bluuebunny/crossref_metadata_2025_split huggingface dataset:
Are old forests underestimated as global carbon sinks?
Authors: Carey Eileen V. , Sala Anna , Keane Robert , Callaway Ragan M. 
Published: March 2003

SummaryOld forests are important carbon pools, but are thought to be insignificant as current atmospheric carbon sinks. This perception is based on the assumption that changes in productivity with age in complex, multiaged, multispecies natural forests can be modelled simply as scaled‐up versions of individual trees or even‐aged stands. This assumption was tested by measuring the net primary productivity (NPP) of natural subalpine forests in the Northern Rocky Mountains, where NPP is from 50% to 100% higher than predicted by a model of an even‐age forest composed of a single species. If process‐based terrestrial carbon models underestimate NPP by 50% in just one quarter of the temperate coniferous forests throughout the world, then global NPP is being underestimated by 145 Tg of carbon annually. This is equivalent to 4.3–7.6% of the missing atmospheric carbon sink. These results emphasize the need to account for multiple‐aged, species‐diverse, mature forests in models of terrestrial carbon dynamics to approximate the global carbon budget.
Microbial processes and temperature in Chesapeake Bay: current relationships and potential impacts of regional warming
Authors: Lomas Michael W. , Glibert Patricia M. , Shiah Fuh‐Kwo , Smith Erik M. 
Published: March 2003

AbstractThe importance of temperature in regulating physiological processes is without question; however, the interpretation of the relationship between temperature and ecological data is much more complicated. Consequently, it is difficult to decide how the nature of the temperature response terms should be included in models used to predict responses of microbial processes to increasing regional temperature. This analysis compiles several years of data from a research programme conducted in Chesapeake Bay, in an effort to examine how individual microbial processes − as well as the balance between autotrophy and heterotrophy − have responded to temperature, and to predict changes in microbial trophic state based on realistic increases in global temperature. The upper boundary on all of the pelagic microbial rate processes that were measured could be described remarkably well as a linear function of temperature, although there was substantial scatter in the data. Pelagic microbial rate processes (e.g. phytoplankton production, respiration, bacterial productivity) showed a remarkably constrained range of Q10 values from 1.7 to 3.4. The one notable exception to this was nitrogen uptake in the North and Mid Bay, which exhibited Q10 values < 1.0. Proxies for phytoplankton biomass (e.g. chlorophyll) were largely independent of temperature while bacterial abundance was significantly related to temperature and was found to have a Q10 of 1.88.    Using these individual temperature responses, the balance of autotrophy and heterotrophy was assessed by calculating the community photosynthesis to respiration (P:R), NH4+ uptake to regeneration (U:R) and phytoplankton to bacterial productivity (PP:BP) ratios for current conditions (all ratios) and for a 2 and 5 °C temperature increase (NH4+ U:R excluded). The NH4+ U:R ratio stayed remarkable constant at ∼1 over the entire temperature range supporting the importance of regenerative processes to nitrogen availability even during periods of heavy allochthonous inputs. These elevated temperature calculations for P:R and PP:BP suggest that the magnitude of autotrophic production during the spring bloom may decrease with increased regional temperature and, as a consequence, the Chesapeake Bay might become net heterotrophic on an annual timescale. These calculations should be considered with caution, but nonetheless demonstrate that the impact of increasing temperature on the balance of autotrophic and heterotrophic processes needs to be researched further.
Carbon emission and sequestration by agricultural land use: a model study for Europe
Authors: Vleeshouwers L. M. , Verhagen A. 
Published: March 2003

AbstractA model was developed to calculate carbon fluxes from agricultural soils. The model includes the effects of crop (species, yield and rotation), climate (temperature, rainfall and evapotranspiration) and soil (carbon content and water retention capacity) on the carbon budget of agricultural land. The changes in quality of crop residues and organic material as a result of changes in CO2 concentration and changed management were not considered in this model. The model was parameterized for several arable crops and grassland. Data from agricultural, meteorological, soil, and land use databases were input to the model, and the model was used to evaluate the effects of different carbon dioxide mitigation measures on soil organic carbon in agricultural areas in Europe. Average carbon fluxes under the business as usual scenario in the 2008–2012 commitment period were estimated at 0.52 tC ha−1 y−1 in grassland and −0.84 tC ha−1 y−1 in arable land. Conversion of arable land to grassland yielded a flux of 1.44 tC ha−1 y−1. Farm management related activities aiming at carbon sequestration ranged from 0.15 tC ha−1 y−1 for the incorporating of straw to 1.50 tC ha−1 y−1 for the application of farmyard manure. Reduced tillage yields a positive flux of 0.25 tC ha−1 y−1. The indirect effect associated with climate was an order of magnitude lower. A temperature rise of 1 °C resulted in a −0.05 tC ha−1 y−1 change whereas the rising CO2 concentrations gave a 0.01 tC ha−1 y−1 change. Estimates are rendered on a 0.5 × 0.5° grid for the commitment period 2008–2012. The study reveals considerable regional differences in the effectiveness of carbon dioxide abatement measures, resulting from the interaction between crop, soil and climate. Besides, there are substantial differences between the spatial patterns of carbon fluxes that result from different measures.
Environmental controls on net ecosystem‐level carbon exchange and productivity in a Central American tropical wet forest
Authors: LOESCHER H. W. , OBERBAUER S. F. , GHOLZ H. L. , CLARK D. B. 
Published: March 2003

AbstractDifficulty in balancing the global carbon budget has lead to increased attention on tropical forests, which have been estimated to account for up to one third of global gross primary production. Whether tropical forests are sources, sinks, or neutral with respect to their carbon balance with the atmosphere remains unclear. To address this issue, estimates of net ecosystem exchange of carbon (NEE) were made for 3 years (1998–2000) using the eddy‐covariance technique in a tropical wet forest in Costa Rica. Measurements were made from a 42 m tower centred in an old‐growth forest. Under unstable conditions, the measurement height was at least twice the estimated zeroplane height from the ground. The canopy at the site is extremely rough; under unstable conditions the median aerodynamic roughness length ranged from 2.4 to 3.6 m. No relationship between NEE and friction velocity (u*) was found using all of the 30‐min averages. However, there was a linear relationship between the nighttime NEE and averaged u* (R2 = 0.98). The diurnal pattern of flux was similar to that found in other tropical forests, with mean daytime NEE ca. − 18 μmol CO2 m−2 s−1 and mean nighttime NEE 4.6 μmol CO2 m−2 s−1. However, because ∼ 80% of the nighttime data in this forest were collected during low u* conditions (< 0.2 m s−1), nighttime NEE was likely underestimated. Using an alternative analysis, mean nighttime NEE increased to 7.05 μmol CO2 m−2 s−1. There were interannual differences in NEE, but seasonal differences were not apparent. Irradiance accounted for ∼ 51% of the variation in the daytime fluxes, with temperature and vapour pressure deficit together accounting for another ∼ 20%. Light compensation points ranged from 100 to 207 μmol PPFD m−2 s−1. No was relationship was found between 30‐min nighttime NEE and tower‐top air temperature. A weak relationship was found between hourly nighttime NEE and canopy air temperature using data averaged hourly over the entire sampling period (Q10 = 1.79, R2 = 0.17). The contribution of below‐sensor storage was fairly constant from day to day. Our data indicate that this forest was a slight carbon source in 1998 (0.05 to −1.33 t C ha−1 yr−1), a moderate sink in 1999 (−1.53 to −3.14 t C ha−1 yr−1), and a strong sink in 2000 (−5.97 to −7.92 t C ha−1 yr−1). This trend is interpreted as relating to the dissipation of warm‐phase El Niño effects over the course of this study.
Variations in the dietary cation–anion difference and the acid–base balance of dairy cows on a pasture‐based diet in south‐eastern Australia
Authors: Roche  , Dalley  , Moate  , Grainger  , Hannah  , O’Mara  , Rath  
Published: March 2003

The variation in the dietary cation–anion difference (DCAD) and the urinary pH of dairy cows was examined over the year 1996–97 in Victoria, south‐eastern Australia. Mineral concentrations in the pasture and dairy cow milk production were also examined. Three farmlets (A, B and C) under different feeding and management systems were used for the purpose of the study. Feeding management was based on grazed grass with stocking rates of 1·4, 2·5 and 4·7 cows ha–1 for farmlets A, B and C respectively. Cows on farmlets B and C received more supplementary feed than those on the A farmlet.The urine of the cows in each herd was sampled for pH twice monthly, after morning milking. A sample of the feed on offer the previous day was collected and analysed for crude protein, in vitro dry‐matter digestibility and macrominerals. Milk yields were recorded on the same day as urine sampling and weather data for the previous day were also collected.Pasture cation–anion difference was not greatly influenced by stocking rate or associated management practices, although mineral concentrations in pasture did vary. Urine pH was unaffected by changes in climate, management strategies (e.g. stocking rate), season and stage of lactation. Moreover, urine pH was also unaffected by changes in DCAD until the DCAD declined below approximately +15 mequiv. 100 g–1 for two consecutive sampling periods.It is concluded that when this threshold for DCAD (+15 mequiv. 100 g–1) is breached, even in late lactation, a decrease in urine pH occurs. In south‐eastern Australia, the DCAD offered to non‐lactating cows in the last 2 weeks of pregnancy, in spring‐calving herds, on a pasture‐based diet is nearly always above that regarded as optimum in other feeding systems.
A comparison of three methods for measuring the vertical distribution of herbage mass in grassland
Authors: Barthram  , Elston  , Bolton  
Published: March 2003

Three stratified clip methods for the estimation of herbage mass and its vertical distribution in grass swards were compared. The first method used a herbage‐gripping device, which held a sample from a 2 × 9 cm area while it was harvested and cut into layers in the field. For the other two methods, turfs of herbage were dug and brought into the laboratory where areas defined by 10 × 10 cm or 2 × 9 cm quadrats were cut into layers. For the comparisons, two operators collected independent samples from a sward shortly before it was cut for silage, a sward grazed by cattle and a sward grazed by sheep.The total mass of herbage dry matter collected depended on the method used, with the herbage‐gripping device producing greater estimates than the turf quadrats in two of the swards. The different methods produced similar estimates of the vertical distribution of mass. The larger quadrat usually produced the least variable results, while the herbage‐gripping device collected samples most quickly. There were also small differences between the estimates produced by different operators. It was concluded that because the herbage‐gripping device was the most cost‐effective it would often be the most appropriate method to use. However, when a higher level of precision per quadrat is required the large quadrat, following turf collection, would be more appropriate.
Endometrial sampling: does combining scraping with suction using the Accurette® device improve efficacy?
Authors: Kovacs Gabor , Hocking Glenn R. , Barnett Malcolm C. , V.T. Clark Jason 
Published: March 2003

ObjectiveTo assess the efficacy of the combination of scraping and suction (using Accurette®), compared with conventional curettage, in a pilot study.DesignProspective study with Accurette sampling preceding conventional curettage.SettingDay surgery unit of a teaching hospital.SubjectsWomen presenting for dilatation and curettage for abnormal bleeding.InterventionAccurette sampling carried out under anaesthetic just prior to curettage. The same pathologist reported on all specimens independently, without correlating specimen identities.Main outcome measuresQuality of the samples for histological investigation and comparison of reporting.ResultsAccurette was adequate except in the presence of polyps.ConclusionEndometrial sampling is a useful investigation for abnormal vaginal bleeding.
Preoperative evaluation of myometrial invasion in endometrial carcinoma by magnetic resonance imaging (MRI) and hysteroscopy: diagnostic efficacy of MRI combined with hysteroscopy
Authors: Shen Hong , Iha Tadashi , Higashi Masahiro , Kanazawa Koji 
Published: March 2003

ObjectiveTo evaluate the preoperative diagnostic usefulness of magnetic resonance imaging (MRI) combined with hysteroscopy, for the assessment of myometrial invasion in endometrial carcinoma.DesignProspective observational study.SettingDepartment of Obstetrics and Gynaecology, The Ryukyu University Hospital, Okinawa, Japan.Subjects73 patients with untreated endometrial carcinoma.InterventionsThe findings of myometrial tumour invasion preoperatively observed by MRI and hysteroscopy were compared with the histopathological findings from surgical specimens.Main outcome measuresThe sensitivity and specificity of MRI combined with hysteroscopy in diagnosing myometrial tumour invasion.ResultsIn diagnosing myometrial tumour invasion (absence or presence of myometrial invasion), the sensitivities and specificities were 82.0% and 100% in MRI, 80.0% and 95.7% in hysteroscopy, and 92.0% and 95.7% in MRI combined with hysteroscopy. The sensitivity in MRI combined with hysteroscopy was significantly higher, with a false‐negative rate of only 8.0%, than that of the other two methods (P = 0.025; P = 0.014). The differences in specificity were not statistically significant among these three methods (P > 0.05). MRI had a 87.8% accuracy in assessing the depth of myometrial invasion.ConclusionThese results indicate that MRI combined with hysteroscopy is an excellent diagnostic approach, superior to MRI or hysteroscopy alone, for the evaluation of myometrial tumour invasion, because MRI and hysteroscopy combined can compensate for the disadvantage or defect in each diagnostic procedure.
Abdominal hysterectomy: a comparison between the use of surgical staples and conventional sutures for the major pedicles
Authors: Krins Anthony , Kovacs Gabor 
Published: March 2003

ObjectiveTo compare the progress of patients undergoing abdominal hysterectomy using either surgical staples or conventional sutures for the ovarian and uterine pedicles.DesignA prospective randomized controlled study.SettingA teaching hospital gynaecology unit.Subjects24 women presenting for abdominal hysterectomy.InterventionsRoutine abdominal hysterectomy was undertaken. Uterine and ovarian pedicles were either ligated conventionally or secured by surgical staples.Main outcome measuresThese were: duration of operation, blood loss, length of hospital stay and recovery parameters.ResultsThere were no difficulties in applying the staples in this pilot study and there was no difference in the outcomes between the two methods.ConclusionsAlthough the use of surgical staples is an attractive principle, this pilot study could not demonstrate an advantage to justify the cost. Further evaluation may be indicated.
Ultrasonographic and hysteroscopic follow up after transcervical resection of the endometrium
Authors: Mints Miriam , Almström Harald , Rylander Eva , Rådestad Arne 
Published: March 2003

ObjectiveLong‐term follow‐up of women who have undergone transcervical resection of the endometrium (TCRE), and evaluation of the uterine endometrium and cavity in these women.DesignTransvaginal ultrasound examination (TVS) with hydrosonography and hysteroscopy, including biopsies, was carried out in 61 women, 19–67 months (mean 40 months) after transcervical endometrial resection.ResultsThe age range of the women was 37–58 years (mean 48 years). Of 61 women, 67% had amenorrhoea or hypomenorrhoea, 28% had withdrawal bleeding of normal amounts and three women suffered from polymenorrhoea. Of 40 women with dysmenorrhoea before treatment, 18 still had cyclic pain afterwards. In three women, dysmenorrhoea developed postoperatively. At ultrasound examination, an echo from the uterine cavity was found in 95% of the women and an echo of 5 mm or more was seen in 22%. Crypts and occlusions were present in 19% and synechiae in 4% of the women. For technical reasons, hydrosonography could not easily be done. At hysteroscopy signs of endometrium were found in 85% of the women, and synechiae were present in all women. The uterine cavity was partly occluded and narrowed. One woman had a total occlusion of the uterine cavity. Histopathological examination of the biopsies or curettage specimens from the uterine cavity showed endometrial tissue in 67% of the women.ConclusionsResidual endometrium was found in most women after TCRE and, therefore, if hormone replacement therapy is to be used, a combination of oestrogen with gestogen should be recommended. Intracavitary synechiae were present in most women after TCRE. The synechiae may have contributed to the cyclic pain experienced by 20 women after treatment. However, the synechiae did not seem to conceal the withdrawal bleeding or menstruation. If women who have undergone TCRE develop symptoms such as bleeding and/or pain, both vaginal ultrasound and hysteroscopy with directed biopsies should be recommended.
A second‐generation laparoscopic port system: EndoTIPTM
Authors: Ternamian Artin M. 
Published: March 2003

BackgroundEver since conventional laparoscopic trocars and cannulas were introduced, concern has been expressed regarding their safety, especially when they are used at the primary port. Despite considerable technological innovation, little has changed in port creation methods and instruments. Numerous publications from reputable centres around the world have warned of the potential dangers associated with their application and design. An interactive new port method is described and an access device is presented with several intuitive safety features which address most of these concerns.MethodThe new port system design evolved through a process of observation, the setting of minimum safety requirements and then cycles of system design, instrument design, prototype construction, evaluation, and redesign.ResultsThe main advantage of the new port system is the ability to introduce and remove laparoscopic ports in an incremental visual way, without the use of axial penetration force and without the use of a trocar. Our novel ergonomically designed access device allows the surgeon to navigate past vessels, bowel or adhesions during insertion and removal of the cannula, without compromising patient safety or port competence.ConclusionAn interactive visual port system which incorporates intuitive safety features will offer the surgeon an opportunity to better appreciate port dynamics, preserve port competence, and probably decrease laparoscopic access complications.
Morcellation in the bag: the superior solution to avoid spillage
Authors: Sinha Rakesh Y. , Joshi Kavita M. , Warty Neeta R. , Frey Brinda 
Published: March 2003

ObjectiveTo evaluate the new method of morcellation in the bag to avoid spillage of contents in the case of ovarian cysts.SettingA study of three procedures performed at an institute exclusively carrying out operative endoscopy.ConclusionWe found our technique of morcellation in the bag to be superior to other methods described.
Pyosalpinx presenting as an ectopic pregnancy
Authors: Bollen Bart , Lewis Victor 
Published: March 2003

ObjectiveTo report a case of a pyosalpinx presenting as an ectopic pregnancy.SubjectA 31‐year‐old patient was admitted with severe pain in the right iliac fossa 14 days after a curettage of the uterine cavity for missed abortion following 10 weeks of amenorrhoea.InterventionAn ultrasound scan showed a mass next to the right ovary with no evidence of retained products of conception. The β‐hCG level was 1258 IU l−1. A laparoscopy suggested an ectopic pregnancy in the distal end of the right tube. A salpingectomy was performed and the histopathological findings were of acute salpingitis.ConclusionWe describe a pyosalpinx after curettage of the uterine cavity, with high β.‐hCG levels from an intrauterine pregnancy, which indicated the wrong diagnosis of an ectopic pregnancy.
Growth of an endometrial polyp in a postmenopausal patient using raloxifene
Authors: Maia Jr Hugo , Maltez Amelia , Oliveira Maita , Almeida Marta , Coutinho Elsimar M. 
Published: March 2003

ObjectiveTo describe the association of raloxifene use with the development of an endometrial polyp in a postmenopausal patient.DesignCase report study.ResultsHysterosonography and hysteroscopy showed the occurrence of an endometrial polyp in a postmenopausal patient who had been using raloxifene for 8 months. Pathological investigation showed the presence of simple hyperplasia in the polyp. Oestrogen receptors were present in both the polyp and the atrophic endometrium. Progesterone receptors, on the other hand, were detected mainly in the atrophic endometrium. There was a focal p53 overexpression in the glandular epithelium of the polyp.ConclusionRaloxifene stimulated the development of an endometrial polyp in this postmenopausal patient. The presence of progesterone receptors in the atrophic endometrium suggests an agonistic action of raloxifene on this tissue.
The port‐decompression effect. A causative factor in the aetiology of post‐laparoscopic port‐site herniation?
Authors: Clark James T. M. , Byrne Dominic L. 
Published: March 2003

Introduction Post‐laparoscopic port‐site herniation has been variously reported to have an incidence of up to 0.2%. In 86% of instances where port sizes of 10 mm or greater have been used, and lateral port sites are 35 times more at risk than suprapubic, with the umbilical locale being the most common site, associated with 75% of all hernias. Theory A port decompressing an abdomen insufflated to a pressure of 15 mmHg has a profound suction effect and can pick up a loop of bowel while being drawn out through the abdominal wall. We believe that, on occasion, this is the mechanism by which bowel can be drawn within the abdominal wall and rectus sheath defect, thereby contributing to port‐site herniation. Methods We have obtained photographic evidence of bowel drawn up into a channel formed by a primary trocar. We demonstrate how bowel is caught by the suction effect of decompression through an open port and show that, despite the intraumbilical entry technique favoured by Garry, a channel can form through the abdominal wall which can trap bowel. We also examine the physics of gas flow and the relationship between port size, decompression technique and suction effect. Conclusion We suggest the abdomen should be decompressed slowly under direct vision, through the side tap, with the telescope remaining within the port. After gas release is completed, the primary port and telescope are removed together, with a clear view at all times that the port is free of any entrapped bowel.