bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential diagnosis of neonatal mild hypergalactosaemia detected by mass screening: Clinical significance of portal vein imaging
Authors: Nishimura Y. , Tajima G. , Bahagia A. Dwi , Sakamoto A. , Ono H. , Sakura N. , Naito K. , Hamakawa M. , Yoshii C. , Kubota M. , Kobayashi K. , Saheki T.
Published: February 2004

Summary: The aetiology of hypergalactosaemia in 100 neonates detected by screening using the Paigen method is discussed. Hypergalactosaemia was transient in 94 cases and persistent in 6. The aetiology among transient cases was unknown in 55, delayed closure of the ductus venosus in 19, heterozygous UDP‐galactose 4‐epimerase (GALE) deficiency in 16, and heterozygous galactose‐1‐phosphate uridyltransferase (GALT) deficiency in 6. The aetiology among persistent cases was hepatic haemangioendothelioma with portovenous shunting in 2, and patent ductus venosus with hypoplasia of the intrahepatic portal vein, citrin deficiency, homozygous GALE deficiency, and heterozygous GALE deficiency in one patient each. The abnormalities of the portal system were identified ultrasonographically at the initial consultation and measurements of the total bile acid and α‐fetoprotein concentrations were helpful in resolving the differential diagnosis. The causes of hypergalactosaemia varied, but a major cause was portosystemic shunt. Evaluation of patients with hypergalactosaemia should not be limited to enzymatic analysis, but should also include hepatic imaging, especially ultrasonography. Additionally, determination of total bile acids and α‐fetoprotein is helpful in identifying the aetiology of hypergalactosaemia in infants.
Diagnostic difficulties with common SURF1 mutations in patients with cytochrome oxidase‐deficient Leigh syndrome
Authors: Head R. A. , Brown R. M. , Brown G. K.
Published: February 2004

Summary: In three unrelated patients with systemic cytochrome oxidase deficiency resulting from mutations in the SURF1 gene, the same mutation in the splice donor site of intron 3 was identified. All three patients were compound heterozygotes, two for the common insertion/deletion mutation in exon 4. In all three cases, complete definition of the causative mutations was only resolved by combined analysis of cDNA and genomic DNA. Several factors were identified that contributed to the diagnostic difficulties: preferential amplification of deleted cDNA, significant formation of heteroduplexes in cDNA PCR amplification and unequal representation of heterozygous peaks in genomic DNA sequences. These patients emphasize the need to perform mutation analysis on both cDNA and genomic DNA wherever possible.
A family showing recessively inherited multisystem pathology with aberrant splicing of the erythrocyte Band 7.2b ('stomatin') gene
Authors: Argent A. C. , Chetty M. C. , Fricke B. , Bertrand Y. , Philippe N. , Khogali S. , von Düring M. , Delaunay J. , Stewart G. W.
Published: February 2004

Summary: The case of a French child, born of consanguineous parents of Tunisian origin, is described. He showed a severe multisystem disease with dyserythropoietic, sideroblastic anaemia, delayed neurological development with hypotonia and convulsions, salt‐losing nephropathy, chronic watery diarrhoea, lactic acidosis with mitochondrial dysfunction, brittle hair, hypergammaglobulinaemia, fatty liver with intermittent transaminasaemia, and terminal pulmonary fibrosis. Two siblings, of both sexes, were stillborn; two more lived only a short time. One sister is alive and well. SDS gel analysis of the red cell membranes showed a deficiency within ‘Band 7’ at 32 kDa. Analysis of the gene encoding ‘stomatin’, or ‘erythrocyte membrane protein 7.2b’, the principal protein of ‘Band 7’, revealed a complex series of aberrant spliceforms centred around exon 3, for which no explanatory genomic lesion could be found. The true underlying molecular cause of this condition remains obscure, but it suggests that the stomatin gene should be studied in other cases.
Bone mineral density and markers of bone turnover in patients with glycogen storage disease types I, III and IX
Authors: Cabrera‐Abreu J. , Crabtree N. J. , Elias E. , Fraser W. , Cramb R. , Alger S.
Published: February 2004

Summary: Patients with glycogen storage disease (GSD) types I, III and IX show reduced bone mineral content, but there is scarce data on new serum and urine markers of bone turnover or their relationship to bone densitometry. Six GSD I, four GSD III and four GSD IX patients underwent bone mineral density (BMD) measurement by dual‐energy X‐ray absorptiometry. Free pyridinoline (fPYD): creatinine and free deoxypyridinoline (fDPD):creatinine ratios were analysed on random urines. Procollagen type I C‐terminal propeptide, procollagen type I N‐terminal propeptide (PINP), carboxyterminal telopeptide of type I collagen and bone‐specific alkaline phosphatase were analysed in serum. Some GSD I and GSD III patients had low or very low BMD. There was no difference in total body BMD z‐score between the GSD types after adjusting for height (p=0110). Bone marker analysis showed no consistent pattern. Urine fPYD:creatinine ratio was raised in four GSD I and two GSD III patients, while serum PINP was inappropriately low in some of these patients. There was no clear correlation between any markers of bone destruction and total body z‐score, but the patient with the lowest total body z‐score showed the highest concentrations of both urinary fPYD:creatinine and fDPD:creatinine ratios. We conclude that some GSD I and GSD III patients have very low bone mineral density. There is no correlation between mineral density and bone markers in GSD patients. The inappropriately low concentration of PINP in association with the raised urinary fPYD:creatinine and fDPD:creatinine ratios seen in two GSD I patients reflect uncoupling of bone turnover. All these findings taken together suggest that some GSD I and GSD III patients may be at an increased risk of osteoporosis.
Blood acylcarnitine levels in normal newborns and heterozygotes for medium‐chain acyl‐CoA dehydrogenase deficiency: A relationship between genotype and biochemical phenotype?
Authors: Lehotay D. C. , LePage J. , Thompson J. R. , Rockman‐Greenberg C.
Published: February 2004

Summary: Patients with medium‐chain acyl‐CoA dehydrogenase (MCAD) deficiency are unable to metabolize medium‐chain fatty acids. Affected patients display a characteristic acylcarnitine profile when blood spots are collected after birth and analysed by tandem mass spectrometry. To determine the potential risk of metabolic decompensation in newborns with elevations of diagnostic metabolites (octanoylcarnitine>0.3, but <1 µmol/L), we investigated the relationship between octanoylcarnitine (C8) concentration in neonatal blood spots and the 985A>G MCAD genotype. Octanoylcarnitine values from 7140 newborns' blood spots were sorted. The highest C8 was 0.7 µmol/L, which is below the range in classical MCAD deficiency. Samples with C8 levels above 0.25 µmol/L (group C) represented 1.4% of the total. Values between 0.05 and 0.25 µmol/L (group B) made up 87.8% of the total; 10.8% of the samples had C8 values less than 0.05 µmol/L (group A). One hundred samples from each group were selected at random and genomic DNA was amplified by PCR and analysed for the presence of the 985A>G mutation. The analysed samples from groups A and B were all homozygous normal. The 100 samples from group C contained 26 samples that were heterozygous for the 985A>G mutation. These findings indicated that the frequency distribution of heterozygotes is not random within this population. Group C was further divided into C1, the 26 heterozygotes, and C2, the remaining 74 newborns in group C. In group C1 only 2 (8%) were in the ‘high‐risk’ group characterized by either low birth weight or requiring admission to the neonatal intensive care unit. In contrast, 28 (38%) from C2 had low birth weight or were in the neonatal intensive care unit. In our dataset, C8/C2 and C8/C12 ratios were also significantly elevated in both groups C1 and C2 compared to controls (group B). In contrast to what others have reported, the ratio of C8/C10 did not differentiate the group B controls from heterozygotes or other patients in metabolic distress (group C2), but were lower than those seen in classic MCAD or mild MCAD deficiency.
The distribution of white blood cell fat oxidation in health and disease
Authors: Pendergast D. R. , Fisher N. M. , Meksawan K. , Doubrava M. , Vladutiu G. D.
Published: February 2004

Summary: Fat oxidation is important for maintaining health and for supplying energy for exercise. We have proposed that the predisposition for individual rates of fat oxidation is determined genetically but may be modulated by acute exercise or exercise training. The purpose of this study was to examine cellular fat oxidation in white blood cells (WBC) using [9,10‐3H]palmitic acid. Sedentary controls free of symptoms (SED‐C, n=32), were compared with known carnitine palmitoyltransferase (CPT) II‐deficient patients (n=2), patients with fatiguing diseases (chronic fatigue syndrome, CFS, n=6; multiple sclerosis, MS, n=31), obesity (OB, n=5), eating disorders (ED, n=16), sedentary individuals prior to and after exercise (SED‐Ex, n=12), exercise‐trained sedentary individuals (SED‐Tr, n=12), and elite runners (ER, n=5). Fat oxidation in WBC for all subjects was normally distributed (mean=0.270±0.090 nmol/h per 109 WBC) and ranged from 0.09 nmol/h per 109 WBC in CPT II‐deficient patients to 0.59 nmol/h per 109 WBC in ER. There were no significant sex or acute exercise effects on WBC fat oxidation. Patients with MS, OB or ED were not different from SED‐C; however, in CPT II‐deficient patients, fat oxidation was low, while that of CFS patients was high. Exercise training in SED‐C resulted in a 16% increase in fat oxidation but in ER it was still 97% higher than in SED‐C. We propose that while WBC fat oxidation is not significantly affected by sex or acute exercise, and only by 15–20% with training, genetic factors play a role in determining both high and low fat oxidation in certain groups of individuals. The genetic predisposition for individual rates of fat oxidation may be easily measured using WBC fat oxidation, as has been shown for CPT II‐deficient patients and for elite runners. Ranges of WBC fat oxidation that are abnormally low (<20 nmol/h per 109 WBC, normal 20–35) or high (>35 nmol/h per 109 WBC) are proposed based on genetic factors evaluated in this study.
Isolated sulphite oxidase deficiency: clinical and biochemical features in an Italian patient
Authors: Schiaffino M. C. , Fantasia A. R. , Minniti G. , Caruso U. , Carnevale F. , Cerone R.
Published: February 2004

Summary: A patient with isolated sulphite oxidase deficiency presented with seizures at 12 h of life and followed a severe course, dying at 10 months of age. There was mild facial dysmorphism and the brain showed multiple cystic lesions.
Energy expenditure in patients with propionic and methylmalonic acidaemias
Authors: van Hagen C. C. , Weber E. Carbasius , van den Hurk Th. A .M. , Oudshoorn J. H. , Dorland L. , Berger R. , de Koning T.
Published: February 2004

Summary: Resting energy expenditure (REE) was investigated in 8 children with propionic and methylmalonic acidaemias because a lowered REE has been reported in the literature. We observed a marginally elevated REE and think thatadequate caloric intake and the use of a synthetic amino acid mixture are responsible for this.
CDG IIx with unusual phenotype
Authors: Cheillan D. , Cognat S. , Dorche C. , Jaeken J. , Vianey‐Saban C. , Guffon N.
Published: February 2004

Summary: Congenital disorders of glycosylation (CDG) are a group of genetic diseases characterized by defective protein glycosylation. N‐glycosylation defects are divided into two groups (I and II). CDG group II (types IIa to IIe) refers to defects in the Golgi processing of protein‐bound glycans. We report a patient with CDG IIx and an unusual phenotype.
Tay–Sachs disease in Brazilian patients: Prevalence of the IVS7+1g>c mutation
Authors: Rozenberg R. , Martins A. M. , Micheletti C. , Mustacchi Z. , Pereira L. V.
Published: February 2004

Summary: Seven Brazilian Tay–Sachs disease cases were screened for the most frequent causative mutations. They all presented at least one copy of the IVS7+1g>c mutation. Three patients were homozygotes, three were compound heterozygotes, and in one case only the mother was tested and shown to carry the IVS7+1g>c mutation. In the second allele the compound heterozygotes presented: R178H (the DN allele), InsTATC1278 and an unidentified mutation. The IVS7 + 1g>c mutation has already been described in three Portuguese patients. In this study, all families were unaware of any Portuguese ancestry. Since Brazil was a Portuguese colony, the mutation most probably came from ancient common ancestry. The initial molecular analysis of Tay–Sachs disease patients in Brazil indicated a prevalence of the IVS7+1g>c mutation, possibly as a result of genetic drift.
Straight‐chain acyl‐CoA oxidase deficiency presenting with dysmorphia, neurodevelopmental autistic‐type regression and a selective pattern of leukodystrophy
Authors: Kurian M. A. , Ryan S. , Besley G. T. N. , Wanders R. J. A. , King M. D.
Published: February 2004

Summary: We report a rare case of straight‐chain acyl‐CoA oxidase deficiency (McKusick 264470) presenting with dysmorphism, neurodevelopmental regression and leukodystrophy.
A subcritical instability of wave‐driven alongshore currents
Authors: Dodd Nick , Iranzo Vicente , Caballería Miquel
Published: February 2004

The development of shear instabilities of a wave‐driven alongshore current is investigated. In particular, we use weakly nonlinear theory to investigate the possibility that such instabilities, which have been observed at various sites on the U.S. coast and in the laboratory, can grow in linearly stable flows as a subcritical bifurcation by resonant triad interaction, as first suggested by Shrira et al. [1997]. We examine a realistic longshore current profile and include the effects of eddy viscosity and bottom friction. We show that according to the weakly nonlinear theory, resonance is possible and that these linearly stable flows may exhibit explosive instabilities. We show that this phenomenon may occur also when there is only approximate resonance, which is more likely in nature. Furthermore, the size of the perturbation that is required to trigger the instability is shown in some circumstances to be consistent with the size of naturally occurring perturbations. Finally, we consider the differences between the present case examined and the more idealized case of Shrira et al. [1997]. It is shown that there is a possibility of coupling between triads, due to the richer modal structure in more realistic flows, which may act to stabilize the flow and act against the development of subcritical bifurcations. Extensive numerical tests are called for.
Operational Space Environment Network Display (OpSEND)
Authors: Bishop Gregory , Bullett Terence , Groves Keith , Quigley Stephen , Doherty Patricia , Sexton Ethan , Scro Kevin , Wilkes Robert , Citrone Peter
Published: February 2004

The Air Force Research Laboratory and Space and Missile Systems Center, Detachment 11, have implemented a new system of graphical products that provide easy‐to‐visualize displays of space weather effects on various radio systems operating through the ionosphere. By means of a three‐level Web page, the user can select the radio system (UHF, HF, GPS, or radar), the map area (global or regional theater where the radio system is located), the time (nowcast or forecast), and additional options. This system, the Operational Space Environment Network Display (OpSEND), was first installed at the 55th Space Weather Squadron, Schriever Air Force Base (AFB), Colorado, and is now producing its first four products with a new Web format at the Air Force Weather Agency, Offutt AFB, Nebraska. Radar auroral clutter maps specify (nowcast) the estimated position and strength of the auroral oval relative to radar coverage regions. UHF Satcom scintillation maps nowcast and 2‐hour forecast ionospheric scintillation and its potential degradation to UHF Satcom communication links. HF illumination maps nowcast and 1‐hour forecast HF communication performance. Estimated GPS single‐frequency error maps nowcast and 1‐hour forecast positioning errors resulting from GPS constellation geometry and inaccurate ionospheric correction. Details and examples are presented.
GPS receiver performance characterization under realistic ionospheric phase scintillation environments
Authors: Morrissey Thomas N. , Shallberg Karl W. , Van Dierendonck A. J. , Nicholson Matthew J.
Published: February 2004

It is well known that ionospheric scintillation has the potential to affect all types of GPS receivers, even dual‐frequency military precise‐positioning service versions. In a previous effort the degree of degradation to Wide Area Augmentation System (WAAS) operation caused by scintillation, on the basis of simulated data input to an actual WAAS reference receiver under carefully controlled laboratory conditions at Space and Naval Warfare Systems Center, was analyzed and reported [Morrissey et al., 2000]. This degradation is manifested in increased errors for carrier phase and code range measurements and in a higher probability of loss of GPS signal track. However, the results supported the assessment that scintillation should not be a problem for WAAS receivers in the conterminous United States, except perhaps during the very rare occurrence of a “severe geomagnetic storm.” The previous work was briefed in a number of fora, and a detailed report was widely distributed throughout the ionospheric community along with a request for identification of any “gaps” in the results that could be addressed with further testing. From the feedback received, the following tests were conducted: (1) tests with long‐duration deep amplitude nulls, corresponding to the GPS signal moving with the ionospheric disturbance; (2) tests with phase scintillation waveforms derived from 50 Hz ionospheric scintillation monitor (ISM) data previously collected by the U.S. Air Force (Philips Laboratory) at Antofagosta, Chile; (3) tests of a modified military single‐frequency receiver (Enhanced Miniaturized Airborne GPS Receiver (EMAGR)) side‐by‐side with the WAAS receiver, with emphasis on maintaining lock at L1; and (4) tests at values of input carrier‐to‐noise ratio (CNR) lower (i.e., down to 36 dB Hz) than those used in the original tests. The tests with deep amplitude nulls were reported by Morrissey et al. [2002], and the tests with realistic input phase scintillation waveforms were reported at the Ionospheric Effects Symposium (IES) 2002. The current paper is based upon the IES 2002 results as modified by recent testing. Both these amplitude and phase results include EMAGR and low CNR performance.
Development of the Global Assimilative Ionospheric Model
Authors: Wang Chunming , Hajj George , Pi Xiaoqing , Rosen I. Gary , Wilson Brian
Published: February 2004

This paper provides an overview of the development of the Global Assimilative Ionospheric Model (GAIM) by a team of investigators from the University of Southern California (USC) and the Jet Propulsion Laboratory (JPL). The USC/JPL GAIM utilizes data assimilation techniques, which are widely used in meteorological applications, for the purpose of monitoring and forecasting Earth's ionosphere. We discuss the general structure of GAIM, which includes a first‐principles model of the ionosphere, a series of auxiliary models for the driving forces, a data processing subsystem, and an optimization subsystem. Two techniques for the estimation of electron density and driving forces in the ionosphere are presented: The four‐dimensional variational method and the Kalman filter. Some validation methods and results are also presented. These results demonstrate the potential of GAIM in providing accurate specification of the ionosphere.
Impact of changing land use practices on nitrate export by the Mississippi River
Authors: Donner Simon D. , Kucharik Christopher J. , Foley Jonathan A.
Published: February 2004

The increased use of nitrogen fertilizer in the Mississippi River Basin since the 1950s has been blamed for declining water quality, the degradation of aquatic ecosystems and the growth of a seasonal hypoxic zone in the Gulf of Mexico. In this study, we use the IBIS terrestrial ecosystem model and the HYDRA aquatic transport model to examine how agricultural practices and climate influenced terrestrial and aquatic nitrogen cycling across the Mississippi Basin and the nitrate export to the Gulf. The modeling system accurately depicts the observed trends and interannual variability in nitrate export by the Mississippi River (r2 > 0.83), and several of the major tributaries, between 1960 and 1994. The challenge of simulating nitrate export from the central western sub‐basins highlights the key role of processes like denitrification. The simulations demonstrate that three factors led to the doubling of nitrate export by the Mississippi River since 1960: (1) an increase in fertilizer application rates, particularly on maize; (2) an increase in runoff across the basin; and (3) the expansion of soybean cultivation. By the early 1990s, fertilized crops may have accounted for almost 90% of the nitrate leached to the river system, despite representing only 20% of the watershed area. The majority of the nitrate exported to the Gulf appears to originate from “hot spots,” including a stretch of the “Corn Belt” across Iowa, Illinois, and Indiana. The relative contribution of such heavily fertilized lands, particularly those in close proximity to higher order streams, can be even greater during wet years.
Volcanic vent self‐similar clustering and crustal thickness in the northern Main Ethiopian Rift
Authors: Mazzarini Francesco
Published: February 2004

The spatial distribution of volcanic vents in the northern Ethiopian Rift has been analysed in terms of their self‐similar clustering. The fractal distribution of vents has been computed for the monogenetic vents (cones, domes and maar) occurring along the rift valley and in the rift margin. The self‐similar clustering of vents has been computed through the analysis of vent centres coordinates by means of the two point correlation method. The vents of the northern Main Ethiopian Rift display a self‐similar clustering characterised by a correlation coefficient of 1.41 ± 0.02, with a size range defined by a lower cut‐off of 1.1 km and an upper cut‐off of 26.5 km. This analysis indicates a probable crustal thickness of 27 km, as indicated by the value of the computed upper cut‐off. This value compares well with other estimates for the crustal and lithosphere thickness in the Ethiopian Rift.
Quantification of relativistic electron microburst losses during the GEM storms
Authors: O'Brien T. P. , Looper M. D. , Blake J. B.
Published: February 2004

Bursty precipitation of relativistic electrons has been implicated as a major loss process during magnetic storms. One type of precipitation, microbursts, appears to contain enough electrons to empty the prestorm outer radiation belt in approximately a day. During storms that result in high fluxes of trapped relativistic electrons, microbursts continue for several days into the recovery phase, when trapped fluxes are dramatically increasing. The present study shows that this apparent inconsistency is resolved by observations that the number of electrons lost through microbursts is 10–100 times larger during the main phase than during the recovery phase of several magnetic storms chosen by the Geospace Environment Modeling (GEM) program.
The Madden‐Julian Oscillation (MJO) and northern high latitude wintertime surface air temperatures
Authors: Vecchi Gabriel A. , Bond Nicholas A.
Published: February 2004

The Madden‐Julian Oscillation (MJO) is the primary mode of large‐scale intraseasonal variability in the tropics. Recent work has connected the MJO to atmospheric variability in mid‐latitudes. We focus on relationships between the MJO and wintertime surface air temperatures in the Northern Hemisphere high latitudes. The MJO is diagnosed using principal EOF of 850 hPa zonal winds from the NCEP/NCAR Reanalysis for 1979–2002. Station data are used for surface air temperature in Alaska, Canada, the former U.S.S.R., Greenland, and Iceland. The phase of the MJO has a substantial systematic and spatially coherent effect on intraseasonal variability in wintertime surface air temperature through the global Arctic. Composites of geopotential height and specific humidity suggest that radiative and advective effects are important in the observed connections. These statistical connections may be useful for wintertime temperature forecasts. The mechanisms connecting intraseasonal tropical variability with polar and sub‐polar variability bear examination.
Analytical calculation of storm volume statistics involving Pareto‐like intensity‐duration marginals
Authors: Salvadori G. , De Michele C.
Published: February 2004

An analytical derivation of the storm volume distribution is given. The single storm is modeled as a rectangular pulse having non‐independent random duration and intensity. The structure of the dependence between storm duration and intensity is given via a suitable 2‐Copula, and the marginal distributions are endowed with Generalized Pareto laws, as recently pointed out in the hydrological Literature. The statistical properties of the rainfall volume are investigated, both analytically and using simulated samples; an application to rainfall data is also shown.
Is the wind stress forcing essential for the meridional overturning circulation?
Authors: Timmermann A. , Goosse H.
Published: February 2004

We use a global coupled atmosphere‐ocean sea‐ice model of intermediate complexity to demonstrate that wind‐forcing is a crucial element to sustain meridional overturning flow in the Atlantic. Neglecting wind‐stress in our multi‐century‐long simulations leads to a complete shutdown of the conveyor belt circulation. This result may have tremendous impacts for an assessment of the sensitivity of 2‐d climate models which typically do not capture wind‐driven gyres. It is argued that wind effects may be a key element in determining the fate and length of a collapsed THC state. Possible paleo implications will be discussed.
Oblique propagation of 30 s period fast magnetosonic foreshock waves: A Cluster case study
Authors: Eastwood J. P. , Balogh A. , Mazelle C. , Dandouras I. , Rème H.
Published: February 2004

It is accepted that the 30 s period Ultra‐Low‐Frequency waves observed in the terrestrial foreshock are generated by backstreaming ions through the ion‐ion right hand instability. However, such waves are generally observed to propagate obliquely to the field, in direct contrast to theoretical predictions of parallel propagation. A case study, based on data from Cluster, examining the oblique propagation of ULF waves when the IMF cone angle is large is presented. Errors associated with the analysis are considered. It is found that although the waves propagate obliquely to the magnetic field, they are principally confined to the plane defined by the magnetic field and the x GSE direction. The observed systematic deviation by ∼20° of the wave k vector in this plane is explained in terms of non‐local wave refraction processes, requiring careful consideration of the relative motion between the backstreaming ions and the upstream waves.
Prediction of tropical cyclone genesis using a vortex merger index
Authors: Venkatesh T. N. , Mathew Joseph
Published: February 2004

We propose a new method for detecting tropical cyclone genesis at an early stage by supposing merger of mesoscale midlevel vortices to be a common precursor event. The merger event serves as a selection mechanism and is a possible explanation of why only a small fraction of cloud clusters which meet the necessary conditions actually develop into tropical cyclones. The detection procedure uses satellite IR images which are available in near real‐time. After tests using data for the Bay of Bengal basin for the years 1999–2001, a real‐time test was conducted for the post‐monsoon 2002 and pre‐monsoon 2003 seasons. We found that the method was successful in detecting the formation of tropical cyclones 04B (2002) and 01B (2003) about 48 hours before they reached storm strength, and no storm escaped detection.
Dispersal scaling from the world's rivers
Authors: Warrick Jonathan A. , Fong Derek A.
Published: February 2004

Although rivers provide important biogeochemical inputs to oceans, there are currently no descriptive or predictive relationships of the spatial scales of these river influences. Our combined satellite, laboratory, field and modeling results show that the coastal dispersal areas of small, mountainous rivers exhibit remarkable self‐similar scaling relationships over many orders of magnitude. River plume areas scale with source drainage area to a power significantly less than one (average = 0.65), and this power relationship decreases significantly with distance offshore of the river mouth. Observations of plumes from large rivers reveal that this scaling continues over six orders of magnitude of river drainage basin areas. This suggests that the cumulative area of coastal influence for many of the smallest rivers of the world is greater than that of single rivers of equal watershed size.
Lower‐hybrid‐drift and modified‐two‐stream instabilities in current sheet equilibrium
Authors: Yoon Peter H. , Lui Anthony T. Y.
Published: February 2004

The present article discusses the stability of the thin current sheet against lower‐hybrid‐drift (LHDI) and modified‐two‐stream (MTSI) instabilities. It is demonstrated that MTSI is driven by the cross‐field current, implying that MTSI should also be most effective at the neutral sheet, while LHDI is driven by the density gradient, which is maximized near the edge of the current sheet. It is shown that under a normal Harris current sheet condition, Vi/∣Ve∣ = Ti/Te, LHDI completely dominates MTSI, which implies that linearly unstable current‐driven modes cannot penetrate to the center of the Harris current sheet. However, if the Harris current sheet condition is relaxed to Vi/∣Ve∣ > Ti/Te, then MTSI is shown to gradually overtake LHDI. This finding indicates that cross‐field drift linear instability dominated by MTSI feature may be operative at the center of the ion‐dominated thin current sheet.
Mechanisms for anomalous warming in the western Indian Ocean during dipole mode events
Authors: Prasad T. G. , McClean Julie L.
Published: February 2004

During a typical Indian Ocean Dipole mode (IOD) event the weakening and reversal of winds in the central equatorial Indian Ocean lead to the development of unusually warm sea surface temperatures (SSTs) in the western Indian Ocean. Here we report an analysis of model results and observations for the 1990–1999 period, showing the anomalous warming that occurred during 1997–1998 and 1994–1995 IOD events in the western Indian Ocean. It was primarily the result of the internal oceanic processes within the Arabian Sea rather than a direct response to external forcing from the eastern Indian Ocean as previously suggested. We compare the evolution of subsurface temperatures in the Arabian Sea just prior to (1996–1997: Representative of a normal year) and during the IOD event (1997–1998) to infer the physical processes responsible for the anomalous warming during the IOD events. In a normal year such as 1996 the existence of a unique open ocean upwelling feature, the Arabian Sea Dome (ASD), raises the thermocline in the southern Arabian Sea, a result of the positive wind stress curl of the winter monsoon. During an IOD year (1997), with the collapse of the monsoon wind system in the Arabian Sea the cold tongue, the strip of cool water indicative of ASD that normally occupies the southern Arabian Sea, fails to develop. As a result, the thermocline remains deep, which in turn enhances the heat content of the upper ocean, leading to warm SSTs. Volume‐integrated heat budget terms in the ASD region illustrate the role of horizontal and vertical advection in the upper ocean warming. An implication is that SSTs remain higher than 28°C in the southern Arabian Sea, thereby supporting large‐scale deep convection in the atmosphere during the winter monsoon. A band of deep convective cloud forms directly over the warm ASD region during the IOD events, which bring greater than average rainfall over the southern Arabian Sea and east Africa, whereas convection is suppressed over the cold ASD region during the normal years resulting in less than average rainfall.
A 15‐year West Antarctic climatology from six automatic weather station temperature and pressure records
Authors: Reusch David B. , Alley Richard B.
Published: February 2004

Apart from a small number of mostly coastal stations with human observers, automatic weather stations (AWS) are the dominant source of direct measurements of near‐surface climate parameters on the West Antarctic ice sheet. To help alleviate the shortage of surface meteorological data in Antarctica and to better exploit this invaluable data resource, we have used artificial neural network (ANN)‐based techniques to extend and fill data gaps in selected AWS records. Climatological analyses of the complete 15‐year temperature and pressure records (1979–1993) are reported here for six West Antarctic AWS sites (Siple Station, Byrd, Lettau, Marilyn, Elaine, and Ferrell) spanning ∼90° of longitude. Three sites (Siple, Lettau, and Marilyn) show significant warming trends during the austral summer season (December–February). Warm anomalies of 2°–5°C appeared at all sites during 1980 (winter) and 1989 (winter‐spring) with a cold anomaly of up to 3°C during fall 1982. Average intersite seasonal correlation comparisons are highest during fall and winter and lowest in summer; Byrd correlates with no other sites in summer. All sites have short, sharp temperature transitions during the fall and spring seasons and a relatively stable winter season with occasional early to midwinter warmings. Typical winter season conditions are present for up to 5–6 months of the year. An exception occurs at Byrd during 1988 and 1989, when climatologically normal winter conditions did not appear to become fully established. Mean monthly temperatures during this unusual period were 5°–10°C above normal.
Crustal magnetic field of Mars
Authors: Langlais B. , Purucker M. E. , Mandea M.
Published: February 2004

The equivalent source dipole technique is used to model the three components of the Martian lithospheric magnetic field. We use magnetic field measurements made on board the Mars Global Surveyor spacecraft. Different input dipole meshes are presented and evaluated. Because there is no global, Earth‐like, inducing magnetic field, the magnetization directions are solved for together with the magnetization intensity. A first class of models is computed using either low‐altitude or high‐altitude measurements, giving some statistical information about the depth of the dipoles. Then, a second class of models is derived on the basis of measurements made between 80 and 430 km altitude. The 4840 dipoles are placed 20 km below the surface, with a mean spacing of 2.92° (173 km). Residual rms values between observations and predictions are as low as 15 nT for the total field, with associated correlation coefficient equal to 0.97. The resulting model is used to predict the magnetic field at 200‐km constant altitude. We present the maps of the magnetic field and of the magnetization. Downward continuation of a spherical harmonic model derived from our equivalent source solution suggests that intermediate‐scale lithospheric fields at the surface probably exceed 5000 nT. Given an assumed 40‐km‐thick magnetized layer, with a mean volume per dipole equal to 3.6.106 km3, the magnetization components range between ±12 A/m. We also present apparent correlations between some impact craters (≥300‐km diameter) and magnetization contrasts. Finally, we discuss the implications of the directional information and possible magnetic carriers.
Martian geomorphology from fractal analysis of drainage networks
Authors: Stepinski T. F. , Collier M. L. , McGovern P. J. , Clifford S. M.
Published: February 2004

An alternative approach to conventional planetary terrain analysis is proposed. Martian terrains, represented by topography based on the Mars Orbiter Laser Altimetry (MOLA) data, are represented as a series of drainage basins, regardless of the historical presence or absence of actual fluid flow. A fractal analysis of each drainage network, computationally extracted from an underlying terrain, yields a network descriptor, a list of four numbers that describes the traits of a network. Network descriptors are used for a quantitative characterization and classification of Martian surfaces. We have extracted and analyzed 387 drainage networks from 74 Martian locations, representing all major epochs and geological units, to investigate whether their network descriptors are capable of differentiation between different epochs and geological units. We have found that our approach can distinguish morphologically different terrains, but only in a statistical sense. In particular, the method could be used to measure the degree of surface cratering and thus the age of the surface. In addition, for surfaces that are not heavily cratered the method is capable of distinguishing between different geological units. We have found no global trends in the character of Martian drainage networks; their network descriptors show no systematic dependence on location or elevation. Our analysis reveals that all Noachian surfaces grouped in the Npld geological unit have very similar network descriptors, regardless of prominence and integration of their visible fluvial features. The comparison between statistical description of Npld and terrestrial drainage networks shows overall similarities, but also some marked differences. Because of these differences, the notion of sustained rainfall on Mars during the Noachian epoch is inconsistent with our findings, but a limited rainfall is compatible with our results.
Formation of double‐ring circular grabens due to volumetric compaction over buried impact craters: Implications for thickness and nature of cover material in Utopia Planitia, Mars
Authors: Buczkowski Debra L. , Cooke Michele L.
Published: February 2004

Throughout the polygonal terrain of Utopia Planitia are circular grabens, inferred to overlie buried crater rims. Thirty‐four of the 37 circular grabens discovered in Viking and Thermal Emission Imaging System (THEMIS) images southwest of the Utopia Basin (21°–36°N, 240°–265°W) have two nested rings, while the remaining three have a single ring. All 37 circular grabens bound topographic depressions whose surface relief scales directly with diameter, suggesting differential compaction of cover material within the polygonal terrain. The distance of doubled circular grabens from the center of the Utopia Basin scales directly with the spacing between the two rings, implying a relation between ring spacing and cover thickness. Numerical models of horizontal shrinkage during volumetric compaction of material over crater rims show two maxima of horizontal normal tension on the surface. These maxima, where we would expect grabens to form, move away from each other with increasing cover thickness. The modeled spacings of stress maxima within 1–2 km thick cover are comparable to the graben spacing observed in southwest Utopia Planitia, implying that cover thickness in this polygonal terrain may be 1–2 km thick. Where cover material is thin, the proximity of the two normal stress maxima may only produce a single circular graben, accounting for the observation that the three single‐ringed grabens are most distal to the center of the basin. We contend that the correlation of shrinkage model results and observed ring spacing supports a wet sedimentary origin of polygonal terrain materials, consistent with the past existence of standing water in the Martian lowland.
Modeling of the interactions between forest vegetation, disturbances, and sediment yields
Authors: Istanbulluoglu Erkan , Tarboton David G. , Pack Robert T. , Luce Charles H.
Published: February 2004

The controls of forest vegetation, wildfires, and harvest vegetation disturbances on the frequency and magnitude of sediment delivery from a small watershed (∼3.9 km2) in the Idaho batholith are investigated through numerical modeling. The model simulates soil development based on continuous bedrock weathering and the divergence of diffusive sediment transport on hillslopes. Soil removal is due to episodic gully erosion, shallow landsliding, and debris flow generation. In the model, forest vegetation provides root cohesion and surface resistance to channel initiation. Forest fires and harvests reduce the vegetation. Vegetation loss leaves the land susceptible to erosion and landsliding until the vegetation cover reestablishes in time. Simulation results compare well with field observations of event sediment yields and long‐term averages over ∼10,000 years. When vegetation is not disturbed by wildfires over thousands of years, sediment delivery is modeled to be less frequent but with larger event magnitudes. Increased values of root cohesion (representing denser forests) lead to higher event magnitudes. Wildfires appear to control the timing of sediment delivery. Compared to undisturbed forests, erosion is concentrated during the periods with low erosion thresholds, often called accelerated erosion periods, following wildfires. Our modeling suggests that drainage density is inversely proportional to root cohesion and that reduced forest cover due to wildfires increases the drainage density. We compare the sediment yields under anthropogenic (harvest) and natural (wildfire) disturbances. Disturbances due to forest harvesting appear to increase the frequency of sediment delivery; however, the sediment delivery following wildfires seems to be more severe. These modeling‐based findings have implications for engineering design and environmental management, where sediment inputs to streams and the fluctuations and episodicity of these inputs are of concern.
Laboratory study of the underground sound generated by debris flows
Authors: Huang Ching‐Jer , Shieh Chieng‐Lun , Yin Hsiao‐Yuan
Published: February 2004

This experimental study investigates the underground sound generated by different kinds of rock motions that occur in debris flows. The experiments were divided into two parts. The first part consisted of measuring the main characteristics of the underground sound caused by friction of a rock rubbed against a bed of gravel and of that caused by a free‐falling rock hitting a similar bed of gravel. In the second part a hydrophone was installed at the bottom of a laboratory channel to measure the underground sound of debris flows in that channel. The sound signals were analyzed using both the fast Fourier transform and the Gabor transform to represent the signals in both the frequency and time‐frequency domains. The measurement results reveal that the frequency of the sound generated by the rock‐gravel bed friction is relatively low, being mostly between 20 and 80 Hz. In contrast, the frequency range of the collision sound is relatively higher, between 10 and 500 Hz. Finally, the frequency of the underground sound caused by the debris flows in the flume is in the range of 20–300 Hz.
Reversible myopathy during successful treatment with pegylated interferon and ribavirin for acute hepatitis C
Authors: Golstein P. E. , Delforge M. L. , Deviere J. , Marcellin P.
Published: February 2004

There is no standard approved treatment for acute hepatitis C and the combination of pegylated interferon‐αand ribavirin, currently recognized as the standard of care for chronic hepatitis C, has not been evaluated for acute hepatitis C. Adverse events induced by interferon therapy are numerous but myopathy is rare and has not been described with the use of pegylated interferon‐α. We report the case of a 33‐year‐old Caucasian man who was successfully treated for acute hepatitis C with the combination of pegylated interferon‐α2b and ribavirin, and who during treatment developed myopathy which proved reversible.
Origins of mangrove ecosystems and the mangrove biodiversity anomaly
Authors: Ellison Aaron M. , Farnsworth Elizabeth J. , Merkt Rachel E.
Published: February 2004

1. Mangrove species richness declines dramatically from a maximum in the Indo‐West Pacific (IWP) to a minimum in the Caribbean and Western Atlantic. Explaining this ‘anomalous’ biogeographic pattern has been a focus of discussion for most of this century.2. Two hypotheses have been put forward to explain the mangrove biodiversity anomaly. The ‘centre‐of‐origin hypothesis’ asserts that all mangrove taxa originated in the IWP and subsequently dispersed to other parts of the world. The ‘vicariance hypothesis’ asserts that mangrove taxa evolved around the Tethys Sea during the Late Cretaceous, and regional species diversity resulted from in situ diversification after continental drift.3. Five lines of evidence are used to test between these two hypotheses. First, we review the mangrove fossil record. Second, we compare modern and fossil distributions of mangroves and eight genera of gastropods that show high fidelity to the mangrove environment. Third, we describe species‐area relationships of mangroves and associated gastropods with respect to area of available habitat. Fourth, we analyse patterns of nestedness of individual plant and gastropod communities in mangrove forests. Fifth, we analyse patterns of nestedness of individual plant and gastropod species.4. All five lines of evidence support the vicariance hypothesis. The first occurrences in the fossil record of most mangrove genera and many genera of gastropods associated with mangrove forests appear around the Tethys Sea from the Late Cretaceous through the Early Tertiary. Globally, species richness in any given mangrove forest is tightly correlated with available area. Patterns of nestedness at the community and species‐level both point towards three independent regions of diversification of mangrove ecosystems: South‐east Asia, the Caribbean and Eastern Pacific, and the Indian Ocean region.
Ancient latitudinal gradients of C3/C4 grasses interpreted from stable isotopes of New World Pleistocene horse (Equus) teeth
Authors: Macfadden Bruce J , Cerling Thure E , Harris John M , Prado José
Published: February 2004

Carbon and oxygen isotopic data are reported from 116 Pleistocene Equus teeth from sixty‐six localities in the New World ranging from 68°N (Alaska, Canada) to 35°S (Argentina). Equus species have been predominantly grazers, and as such, carbon isotopic values of their tooth enamel provide evidence of the Pleistocene distribution of C3 and C4 grasses. The carbon data presented here indicate a gradient (δ13C range of 10 parts/mil) in the relative proportion of C3 and C4 grasses between high latitude and equatorial Equus samples. The largest amount of change from C3 to C4 grasses during the Pleistocene occurred in the mid‐latitudes between about 30 to 40°. The oxygen data, which vary proportionately with temperature, indicate a latitudinal gradient (δ18O range of 20 parts/mil) between high‐latitude and equatorial Equus samples. The basic pattern of latitudinal gradients of C3/C4 grass distribution and temperature as interpreted from these Pleistocene data is similar to the modern‐day. The use of stable isotopes of fossil herbivore teeth represents a new means to interpret Pleistocene climates and terrestrial ecology.