bluuebunny/crossref_metadata_2025 huggingface dataset:
Respiratory responses to preoptic/anterior hypothalamic warming during sleep in kittens
Authors: Ni H , Schechtman VL , Zhang J , Glotzbach SF , Harper RM
Published: October 2005

The preoptic/anterior hypothalamic (POAH) area of 12-48-day-old unanaesthetized, unrestrained kittens was warmed with a diathermic probe to assess respiratory responses to a central thermal challenge during sleep. During quiet sleep (QS), warming of the POAH by 1.4-3.8 degrees C induced periods of tachypnoea (panting) interspersed with periods of slower respiration; the percentage of time spent in panting increased as the kittens matured. During rapid eye movement (REM) sleep, POAH warming induced a much smaller increase in respiratory rate and no sustained panting. Analysis of the dynamics of panting (in QS only, since panting did not occur in REM) revealed several changes from breathing patterns of normal respiration. During panting, the increased respiratory rate did not result from equal changes in inspiratory and expiratory times; inspiratory times accounted for a larger portion of the decline in total respiratory cycle time. Amplitude of diaphragmatic electromyographic activity showed an age-dependent response to thermal panting, which resulted in age-dependent changes in ventilation and inspiratory drive. The interspersion of slower with faster respiratory rates suggests a competition of thermoregulatory and respiratory homeostatic mechanisms. The age-dependent ventilatory responses to thermal panting suggest greater vulnerability to thermal stress at particular ages, and may have implications for the sudden infant death syndrome.
Pulsatile release of oxytocin in newborn infants
Authors: Marchini G , Stock S
Published: October 2005

Recently, a pulsatile, basal oxytocin blood level has been described in human adults. To investigate if such a hormone profile exists already during the neonatal period, we collected blood samples continuously with 20-s fractions for 4 min in 1-day-old infants (n = 26). Plasma oxytocin concentrations were determined by a specific radioimmunoassay. The values were further analysed by the pulse detection program PULSAR. We found that 42% of the infants presented one peak in the oxytocin level during a 4-min period. The peak constituted a 111 +/- 66% (mean +/- SD) increment of the baseline value. It is suggested that the release of oxytocin during basal conditions occurs in a pulsatile way in newborn infants and that these hormone pulses reflect fluctuations in the activity of the hypothalamic neurosecretory cells.
Transvascular albumin transport and protein replenishment after haemorrhage in the chronically catheterized pregnant rabbit
Authors: Valenzuela GJ , Iacampo K , Rauld HF
Published: October 2005

Pregnancy is characterized by increases in both blood and interstitial volumes, but the mechanisms are unknown. To test the hypotheses that blood volume (BV) recovery after haemorrhage in pregnant (P) is faster than in nonpregnant (NP) rabbits, and that this can be explained by a higher capillary filtration, a 20% BV haemorrhage was produced in a group of 7 P and 7 NP rabbits. We determined the BV recovery (measured by 99Tc), the total plasma protein mass and the haematocrit at 10, 20, 30, 60 and 1440 min after haemorrhage. Arterial and venous pressures and heart rate were measured during a 30-min control period, during the 10 min of haemorrhage, and for the following 70 min. In a separate group of P and NP rabbits, 125I-labelled albumin was infused and blood samples were obtained at 10, 20, and 30 min. Capillary filtration was expressed as the percentage of radioactive albumin that left the intravascular space after 30 min. No differences were found in the rate of BV recovery, arterial and venous pressures, or heart rate response between P and NP animals (P > 0.1). By 24 h total plasma protein mass (TPPM) was significantly increased above baseline in the P rabbits by an average+SEM of 13 + 3.7%, but not in NP rabbits (5 + 4.5%). At 30 min, the amount of labelled albumin in the intravascular space decreased by 15.4 + 3.4% for Pv. 8.2 + 1.2% for NP rabbits (P < 0.05). There was a high correlation between TPPM recovery and BV recovery in the P (r = 0.96) and NP rabbits (r = 0.95). In conclusion, we did not find differences in the rate at which the BV recovered during pregnancy, despite the increased capillary permeability. During pregnancy, the combination of the latter with an increase in the TPPM elevation above pre-haemorrhage levels suggests a faster rate of protein mobilization.
Studies in sheep examining plasma follistatin elevations due to frequent blood sampling or surgery
Authors: Klein R , Robertson DM , Clarke IJ
Published: October 2005

This study examined the effects of the anticoagulant heparin on plasma follistatin (FS) concentrations used during blood sampling in Corriedale ewes. Plasma FS concentrations increased acutely (P < 0.01) following a bolus intravenous injection of heparin (3200 U). To determine whether frequent sampling per se can also increase plasma FS concentrations, ewes were sampled using a substitute anticoagulant, ethylenediamine tetraacetic acid. Frequent sampling had no effect on plasma FS concentrations. alpha-2 Macroglobulin concentrations were measured before and after bilateral ovariectomy and sham ovariectomy to determine whether this agent causes an increase in plasma FS concentrations 10-12 h after laparotomy. No differences in plasma alpha-2 macroglobulin concentrations were observed at the time of the observed increase in plasma FS concentrations. In conclusion: (1) heparin caused acute elevations in plasma FS concentrations probably by binding to FS, thereby reducing its plasma clearance; (2) rapid blood sampling per se did not elevate plasma FS concentrations; (3) alpha-2 macroglobulin concentrations were not elevated at the same time as plasma FS concentrations 10-12 h after surgery; and (4) the small increase in alpha-2 macroglobulin concentrations before surgery was attributable to a stress-induced response as seen in other species.
Increased secondary sex ratios in golden hamster litters sired by males without coagulating glands and seminal vesicles
Authors: Chow PH , Cheung MP , O WS
Published: October 2005

In golden hamsters, although bilateral ablation of paternal coagulating glands (CGX) and seminal vesicles (SVX) did not affect fertility, a higher number of male pups were born. The present study aimed at determining whether this male-biased sex ratio was due to an imbalance of fertilization by X and Y chromosome-bearing sperms or whether it was the consequence of a sex-related differential survival of embryos. The sex of embryos sired by sham-operated (SH) controls or males subjected to bilateral ablation of ampullary glands (AGX), CGX and SVX was determined from chromosomal spreads at 10 h post coitum and 10 days post coitum. The primary sex ratio of of the SH group did not deviate from the hypothetical sex ratio of 1:1. The sex ratios of zygotes from the three experimental groups did not differ from that of the controls. However, by mid gestation, the sex ratio was significantly higher in the SVX group (P < 0.05) and the CGX group (P < 0.005). The absence of secretions from the ampullary gland, coagulating gland and seminal vesicle had no effect on the primary sex ratio, thus these glands did not appear to affect fertilization by the X and Y chromosome-bearing sperm. The increased secondary sex ratios observed in the SVX and CGX groups were due to the preferential survival of males.
Development of the spleen as a red blood cell reservoir in lambs
Authors: Potocnik SJ , Wintour EM
Published: October 2005

In adult sheep and other animals the spleen is a reservoir of red blood cells (RBCs), which can be mobilized by adrenaline-induced splenic contraction. Adrenaline does not increase the haematocrit in the ovine fetus. This study examined the development of a releasable store of RBCs in the spleen of lambs during the neonatal period. Spleen and body weights were measured in 126 fetuses and lambs, ranging in age from 60 days' gestation to 94 days post partum. Spleen weight, as a percentage of body weight, stabilized at 0.56 +/- 0.02%, 20 days post partum. Adrenaline infusion (5 mg kg-1 min-1) was associated with a mean increase in arterial haematocrit (Hct) of 7.6 and 5.8 Hct % in lambs at 20-24 and 50-52 days of age respectively (n = 4 at each age). The spleen in lambs has become a significant reservoir of RBCs by 20-24 days of age and may contain reserves equivalent to those in adult sheep. This splenic reserve is developed before the post-natal drop in haematocrit occurs.
Effects of lung expansion on lung liquid production in vitro by lungs from fetal guinea-pigs. I. Basic studies and the effects of amiloride and propranolol
Authors: Nelson PG , Perks AM
Published: October 2005

Lungs from near-term fetal guinea-pigs were supported in vitro for 3 h; lung liquid production was measured by a dye-dilution method using Blue Dextran 2000 (fetuses 62 +/- 2 days of gestation, 97.6 +/- 19.0 (SD) g body weight; n = 134). Untreated control preparations produced fluid at 1.30 +/- 0.22 ml/kg body weight per h, and showed no significant changes during incubation (n = 30). After 1 h of incubation, experimental lungs were expanded with Krebs-Henseleit saline in volumes estimated to be below or approximating those of the first breath (n = 30; first breath, 0.6-1.2 ml). Expansions were graded at 18 +/- 4%, 31 +/- 4%, 43 +/- 3%, 50 +/- 3% and 72 +/- 2% of lung volume (volumes used for expansion at the maximal level, 0.64 +/- 0.25 ml). All expansions of 31% or above produced reductions in fluid production significant by analysis of variance (P < 0.01-0.001); production halted at 50% expansion, and there was strong reabsorption at 72% expansion (-0.87 +/- 0.45 ml/kg body weight per h by the final hour). There was an exponential relationship between percentage expansion and percentage fall in production (r = 1.00). There was no evidence for excessive pressure, and no evidence for lung damage as judged by electron microscopy or entry of intracellular materials into the fluid (lactic dehydrogenase, protein, K+). In studies based on 36 preparations, 10(-6) M amiloride present in the lung lumen (apically) abolished the reabsorptions seen at 70 +/- 3% expansion, but not the arrest of production; it had no effect on control preparations. Studies based on 24 preparations showed that responses to 72 +/- 2% expansion were not affected by 10(-7) M propranolol placed in the outer saline. In studies of 14 fetuses of widely different body weights (68.3-124.9 g), responses to 74 +/- 2% expansion showed an exponential increase with increasing body weight (r = 0.96). Although caution is needed, the results suggest that expansion of the lungs at birth may induce fluid reabsorption by an action independent of tissues outside the lungs, probably involving both activation of a Na(+)-based reabsorptive system and arrest of production, but not requiring beta-receptor activation. The probability that the responses are maximal at birth is discussed, and it is suggested that the effect of expansion may be a specialization of the perinatal lung.
Liquid ventilation in premature lambs: uptake, biodistribution and elimination of perfluorodecalin liquid
Authors: Shaffer TH , Wolfson MR , Greenspan JS , Hoffman RE , Davis SL , Clark LC
Published: October 2005

Perfluorochemical (PFC) liquids are biologically inert and nonbiotransformable substances that, when used as breathing medium, may be transported across the lung epithelium in small quantities, distributed throughout the body, and ultimately vapourized through the lungs and transpired through the skin. To further evaluate the uptake, biodistribution and elimination of a PFC liquid (perfluorodecalin) in the neonatal population, arterial blood, tissue and expired gas samples were obtained from preterm lambs (105-114 days gestation). Two groups of premature lambs were studied: Group I (n = 4) lambs were liquid ventilated from birth for 1 h and killed without exposure to gas ventilation (GV) and Group II (n = 5) lambs were liquid ventilated for 1 h followed by up to 2 h of GV. Samples were analysed by electron-capture gas chromatography and data were expressed in nl of PFC/ml of blood or gas and nl of PFC/gm tissue. During liquid ventilation and subsequent GV, PFC blood levels significantly increased (P < 0.001) from baseline control levels (0.007 +/- 0.001 SE nl PFC/ml blood) to a high of 2.95 +/- 1.03 SE nl PFC/ml blood. Perfluorochemical levels measured in expired gas (Group II) demonstrated a rapid decrease as a function of time of GV. Tissue levels of PFC indicated that uptake of PFC in Group I was significantly different (P < 0.001) than baseline levels and organ dependent; the highest levels were in the lungs (221 +/- 26.2 SE nl PFC/g tissue) and the lowest in the liver (2.24 +/- 1.6 SE nl PFC/g tissue). Comparison of tissue levels of PFC between groups indicated a 34.8% mean decrease across organs in Group II compared with Group I. These data indicate that PFC uptake and elimination is organ dependent and that PFC liquids can be eliminated through the lungs upon return to GV. Sustained PFC blood levels may be related to residual PFC in the organs and lung as well as regional variation in ventilation-perfusion matching upon return to GV.
Ontogeny of FAD-linked glycerophosphate dehydrogenase in rat pancreatic islets
Authors: Rasschaert J , Malaisse WJ , Tanigawa K
Published: October 2005

The activities of the mitochondrial FAD-linked glycerophosphate dehydrogenase (m-GDH), glutamate dehydrogenase, alpha-ketoglutarate dehydrogenase, glutamate-pyruvate transaminase (GPT) and glutamate-oxaloacetate transaminase were measured in islet and liver homogenates from fetal, neonatal, adult male, adult female, pregnant and lactating rats. Either parallel or dissociated ontogenic changes were observed in islet and liver homogenates. The activity of islet m-GDH was slightly, albeit not significantly, lower in neonates than in adult rats, comparable in male and female adult animals, unaffected by pregnancy, and increased during lactation. It was much higher in fetal or adult islets cultured for 7 days than in freshly isolated islets from adult rats. In cultured islets from adult rats, the increase in m-GDH activity coincided with a dramatic decrease of GPT activity, a situation the mirror image of that found in several animal models of non-insulin-dependent diabetes mellitus. The intrinsic properties of m-GDH, as judged by comparison of measurements made by either a radioisotopic or a colorimetric procedure, were not identical in islet and liver homogenates and differed between fetal and adult islets, suggesting the existence of distinct iso-enzymes. These findings illustrate adaptive changes of islet enzymes, with exclusive or partial mitochondrial location, in ontogenic situations characterized by a remodelling of fuel homeostasis.
What marsupial gametes disclose about gamete function in eutherian mammals
Authors: Bedford JM
Published: October 2005

The gametes of eutherian mammals present some fundamental enigmas in regard to their structure and behaviour that have not been solved by a focus on the Eutheria alone. Although the evidence is limited still, some clues are suggested in comparison with representative American and Australian marsupials, whose gametes have undergone parallel, although sometimes quite different, evolutionary changes to those of eutherian mammals. The contrasts between them illuminate basic questions about the functions of the epididymis and sperm capacitation, about sperm numbers and sperm production, about the function of the cumulus oophorus and the configuration of the Fallopian tube and, not least, about gamete design and its bearing on the mechanisms by which spermatozoa penetrate the egg coat.
Capacitation and the acrosome reaction in marsupial spermatozoa
Authors: Mate KE , Rodger JC
Published: October 2005

Although yet to be established definitively, it appears that marsupial spermatozoa require a process of capacitation and that the mechanisms involved may be quite different between the Australian and American species. For Australian species, failure to induce this functional event in culture has meant that in vitro fertilization (IVF) is yet to be achieved. However, in the American species with paired spermatozoa, IVF and subsequent embryo development have been obtained under quite simple culture conditions. Our understanding of the interactions of marsupial spermatozoa with the female tract, and in particular the oviduct, the most likely site of capacitation, is discussed. Although the acrosome reaction (AR) is an equally critical event in marsupial fertilization it appears to be regulated quite differently. The uniquely stable character of the marsupial acrosome is examined as well as our current understanding of the regulation of the marsupial sperm AR in vivo and in vitro.
Fate-map analysis of the epiblast of the dasyurid marsupial Sminthopsis macroura (Gould)
Authors: Cruz YP , Yousef A , Selwood L
Published: October 2005

Allocation of cells in the marsupial epiblast to embryonic and extra-embryonic domains has to date been studied only histologically. An unresolved issue in marsupial embryology has been the existence of a medullary plate. We re-examined the hypotheses that the medullary plate, or neurectoderm, arises before notochord formation and that the integumentary ectoderm is segregated from the ectoderm after the formation of the medullary plate. By marking epiblast cells in 65 Day-8 embryos of the dasyurid marsupial Sminthopsis macroura, with the lipophilic cell-surface marker, DiI, we demonstrated that the so-called medullary plate contains progenitors of the integumentary ectoderm of the neck, chest, limbs and flank of the embryo. Thus, cell-allocation processes in the epiblast must have segregated the entire complement of embryonic ectoderm in one event, not separate events. It is concluded that the embryonic structure called 'medullary plate' in marsupial embryos is misnamed since, in fact, it consists of both integumentary ectoderm and neurectoderm.
Intracellular pH monkey embryos at various stages of organogenesis estimated by dimethadione distribution
Authors: Collins MD , Scott WJ , Hendrickx AG , Peterson PE , Nau H
Published: October 2005

Previous experiments using the transplacental distribution of 14C-DMO (5,5-dimethyloxazolidine-2,4-dione or commonly known as dimethadione) have demonstrated that the pH of rat embryos and fluids progressively decreases during organogenesis. The aim of the present experiments was to similarly evaluate pH changes during organogenesis in the cynomolgus monkey, which is a model for human embryogenesis. Using DMO quantitated by gas chromatography-mass spectrometry as opposed to the counting of radiolabelled compound, cynomolgus monkey embryos were determined to undergo a similar decrease in embryonic pHi over an approximately comparable period of development (Days 24-36 of gestation). The ratio of DMO in chorionic fluid to DMO in maternal plasma in the cynomolgus monkey also displayed a decrease with advancing gestational age indicative of a pH decrease. The DMO transplacental distribution was found to be significantly slower in the cynomolgus monkey than that in rodents. The present investigation indicates that the magnitude of the reduction of pH in embryonic cells and in extra-embryonic fluids over a period of organogenesis in the cynomolgus monkey is similar to the reduction detected in rodent embryos and fluids over a comparable developmental period, but the relative gradient between maternal blood pH and embryonic intracellular pH is different. The difference in the pH gradient between the two species may lead to differential transplacental distribution of exogenous and endogenous substances.
Localization by indirect immunofluorescence of nitric oxide synthase in mouse and human spermatozoa
Authors: Herrero MB , Perez Martinez S , Viggiano JM , Polak JM , de Gimeno MF
Published: October 2005

The localization of nitric oxide synthase was studied in mouse epididymal spermatozoa and freshly ejaculated human sperm. A rabbit antiserum against the neuronal isoform of the enzyme was used, and antibody binding was detected with a fluorescein isothiocyanate-conjugated polyclonal antibody specific for rabbit IgG. In mouse spermatozoa, the percentage of cells staining specifically ranged from 88% to 98%. Samples were examined after 0-, 90- and 150-min incubations in vitro. Three different patterns of staining were observed: (a) Pattern I, intense fluorescent staining localized in the acrosome and in a segment of the tail; (b) Pattern II, fluorescent staining localized only in the tail; and (c) Pattern III, faint fluorescent staining localized in the acrosomal cap and in the tail. The potential physiological significance of these patterns is discussed. Nitric oxide synthase was also localized in the acrosome of freshly ejaculated human sperm.
Consumption of amino acids by bovine preimplantation embryos
Authors: Partridge RJ , Leese HJ
Published: October 2005

Bovine embryos produced in vitro from the putative zygote stage to the blastocyst stage, and blastocysts freshly flushed from the uterus, were cultured in a physiological mixture of amino acids. Depletion of amino acids from the medium and, in a few cases, their appearance, was measured by high performance liquid chromatography. Amino acids were depleted at widely differing rates. The depletion of amino acids was higher when embryos at later developmental stages were cultured, implying an increase in amino acid requirement with development. Threonine was the only amino acid to be depleted at all stages of development; depletion increased from 0.18 +/- 0.07 pmol embryo-1 h-1 at the putative zygote stage to 1.96 +/- 0.49 pmol embryo-1 h-1 at the blastocyst stage. Glutamine was depleted at the putative zygote stage and the 4-cell stage (0.76 +/- 0.05 and 0.94 +/- 0.10 pmol embryo-1 h-1 respectively), but was not significantly depleted at the later stages. Alanine was the only amino acid that appeared consistently in the medium and its production increased progressively throughout development. Aspartate, glutamate, threonine and lysine were depleted significantly by blastocysts derived both in vitro and in vivo; the embryos in vivo also depleted arginine, phenylalanine, isoleucine and tyrosine. These results indicate that individual amino acids are depleted at different rates by bovine preimplantation embryos and suggest that amino acid requirements change during development.
Effects of bovine somatotrophin (bST) on ovarian function in post-partum beef cows
Authors: Andrade LP , Rhind SM , Wright IA , McMillen SR , Goddard PJ , Bramley TA
Published: October 2005

The effects of bovine somatotrophin (bST) on ovarian follicle development and function and associated gonadotrophin profiles during the first nine weeks post partum were investigated in beef cows. Thirty-two cows (Shorthorn x Galloway) in moderately low body condition (BC) at calving were fed to maintain BC thereafter. At Weeks 2, 4, 6 and 8 post partum, animals were injected with 320 mg bovine somatotrophin (bST) (T, treated; n = 17) or with the carrier oil only (C, control; n = 15). Ovulation occurred in 4 of 17 T cows and 0 of 15 C cows (P = 0.10) by nine week post partum. Treatment with bST did not affect the numbers of small (3-8 mm in diameter) or large (> 8 mm in diameter) follicles or the granulosa cell populations but enhanced the oestradiol (P < 0.05) and insulin-like growth factor-I (IGF-I) content (P < 0.01) of large follicles by nine weeks post partum. It did not significantly affect the testosterone concentrations of large follicles. Circulating concentrations of growth hormone (GH) and IGF-I were higher in T cows than in C cows (P < 0.001) but were unrelated to gonadotrophin profiles or gonadotrophin receptor concentrations in the follicles. At Week 8, plasma insulin concentrations were higher in T cows than in C cows both before (P < 0.05) and after (P < 0.05) glucose injection. It is concluded that GH may play an important role in mediating the effects of nutritional state on ovarian function during the post-partum period, possibly through alteration of intrafollicular IGF-I concentrations.
Fructose stimulates shedding of cytoplasmic droplets from epididymal boar spermatozoa
Authors: Harayama H , Shibukawa T , Miyake M , Kannan Y , Kato S
Published: October 2005

The aim of the present study was to establish the presence of an inducer(s) for the shedding of cytoplasmic droplets from boar spermatozoa after ejaculation. Cauda epididymal spermatozoa were incubated with seminal plasma, seminal vesicular fluid (SVF) or chemical agents at 39 degrees C for 30 min. After fixation and staining, percentages of spermatozoa without a droplet were determined. In the samples incubated with seminal plasma, SVF and a filtrate of SVF obtained after passage through an ultrafilter (molecular weight cut-off, 10,000), 43%, 60-69% and 43% of the spermatozoa were without a droplet respectively. The percentage of spermatozoa without a droplet after incubation with D-fructose (1.0 mM), which was one of the energy substrates included in SVF, was 76%. Furthermore, percentages increased to 93% and 90% with the addition of caffeine (2.0 mM) and N6, 2'-O-dibutyryl cyclic adenosine 3',5'-monophosphate (1.0 mM), respectively, but decreased to 48% with the addition of imidazole (2.0 mM). Based on these results, it is suggested that the shedding of cytoplasmic droplets from boar spermatozoa is induced by fructose originating from SVF. It also appears that this event is mediated by increasing the concentration of intracellular cyclic adenosine 3',5'-monophosphate.
Predicting Behavior of the 1988 Yellowstone Fires: Projections versus Reality
Authors: Rothermel RC
Published: October 2005

An account is presented of the initial longrange, 30-day, projections of fire growth of the wildfires in the Greater Yellow stone Area in 1988. The request for information, the method of prediction, and the actual fire growth are discussed and documented with maps. The difficulties and uncertainties of long-range fire prediction are discussed with suggestions for improving the process and comments on new research products available or being developed that could aid this process.
Is Arson Associated with Severe Fire Weather in Southern California?
Authors: Mees R
Published: October 2005

Under severe fire weather conditions arson is believed to be the primary cause of large wildland fires in southern California. Wildland fire suppression personnel and the public use the the expression "This weather brings out the arsonists" to indicate their awareness of the high potential for large arson-caused fires under these conditions. To determine the accuracy of this statement, fire occurrence and weather data were analyzed for four southern California National Forests for a 10-year period (1975–1984). The results showed that the proportion of arson and non-arson person-caused fires remained the same under most fire-danger
conditions; however, a much higher percentage of arson fires became large fires when fire danger was severe. Furthermore, the timing of the arsonist contributed to the frequent occurrence of large arson fires. The data presented here refute the idea that most arson fires occur under severe weather conditions and at the same time-validate the utility of maintaining arson prevention programs during most weather conditions.
Basal Injury From Smoldering Fires in Mature Pinus ponderosa Laws
Authors: Ryan KC , Frandsen WH
Published: October 2005

Fuel accumulations were measured in duff mounds around the bases of 19 mature Pinus ponderosa Laws. (ponderosa pine) in a 200-year-old stand in Glacier National Park, Montana. Tree diameter at breast height ranged from 50 to 114 cm (mean = 80 cm). The stand burned at intervals between 13 to 58 years prior to European settlement. This stand had not burned for 69 years. The duff depth 30 cm from the tree bole ranged from 3 to 39 cm (mean = 18 cm). Duff depth increased with tree diameter and decreased with distance from the bole. Duff depth 90 cm from the bole averaged one-half the depth 30 cm from the bole. Duff consumption and its effect on cambium mortality were quantified following a late summer, low intensity fire. Duff moisture contents on a dry weight basis were: fermentation (20%) and humus (36%). Smoldering combustion consumed98% of the duff beneath the trees. Two patterns of duff burning were documented: downward spreading and lateral spreading. Temperatures near the
root crown were above 300�C for 2 to 4 hours, resulting in mortality of 45% of the cambium samples (n = 76) tested at the root crown. The probability of cambium mortality increased with duff depth and tree diameter. However, cambium mortality was lower than expected from analysis of thermal diffusion through bark. Cooling by mass transport through phloem and xylem is suggested as apossible explanation for the low cambium mortality.
Initial Floristics in Lodgepole Pine (Pinus contorta) Forests Following the 1988 Yellowstone Fires
Authors: Anderson JE , Romme WH
Published: October 2005

The Yellowstone fires of 1988 produced a mosaic of Pinus contorta stands subjected to fire of varying severities. In August, 1989, we inventoried density of vascular plants in paired plots at seven burned stands. One plot was in a severe canopy bum; the paired plot was in an adjacent area that burned at moderate severity. Density of vascular plants was consistently
higher in moderate than in severe burn plots. At all sites, floristic composition largely reflected the species present before the fire. Two-thirds of the individuals present in the first postfire season were from vegetative regrowth of plants that survived the fire; of the remaining third, most
were P. contorta seedlings. Fire severity had a strong influence on seedling density; at all sites, P. contorta seedling density was higher in the plot classified as a moderate bum. P. contorta seedling density was not related to that of potential competitors. Within sites, the key variable explaining differences between moderate and severe plots is probably loss of seeds consumed or killed by severe canopy fires; differences among sites are likely a consequence of availability of seeds at the time of the fire, a function of the proportion of serotinous trees in the stand.
Wall Shear-Stress as a Parameter to Correlate the Rate of Spread of a Wind Induced Forest Fire.
Authors: Viegas DX , Neto LPC
Published: October 2005

Modelling of the wind effect on the rate of
spread of a flame in a forest fire usually employs a wind
velocity measured at mid-flame height. An alternative
formulation is proposed in this paper, based on the wall
shear-stress produced by the wind on the fuelbed in the
absence of combustion. Some tests performed on a labo
ratory scale are described and the results obtained to
gether with those from other sources confirm the possi
bility of using wall shear-stress to correlate the rate of
spread of a flame front.
Relating Burning Index to Wildfire Workload Over Broad Geographic Areas
Authors: Mees R , Chase R
Published: October 2005

The burning index of the National Fire Danger
Rating System is designed to measure potential fire
workload over broad geographic areas that can be repre
sented as being homogeneous with respect to fuel, topo
graphic, and weather conditions. The utility of this index
is confirmed by its relation to three measures of fire
workload-number of fires, area burned, and number of
personnel used in fire suppression for National Forests
in southern California. The distributions of these mea
sures over 15 years were skewed heavily to the right
("heavy-tailed distributions"). We selected the75 th, 90th,
and 95th percentile values of each distribution at ten
percentile values of the burning index to investigate and
display the association between fire workload and the
burning index. The results provide a distinct view of the
direct relationship between wildfire workload and critical
burning index values for the southern California area as
a whole, and point to the potential value of this approach
for anticipating fire control problems in other areas.
Toward a Comprehensive Wildlife Spread Model
Authors: Weber RO
Published: October 2005

The mathematical structure of a model of a spreading wildfire which includes chemical kinetic effects, as well as heat transfer, is outlined in general terms. Reference to a simple example which has been intensively studied demonstrates some of the salient features. A more realistic example and its analysis is also presented. One key feature of the more realistic models is the prediction of conditions under which a fire will not bum. The coupling of these models with further fire chemistry studies is promising for physical models of wildfire spread. Elliptical fire shapes arise as the solution of the proposed equations in two dimensions.
The Relationship of Forest Fires to Agro-Forestry and Socio-Economic Parameters in Portugal
Authors: de Almeida AMS Ferreira , e Moura PVS Vilaça
Published: October 2005

Forest fires are increasing every year in Portugal. Trying to understand more about their causes, we collected available forest fires data, as well as agroforestry and socio-economic parameters considered to be closely related to them, in all the 274 administrative regions (councils). Using multivariate analysis (principal components analysis and classification) we established 8 groups of councils defined by the identity of response of the analysed variables. We were, therefore, able to determine which parameters mainly influenced each group, and that knowledge could be a starting point to fire prevention.
Improved Fire Growth Modeling
Authors: Ball GL , Guertin DP
Published: October 2005

Recent developments in the use of GIs for
spatial dynamic modeling has resulted in improved fire
growth simulations. This paper examines previous growth
models and some of their weaknesses. We then define
what would be required to handle the growth of surface
fire within a raster based GIS program. The paper
discusses the requirements for the algorithm needed to
model fire growth and how this algorithm is implemented
using the PROMAP GIS modeling extensions. Examples
are given of fire growth simulation using predefined
conditions. The need for further testing of actual fires is
discussed.
Simulations of Horizontal Roll Vortex Development Above Lines of Extreme Surface Heating
Authors: Heilman WE , Fast JD
Published: October 2005

A two-dimensional, nonhydrostatic, coupled,
earth/atrnospheric model has been used to simulate mean
and turbulent atmospheric characteristics near lines of
extreme surface heating. Prognostic equations are used to
solve for the horizontal and vertical wind components,
potential temperature,and turbulent kinetic energy (TKE).
The model computes nonhydrostatic pressure deviations
from a derived atmospheric continuity equation. Hori-
zontal pressure gradients generated from surface heating
are calculated from thermal wind principles.
Model simulations indicate the development of buoyancy-induced horizontal roll vortices near regions with
surface temperatures typical of wildland fires. Model
results are qualitatively similar to previous wind-tunnel
experiments. When surface temperatures are increased,
the circulations associated with the roll vortices become
more vigorous. The introduction of a weak ambient flow
in a direction perpendicular to the line of heating has a
major influence on the simulated circulation patterns aid
nonhydrostatic pressure deviations near the line of heating. The effect is more pronounced for lower surface
temperatures at the heating line. The TKE profiles reveal
preferred regions of TKE growth that can be attributed
mainly to buoyancy or advection effects.
Moisture Content of Fine Forest Fuels and Fire Occurrence in Central Portugal
Authors: Viegas DX , Viegas MTSP , Ferreira AD
Published: October 2005

Moisture content of ten fine fuels frequent in
the forests of CentralPortugal and in other Mediterranean
areas was measured daily since 1986. Average monthly
results are presented for the period of 1987-1990.
Pinuspinaster sticks were used as a predictor of dead
fuel moisture content. A reasonable correlation was obtained with the moisture content of Pinus pinaster dead
needles and Eucalyptus globulus dead leaves. Two options of the MOISTURE module of BEHAVE system
were also tested to predict the daily minimum value of
fine dead fuel moisture content. Predicted values were
always lower than direct measurements, specially when
only meteorological data was used. A better agreement
was obtained when known moisture content of the previous day was introduced.
Using statistical data of oily fire occurrence in some
districts around the site where the tests were made, for the
same period of time, the probability of fire occurrence,
the average number of daily fires and the average area
burned each year was analysed as a function of dead pine
needles moisture content. Three distinct zones, around
and adjacent to the test site showed a very similar
behaviour.
When It's Hot, It's Hot... Or Maybe It's Not! (Surface Flaming May Not Portend Extensive Soil Heating)
Authors: Hartford RA , Frandsen WH
Published: October 2005

Fire effects on aplant community, soil, and air
are not apparent when judged only by surface fire intensity. The fire severity or fire impact can be described by
the temperatures reached within the forest floor and the
duration of heating experienced in the vegetation, forest
floor, and underlying mineral soil. Temporal distributions of temperatures illustrate heat flow in duff and
mineral soil in three instrumented plots: two with slash
fuel over moist duff and one with litter fuel over dry duff.
Fires in the two slash fuel plots produced substantial
flame lengths but minimal heating in the underlying
mineral soil. In contrast, smoldering combustion in the
dry duff plot produced long duration heating with nearly
complete duff consumption and lethal temperatures at the
mineral soil surface. Moisture content of duff and soil
were key variables for determining f i e impact on the
forest floor.
Mass and Energy Transfer Within and Between Burned and Unburned Savanna Environments
Authors: San José JJ
Published: October 2005

Energy fluesand transfer resistances in burned
and unburned savannas of the Orinoco Llanos were
comparatively evaluated using the energy balance approach. It was found that after burning, the atmospheric
transfer features of the savanna were changed as the net
flux of long wave radiation increased from 6.192 to
7.692 MJm2day-' and therefore less energy was available
at the surface. Net radiation in the burned and unburned
savannas was mainly dissipated as sensible heat (76-
74 percent) and even though the burned and unburned
savannas present constrasting surface properties, energy
partitioning was similar in both plots because the
relative greater aerodynamic resistance occurring at the
burned savanna was compensated by the strong temperature stratification under the bare soil conditions.
Thus, bouyancy generated turbulence in the burned
savanna provived a 3 times greater mixing as compared
to the roughness generated turbulence in the unburned
savanna. The micrometeorogical measurements at the
leading edge between the burned and unburned savannas
evidenced horizontal heat flux as advection ( 1.458
MJm-'day-') when the air moved from the smooth and hot
bare soil to the rougher and cooler vegetated surface.
Photosynthate Allocation Patterns Along a Fire-Induced Age Sequence in Two Shrub Species From the California Chaparral
Authors: Sparks SR , Oechel WC , Mauffette Y
Published: October 2005

In the prolonged absence of fire, shrubs of the California chaparral have sometimes been reported to demonstrate an increase in the proportion of standing dead biomass and a decrease in productivity (''senescence''). To investigate the possible physiological basis of this phenomenon, seasonal patterns of the allocation of 14C-labeled photosynthate were studied in leaves of two chaparral species, Adenostoma fasciculatum H. & A. and Ceanothus greggii var. perplexans (Trel.) Jeps., along a fire-induced age sequence. Harvested leaves labeled with 14C were analyzed for percent of 14C in storage, structural, metabolic, and defense compounds. No age-specific trends in photosynthate allocation were found except in the spring. During spring, when demands on photosynthate for growth were high, shrubs in older stands allocated a much lower proportion ot their photosynthate to storage compounds compared to shrubs in younger stands. Older shrubs are apparently less able to meet the concurrent demands of storage and growth during spring than younger shrubs. This observation is consistent with the notion of physiological senescence in older shrubs, and has implications for questions about the optimum length of the fire-free interval for stands managed with prescribed burning.
Microplot Sampling of Fire Behavior on Populus tremuloides Stands in North-Central Colorado
Authors: Smith JK , Laven RD , Omi PN
Published: October 2005

Fire behavior research has traditionally used whole burns as sampling units. Numerous burns were required to quantify relationships between pre-burn descriptors, fire behavior, and fire effects. Recent studies have used small plots within burns (called microplots) as the sampling units. This study measured pre-burn descriptors and fire behavior on 0.75-m2 microplots in two Populus tremuloides Michx. burns in north-central Colorado. Microplot estimates of woody fuels, spread rate, and area burned were comparable with measurements from whole burns. Two methods of estimating fire intensity on microplots produced inconsistent results. Juniperus communis L. patches burned more intensely and released more heat than herbaceous areas. Duff characteristics were the most useful pre-burn descriptors for predicting area burned, spread rate, flame length, and total heat release. Microplot sampling on two bums enabled us to relate variability in fire behavior to pre-burn characteristics and to obtain replicate estimates of these relationships.
Wildfire Impacts on Soil-Erosion and Hydrology in Wet Mediterranean Forest, Portugal
Authors: Shakesby RA , Coelho CDA , Ferreira AD , Terry JP , Walsh RPD
Published: October 2005

The Agueda Basin, north-central Portugal is comparatively wet (rainfall, 1600-1800 mm/yr) with frequent, relatively large storms in autumn and winter yet the summer drought is sufficiently long and consistent for frequent forest wildfires. This paper discusses wildfire impacts in such a wet Mediterranean environment on soil hydrophobicity, infiltration capacity, overland flow coefficients, soil loss, rainsplash detachment and small-scale ground level changes for Eucalyptus globulus and Pinus pinaster forest: (1) 0-2 years after fire ('new' burn); (2) 3-4 years after fire ('old' burn); and (3) 'mature' (or long unburnt) sites. For 'new' burn sites, rainsplash detachment rates are an order of magnitude and soil losses two orders of magnitude higher than for 'old' burn sites and both are two orders of magnitude higher than for 'mature' sites. Soils are hydrophobic in all three categories of sites, but infiltration capacities are lower at 'new' burn and 'old' burn than at 'mature' sites. Overland flow coefficients on long unburnt sites were low while on burnt sites they were high and tended to be higher for summer and autumn than for winter and spring, implying enhanced hydrophobicity under summer drought conditions, causing decreased infiltration capacity and increased overland flow. The distinctiveness of fire effects on soil erosion and hydrology in this wet Mediterranean environment and implications for post-fire management are discussed.
Byram Derivation of the Energy Criterion for Forest and Wildland Fires
Authors: Nelson RM
Published: October 2005

G.M. Byram's energy criterion for forest and wildland fires consists of two equations: one for computing the rate of flow of kinetic energy in the atmosphere due to the wind field (Pw), and one for estimating the rate of conversion of thermal energy to kinetic energy in the convection column (Pf). The derivation of the equations has remained unpublished since their introduction in 1959. Byram considered the dimensionless ratio of Pf to Pw an indicator of the vertical structure of convection over a fire and referred to the ratio as the convection number, Nc. In view of past and current interest in the behavior of large fires, Byram's derivation of the equations for Pw and Pc is presented along with a sketch and some additional wording for purposes of clarification. The assumptions and possible limitations in Byram's analysis are discussed.
Thinning Young Loblolly Pine Stands With Fire
Authors: Wade DD
Published: October 2005

The relationship between fire-caused stem girdling and groundline diameter (GLD) in loblolly pine (Pinus taeda L.) was determined. Results of 10 experimental prescribed bums conducted across a wide range of ambient temperature conditions during both the dormant and growing season demonstrate that low-intensity backing fires (< 346 KW/m) are an effective tool to eliminate loblolly pines less than 3.8 cm (1.5 in.) GLD. Wide differences in ambient temperature at time of burning did not affect stem kill of unscorched trees in this study. Virtually all fire-caused mortality took place within four months postburn. A predictive model that explained 92% of the variation in mortality was developed to facilitate the use of fire to thin young, overcrowded loblolly pine stands in the southeastern United States. Use of this model in conjunction with a preburn stand survey allows estimation of the number and distribution of survivors prior to ignition.
The Speed of a Fire Front and Its Dependence on Wind-Speed
Authors: Beer T
Published: October 2005

The results of a number of laboratory tests of wind-driven fires indicate the existence of a characteristic wind speed, U'. The form of the fire spread (V) as a function of mid-flame wind speed (U) differs above and below this characteristic speed. The scatter in field data is so great that it is difficult to confirm this result for field data. However, expressions of the form: V/V0 -1 = α(U/U')0.5 U/U' < 1 and V/V0 -1 = α(U/U')3 U/U' > 1 with U' = 2.5 m s-1 perform in a similar manner to existing models. For many fuel types α = 15. A difficulty with existing fire spread models is the measurement and definition of V0, the no-wind rate of spread. It can hardly ever be measured in the field and has to be inferred from analytical formulae, or by extrapolating measured data. The value of a depends on the method used estimate V0.
Seed Germination in the Fynbos Fire Ephemeral, Syncarpha vestita (L) B-Nord Is Promoted by Smoke, Aqueous Extracts of Smoke and Charred Wood Derived From Burning the Ericoid-Leaved Shrub, Passerina vulgaris Thoday
Authors: Brown NAC
Published: October 2005

Periodic fires are a natural phenomenon in fynbos, which is the dominant vegetation type in the Cape floristic region. Fire-stimulated germination has been reported for a number of fynbos species. The promotion of seed germination in the fynbos fire ephemeral, Syncarpha vestita (L.) B.Nord. (Asteraceae), by plant-derived smoke and aqueous smoke extracts derived from stem and leaf material of the ericoid-leaved shrub, Passerina vulgaris Thoday (Thymelaeaceae), reported by Brown (1993), was confirmed in this study. In addition, for the first time, aqueous extracts of charred wood alone have been shown to promote seed germination in a species of fynbos. The fact that a number of derivatives of P. vulgaris plant material all showed germination-promotion activity poses the question as to whether there is one bioactive substance or whether the activity of each derivative depends on a different substance.