bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water ascent in tall trees: does evolution of land plants rely on a highly metastable state?
Authors: Zimmermann Ulrich , Schneider Heike , Wegner Lars H. , Haase Axel 
Published: May 2004

SummaryThe Cohesion Theory considers plant xylem as a ‘vulnerable pipeline’ isolated from the osmotically connected tissue cells, phloem and mycorrhizas living in symbiosis with plant roots. It is believed that water is pulled exclusively by transpiration‐induced negative pressure gradients of several megapascals through continuous water columns from the roots to the foliage. Water under such negative pressures is extremely unstable, particularly given the hydrophobicity of the inner xylem walls and sap composition (lipids, proteins, mucopolysaccharides, etc.) that prevents the development of stable negative pressures larger than about −1 MPa. However, many plant physiologists still view the Cohesion Theory as the absolute and universal truth because clever wording from the proponents of this theory has concealed the recent breakdown of the Scholander pressure bomb (and other indirect methods) as qualified tools for measuring negative pressures in transpiring plants. Here we show that the arguments of the proponents of the Cohesion Theory are completely misleading. We further present an enormous bulk of evidence supporting the view that – depending on the species and ecophysiological context – many other forces, additional to low tensions, can be involved in water ascent and that water can be lifted by a series of watergates (like ships in staircase locks).ContentsI.Introduction576II.Can water sustain negative pressures?577III.Negative xylem pressures of several megapascals: fact or mystery?579IV.The continuity of the xylem water columns: fact or hypothesis?588V.The ‘Multi‐Force’ or ‘Watergate’ Theory590VI.Conclusions604Acknowledgements605References605Appendix 1612Appendix 2613
Inferring nocturnal surface fluxes from vertical profiles of scalars in an Amazon pasture
Authors: Acevedo Otávio C. , Moraes Osvaldo L. L. , Da Silva Rodrigo , Fitzjarrald David R. , Sakai Ricardo K. , Staebler Ralf M. , Czikowsky Matthew J. 
Published: May 2004

AbstractEcosystem carbon budgets depend on there being good representative surface flux observations for all land use types during the entire diurnal cycle. In calm conditions that often occur at night, especially in areas of small roughness (such as pastures), ecosystem respiration rate is poorly measured using the eddy covariance (EC) technique. Nocturnal vertical profiles of temperature, humidity and winds were observed using tethered balloon soundings in a pasture in the eastern Amazon during two campaigns in 2001. The site is characterized by very weak winds at night, so that there is insufficient turbulence for the EC technique to determine fluxes accurately. To compensate, the time evolution of the profiles is used to determine surface fluxes at early morning and these are compared with those observed by EC at a nearby micrometeorological tower. The nocturnal boundary layer thickness h is determined as the height to which the surface fluxes must converge so that energy budget closure is achieved. The estimated values range from 30 m, around 22:00 hours LST, to more than 100 m just before dawn. These are in good agreement with the observed thickness of a frequently observed fog layer during the middle of the night. During the early portion of the night, when the accumulation layer is shallow, there is appreciable decrease of dCO2/dt with height. On calm nights, CO2 accumulation rate is larger near the surface than at higher levels. On windier nights, this accumulation rate is vertically uniform. Hence, extrapolation of tower profiles for estimating fluxes must be done carefully. Although uncertainties remain large, an alternate approach to the EC method is described for measuring nighttime surface CO2 fluxes under stable atmospheric conditions.
Variation in potential for isoprene emissions among Neotropical forest sites
Authors: Harley Peter , Vasconcellos Pérola , Vierling Lee , Pinheiro Carlos Cleomir de S. , Greenberg James , Guenther Alex , Klinger Lee , Almeida Samuel Soares de , Neill David , Baker Tim , Phillips Oliver , Malhi Yadvinder 
Published: May 2004

AbstractAs part of the Large Scale Biosphere–Atmosphere Experiment in Amazônia (LBA), we have developed a bottom‐up approach for estimating canopy‐scale fluxes of isoprene. Estimating isoprene fluxes for a given forest ecosystem requires knowledge of foliar biomass, segregated by species, and the isoprene emission characteristics of the individual tree species comprising the forest. In this study, approximately 38% of 125 tree species examined at six sites in the Brazilian Amazon emitted isoprene. Given logistical difficulties and extremely high species diversity, it was possible to screen only a small percentage of tree species, and we propose a protocol for estimating the emission capacity of unmeasured taxa using a taxonomic approach, in which we assign to an unmeasured genus a value based on the percentage of genera within its plant family which have been shown to emit isoprene.Combining this information with data obtained from 14 tree censuses at four Neotropical forest sites, we have estimated the percentage of isoprene‐emitting biomass at each site. The relative contribution of each genus of tree is estimated as the basal area of all trees of that genus divided by the total basal area of the plot. Using this technique, the percentage of isoprene‐emitting biomass varied from 20% to 42% (mean=31%; SD=8%).Responses of isoprene emission to varying light and temperature, measured on a sun‐adapted leaf of mango (Mangifera indica L.), suggest that existing algorithms developed for temperate species are adequate for tropical species as well. Incorporating these algorithms, estimates of isoprene‐emitting biomass, isoprene emission capacity, and site foliar biomass into a canopy flux model, canopy‐scale fluxes of isoprene were predicted and compared with the above‐canopy fluxes measured at two sites. Our bottom‐up approach overestimates fluxes by about 50%, but variations in measured fluxes between the two sites are largely explained by observed variation in the amount of isoprene‐emitting biomass.
Soil CO2 efflux in a tropical forest in the central Amazon
Authors: Doff sotta Eleneide , Meir Patrick , Malhi Yadvinder , Donato nobre Antonio , Hodnett Martin , Grace John 
Published: May 2004

AbstractThis study investigated the spatial and temporal variation in soil carbon dioxide (CO2) efflux and its relationship with soil temperature, soil moisture and rainfall in a forest near Manaus, Amazonas, Brazil. The mean rate of efflux was 6.45±0.25 SE μmol CO2 m−2s−1 at 25.6±0.22 SE°C (5 cm depth) ranging from 4.35 to 9.76 μmol CO2 m−2s−1; diel changes in efflux were correlated with soil temperature (r2=0.60). However, the efflux response to the diel cycle in temperature was not always a clear exponential function. During period of low soil water content, temperature in deeper layers had a better relationship with CO2 efflux than with the temperature nearer the soil surface. Soil water content may limit CO2 production during the drying‐down period that appeared to be an important factor controlling the efflux rate (r2=0.39). On the other hand, during the rewetting period microbial activity may be the main controlling factor, which may quickly induce very high rates of efflux. The CO2 flux chamber was adapted to mimic the effects of rainfall on soil CO2 efflux and the results showed that efflux rates reduced 30% immediately after a rainfall event. Measurements of the CO2 concentration gradient in the soil profile showed a buildup in the concentration of CO2 after rain on the top soil. This higher CO2 concentration developed shortly after rainfall when the soil pores in the upper layers were filled with water, which created a barrier for gas exchange between the soil and the atmosphere.
Coarse woody debris in undisturbed and logged forests in the eastern Brazilian Amazon
Authors: Keller Michael , Palace Michael , Asner Gregory P. , Pereira Rodrigo , Silva José Natalino M. 
Published: May 2004

AbstractCoarse woody debris (CWD) is an important component of the carbon cycle in tropical forests. We measured the volume and density of fallen CWD at two sites, Cauaxi and Tapajós in the Eastern Amazon. At both sites we studied undisturbed forests (UFs) and logged forests 1 year after harvest. Conventional logging (CL) and reduced impact logging (RIL) were used for management on areas where the geometric volumes of logs harvested was about 25–30 m3 ha−1. Density for five classes of fallen CWD for large material (>10 cm diameter) ranged from 0.71 to 0.28 Mg m−3 depending upon the degree of decomposition. Density of wood within large fallen logs varied with position relative to the ground and with distance from the center of the log. Densities for materials with diameters from 2 to 5 and 5 to 10 cm were 0.36 and 0.45 Mg m−3, respectively. The average mass (±SE) of fallen CWD at Cauaxi was 55.2 (4.7), 74.7 (0.6), and 107.8 (10.5) Mg ha−1 for duplicate UF, RIL, and CL sites, respectively. At Tapajós, the average mass of fallen CWD was 50.7 (1.1) Mg ha−1 for UF and 76.2 (10.2) Mg ha−1 for RIL for duplicate sites compared with 282 Mg ha−1 for live aboveground biomass. Small‐ and medium‐sized material (<10 cm dia.) accounted for 8–18% of the total fallen CWD mass. The large amount of fallen CWD at these UF sites relative to standing aboveground biomass suggests either that the forests have recently been subjected to a pulse of high mortality or that they normally suffer a high mortality rate in the range of 0.03 per year. Accounting for background CWD in UF, CL management produced 2.7 times as much CWD as RIL management. Excess CWD at logging sites would generate a substantial CO2 emission given the high rates of decay in moist tropical forests.
Land‐use change effects on local energy, water, and carbon balances in an Amazonian agricultural field
Authors: Sakai Ricardo K. , Fitzjarrald David R. , Moraes Osvaldo L.L. , Staebler Ralf M. , Acevedo Otávio C. , Czikowsky Matthew J. , Silva Rodrigo da , Brait Eleazar , Miranda Valdelirio 
Published: May 2004

AbstractTo study how changing agricultural practices in the eastern Amazon affect carbon, heat and water exchanges, a 20 m tower was installed in a field in August 2000. Measurements include turbulent fluxes (momentum, heat, water vapor, and CO2) using the eddy covariance (EC) approach, soil heat flux, wind, and scalar profiles (T, q, and CO2), soil moisture content, terrestrial, total solar radiation, and photosynthetically active radiation (PAR, 400–700 nm). At the beginning of the measurements, in September 2000, the field was a pasture. On November 2001, the pasture was burned, plowed, and planted in upland (nonirrigated) rice.Calm nights were the norm in this site. Anomalously low values of net ecosystem exchange (NEE) were found using the EC method, even when the common criterion u*<0.2 m s−1 was used to identify and exclude poor performance nights. We observed more plausible values of NEE using criterion u*<0.08 m s−1, indicating that the criterion must be revised downward for flow over surfaces smoother than forests. However, even using the lower threshold, u* was lower than this limit for 82% of nights, and this led to nocturnal respiration underestimates. We compensate for this difficulty by estimating the respiration rate using the nocturnal boundary layer budget method.Land‐use change from pasture to rice cultivation strongly affected both diurnal rates of turbulent exchange but also the pattern of seasonal variation. Seasonal wet and dry season differences in vegetation state were clearly detected in the albedo and PAR‐albedo. These reflectivity changes were accompanied by modified net radiative flux, turbulent heat flux and evaporation rates. The highest evaporation rate was observed during the rice crop, when the field had total evaporation approximately half the precipitation input, less than that of the surrounding forest. Effects of the land‐cover changes were also detected in the carbon budget. For the pasture, the maximum CO2 uptake occurred in May, appreciably delayed from the start of the rainy season. After the field was plowed and the soil was exposed and there was efflux of CO2 to the atmosphere day and night for an extended period. Highest values of carbon uptake occurred during the rice plantation. Although the upland rice took up carbon at double the rate of the pasture that it replaced, the field was left fallow for much of the year, during the dry season.
Clinically important deep vein thrombosis in the intensive care unit: a survey of intensivists
Authors: Cook Deborah , Meade Maureen , Guyatt Gordon , Griffith Lauren , Granton John , Geerts William , Crowther Mark ,   the Canadian Critical Care Trials Group
Published: May 2004

Abstract
Introduction
Outside the intensive care unit (ICU), clinically important deep vein thrombosis (DVT) is usually defined as a symptomatic event that leads to objective radiologic confirmation and subsequent treatment. The objective of the present survey is to identify the patient factors and radiologic features of lower limb DVT that intensivists consider more or less likely to make a DVT clinically important in ICU patients.

Methods
Our definition of clinically important DVT was a DVT likely to result in short-term or long-term morbidity or mortality if left untreated, as opposed to a DVT that is unlikely to have important consequences. We asked respondents to indicate the likelihood that patient factors and ultrasonographic features make a DVT clinically important using a five-point scale (from 1 = much less likely to 5 = much more likely).

Results
Of the 71 Canadian intensivists who responded, 70 (99%) rated three patient factors as most likely to make a DVT clinically important: clinical suspicion of pulmonary embolism (mean score 4.6), acute or chronic cardiopulmonary morbidity that might limit a patient's ability to tolerate pulmonary embolism (score 4.5), and leg symptoms (score 4.2). Of the ultrasound features, proximal (score 4.7), large (score 4.2), and totally occlusive (score 3.9) thrombi were considered the three most important.

Conclusion
When labeling a DVT as clinically important, intensivists rely on different patient specific factors and thrombus characteristics than are used to assess the clinical importance of DVT outside the ICU. The clinical importance of DVT is influenced by unique factors such as cardiopulmonary reserve among mechanically ventilated patients.
Age Is a Risk Factor for Chemotherapy-Induced Hepatopathy With Vincristine, Dactinomycin, and Cyclophosphamide
Authors: Arndt C. , Hawkins D. , Anderson J.R. , Breitfeld P. , Womer R. , Meyer W. 
Published: May 2004

Purpose To evaluate the spectrum of and determine the risk factors for the development of liver toxicity (hepatopathy) after therapy with vincristine, dactinomycin, and cyclophosphamide (VAC) for rhabdomyosarcoma in children and adolescents. Patients and Methods We prospectively captured all events of hepatopathy occurring on the ongoing Children's Oncology Group intermediate risk protocol, D9803, for children with rhabdomyosarcoma. Patients enrolled onto this trial were randomly assigned to receive either VAC alone or VAC alternating with vincristine, topotecan, and cyclophosphamide. In addition, we reviewed the toxicity database and requested additional information for all patients with elevated bilirubin or transaminase levels. Risk factors were analyzed. Results Of 339 patients enrolled through August 2002, 18 developed hepatopathy. All events were captured by mandated toxicity reporting and filing of MedWatch forms, with no additional cases found after the additional search of the database. Four children died after developing this toxicity. All cases occurred after cycles of VAC (n = 16) or vincristine and cyclophosphamide with concomitant abdominal radiotherapy (n = 2). The onset of hepatopathy was 5 to 16 days from the start of a treatment cycle. For the 89 patients under 36 months of age, the risk of hepatopathy was 15%, with two deaths. For the 239 children 3 years of age or older, the risk for hepatopathy was 4%, with two deaths. Conclusion The greatest risk factor for development of hepatopathy after VAC therapy was age. Dose modifications for younger children receiving VAC therapy are recommended.
Major Depression, Adjustment Disorders, and Post-Traumatic Stress Disorder in Terminally Ill Cancer Patients: Associated and Predictive Factors
Authors: Akechi Tatsuo , Okuyama Toru , Sugawara Yuriko , Nakano Tomohito , Shima Yasuo , Uchitomi Yosuke 
Published: May 2004

PurposeFew studies have been conducted to elucidate the psychological distress of terminally ill cancer patients. This study attempted to determine the prevalence of adjustment disorders (AD), major depression (MD), and post-traumatic stress disorder (PTSD) among terminally ill cancer patients, to identify factors that contribute to them, and to determine how they change longitudinally.Patients and MethodsConsecutive terminally ill cancer patients were recruited. Patients were assessed for psychiatric disorders by structured clinical interview twice: once at the time of their registration with a palliative care unit (baseline), and again at the time of their palliative care unit admission (follow-up). Possible contributed biomedical and psychosocial factors were evaluated.ResultsThe proportions of patients diagnosed with AD, MD, and PTSD at baseline (n = 209) were 16.3%, 6.7%, and 0% respectively, whereas at follow-up (n = 85), 10.6% were diagnosed with AD and 11.8% with MD. Lower performance status, concern about being a burden to others, and lower satisfaction with social support were significantly associated with AD/MD at baseline. There were changes in the diagnosis of AD and MD in 30.6% of the patients. Only the Hospital Anxiety and Depression Scale at the baseline was significantly predictive of AD/MD at follow-up.ConclusionThe factors underlying psychological distress are multifactorial. Early intervention to treat subclinical anxiety and depression may prevent subsequent psychological distress.
Low Molecular Weight Heparin, Therapy With Dalteparin, and Survival in Advanced Cancer: The Fragmin Advanced Malignancy Outcome Study (FAMOUS)
Authors: Kakkar Ajay K. , Levine Mark N. , Kadziola Zbigniew , Lemoine Nicholas R. , Low Vanessa , Patel Heman K. , Rustin Gordon , Thomas Michael , Quigley Mary , Williamson Robin C.N. 
Published: May 2004

Purpose In experimental systems, interference with coagulation can affect tumor biology. Furthermore, it has been suggested that low molecular weight heparin therapy may prolong survival in patients with cancer. The primary aim of this study was to assess survival at 1 year of patients with advanced cancer. Patients and Methods Patients with advanced malignancy (N = 385) were randomly assigned to receive either a once-daily subcutaneous injection of dalteparin (5,000 IU), a low molecular weight heparin, or placebo for 1 year. Results The Kaplan-Meier survival estimates at 1, 2, and 3 years after randomization for patients receiving dalteparin were 46%, 27%, and 21%, respectively, compared with 41%, 18%, and 12%, respectively, for patients receiving placebo (P = .19). In an analysis not specified a priori, survival was examined in a subgroup of patients (dalteparin, n = 55; and placebo, n = 47) who had a better prognosis and who were alive 17 months after randomization. In these patients, Kaplan-Meier survival estimates at 2 and 3 years from randomization were significantly improved for patients receiving dalteparin versus placebo (78% v 55% and 60% v 36%, respectively, P = .03). The rates of symptomatic venous thromboembolism were 2.4% and 3.3% for dalteparin and placebo, respectively, with bleeding rates of 4.7% and 2.7%, respectively. Conclusion Dalteparin administration did not significantly improve 1-year survival rates in patients with advanced malignancy. However, the observed improved survival in a subgroup of patients with a better prognosis suggests a potential modifying effect of dalteparin on tumor biology.
Prognostic Indicators and Survival in Patients With Stage IIIB Inflammatory Breast Carcinoma After Dose-Intense Chemotherapy
Authors: Somlo George , Frankel Paul , Chow Warren , Leong Lucille , Margolin Kim , Morgan Robert , Shibata Stephen , Chu Peiguo , Forman Stephen , Lim Dean , Twardowski Przemyslaw , Weitzel Jeffrey , Alvarnas Joseph , Kogut Neil , Schriber Jeffrey , Fermin Eleanor , Yen Yun , Damon Lloyd , Doroshow James H. 
Published: May 2004

Purpose To improve treatment outcome for patients presenting with inflammatory breast cancer (IBC), we have sequentially developed and tested single and tandem dose-intense chemotherapy regimens (DICT). Tumor- and treatment-related factors were analyzed to generate a prognostic model. Patients and Methods Between May 1989 and April 2002, 120 patients received conventional-dose chemotherapy, surgery, and sequentially developed single- or tandem-cycle DICT. Disease- and treatment-specific features were subjected to univariate and multivariate analysis to correlate with outcome. Results At a median follow-up of 61 months (range, 21 to 161 months), estimated 5-year relapse-free survival (RFS) and overall survival (OS) were 44% (95% CI, 34% to 53%) and 64% (95% CI, 55% to 73%), respectively. In an age-adjusted multivariate analysis, RFS was better in patients with estrogen receptor (ER)/progesterone receptor (PR)–positive tumors (P = .002), for patients with fewer than four involved axillary nodes before DICT (P = .01), and in patients treated with radiation therapy (P = .001) and tandem DICT (P = .049). OS was improved in patients with ER/PR-positive tumors (P = .002), in those with fewer than four involved axillary nodes before DICT (P = .03), and in patients treated with radiation therapy (P = .002). Conclusion This retrospective analysis suggests that either single or tandem DICT can be administered safely and may benefit selected patients with stage IIIB IBC. Those with receptor-negative IBC and with four or more involved axillary nodes before DICT need improved neoadjuvant and postadjuvant intensification therapy. A prospective randomized trial of single versus tandem DICT would be required to confirm the potential benefit of tandem DICT in the setting of IBC.