions. However, in the presence of Mo, most of the strains required 1,000 times the amount of molybdate that is sufficient for maximal growth of the wild-type strain CA under N2-fixing conditions. Growth data from strain CA37, which carries a Kanr insertion in nifQ, indicate that nifQ in A. vinelandii is not required for N2 fixation in the presence of V2O5 or under Mo-deficient conditions. Growth studies and acetylene reduction assays performed on two nifEN deletion strains showed that nifE and nifN are required for N2 fixation under Mo sufficiency, as previously observed (K. E. Brigle, M. C. Weiss, W. E. Newton, and D. R. Dean, J. Bacteriol. 169:1547-1553, 1987), but not under conditions of Mo deficiency or in the presence of 50 nM V2O5.
TL;DR: Recent developments in the mechanism of regulation of the manganese-containing superoxide dismutase of Escherichia coli will certainly open new research avenues to better understand the regulation of SODs in other organisms.
TL;DR: The results implicate the 13-kilodalton polypeptide in conferring toxin sensitivity to mitochondria of cms-T maize and appear to be essential for proper interaction with the BmT-toxin and methomyl.
Abstract: The Texas male-sterile cytoplasm (cms-T) of maize carries the cytoplasmically inherited trait of male sterility. Mitochondria isolated from cms-T maize are specifically sensitive to a toxin (BmT-toxin) produced by the fungal pathogen Bipolaris maydis, race T, and the carbamate insecticide methomyl. A mitochondrial gene unique to cms-T maize, which produces a 13-kilodalton polypeptide associated with cytoplasmic male sterility, was expressed in Escherichia coli. After addition of BmT-toxin or methomyl, inhibition of whole cell respiration and swelling of spheroplasts were observed in Escherichia coli cultures producing the novel mitochondrial protein; these effects are similar to those observed with isolated cms-T mitochondria. The amino-terminal region of the 13-kilodalton polypeptide appears to be essential for proper interaction with the BmT-toxin and methomyl. These results implicate the 13-kilodalton polypeptide in conferring toxin sensitivity to mitochondria of cms-T maize.
TL;DR: In this paper, a permanent magnet synchronous-motor drive that uses and adaptive control to find the maximum efficiency operating point at any speed and load is demonstrated, where active damping is provided by modulating the inverter frequency in proportion to the perturbations in the average inverter DC link current.
Abstract: A permanent magnet synchronous-motor drive that uses and adaptive control to find the maximum-efficiency operating point at any speed and load is demonstrated. Active damping is provided by modulating the inverter frequency in proportion to the perturbations in the average inverter DC link current. All principal control functions, including efficiency optimization and frequency modulation, are performed by a real-time digital control algorithm, using only the filtered inverter DC link current as a feedback signal from the inverter. Laboratory tests and computer simulations demonstrate the performance of the efficiency-optimizing control and the frequency-modulation feedback loop. >
TL;DR: In this article, the basic techniques and procedures have been worked out for propagation of several marsh angiosperms, and a variety of locations to vegetate intertidal dredged material disposal sites, stabilize shorelines, mitigate damage to natural marshes and to revegetate one marsh destroyed by an oil spill.
TL;DR: In this article, the authors measured the dry weight of macroorganic matter (MOM), soil bulk density, pH, humic matter, and extractable P in natural and transplanted estuarine marsh soils.
Abstract: Total nitrogen, phosphorus and organic carbon were compared in natural and transplanted estuarine marsh soils (top 30 cm) to assess nutrient storage in transplanted marshes. Soils were sampled in five transplanted marshes ranging in age from 1 to 15 yr and in five nearby natural marshes along the North Carolina coast. Dry weight of macroorganic matter (MOM), soil bulk density, pH, humic matter, and extractable P also were measured. Nutrient pools increased with increasing marsh age and hydroperiod. Nitrogen, phosphorus and organic carbon pools were largest in soils of irregularly flooded natural marshes. The contribution of MOM to marsh nutrient reservoirs was 6–45%, 2–22%, and 1–7% of the carbon, nitrogen and phosphorus, respectively. Rates of nutrient accumulation in transplanted marshes ranged from 2.6–10.0, 0.03–1.10, and 84–218 kmol ha−1yr−1 of nitrogen, phosphorus and organic carbon, respectively. Accumulation rates were greater in the irregularly flooded marshes compared to the regularly flooded marshes. Approximately 11 to 12% and 20% of the net primary production of emergent vegetation was buried in sediments of the regularly flooded and irregularly flooded transplanted marshes, respectively. Macroorganic matter nutrient pools develop rapidly in transplanted marshes and may approximate natural marshes within 15 to 30 yr. However, development of soil carbon, nitrogen and phosphorus reservoirs takes considerably longer.
TL;DR: In this article, the effects of winter storms and the Gulf Stream on the spawning, development and drift of the Atlantic menhaden, Brevoortia tyrannus, were investigated.
Abstract: Recruitment for many marine organisms depends on survival and transport of eggs and larvae from spawning grounds to nursery areas1. We investigated the effects of winter storms and the Gulf Stream on the spawning, development and drift of the Atlantic menhaden, Brevoortia tyrannus, which spawns offshore2 and metamorphoses in estuaries3. Spawning was maximal during storms in water upwelled near the western edge of the Gulf Stream. Eggs and larvae drifted shoreward with abundant food in the warm surface stratum of a density-driven circulation maintained by the large sea–air heat flux. We suggest that the Atlantic menhaden and other species have evolved to reproduce in winter near warm boundary currents, including the Gulf Stream and Kuroshio, as a result of physical conditions that permit the rapid development and shoreward drift of their eggs and larvae, with consequent high recruitment and fitness.
TL;DR: In this paper, a simple macroscopic model for the two-phase flow is analyzed to examine whether this regime transition should be viewed as the loss of stability of a steady state or loss of existence of any solution for the steady-state equations of motion.
Abstract: In cocurrent downflow of a gas and a liquid through a packed column, a transition from trickling flow to pulsing flow is observed as one increases the flow rates. A simple macroscopic model for the two-phase flow is analyzed to examine whether this regime transition should be viewed as the loss of stability of a steady state or the loss of existence of any solution for the steady-state equations of motion. The former appears to be a more reasonable interpretation and an explicit algebraic criterion for the onset of pulsing is presented.