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  • Springer  (108)
  • Blackwell Science Pty  (16)
  • Macmillian Magazines Ltd.  (16)
  • Nature Publishing Group (NPG)
  • 2000-2004  (140)
  • 1
    ISSN: 1573-773X
    Keywords: principal component analysis ; sequential extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract When increasing numbers of principalcomponents are extracted by using the sequentialmethod proposed in [1] by Banour and Azimi-Sadjadi, the accumulated extractionerror will become dominant and affect the extractionsof the remaining principal components. To improvethis, we suggest that the initial weight vector forthe extraction of the next component should beorthogonal to the eigensubspace spanned by the alreadyextracted weight vectors. Simulation results showthat both the convergence and the accuracy of theextraction are improved. Our improved method is alsocapable of extracting full eigenspace accurately.
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  • 2
    ISSN: 1432-0509
    Keywords: Key words: MR imaging—MR cholangiopancreatography—Pancreaticobiliary system—Gadolinium-DTPA—Oral negative contrast agent.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: We investigated the feasibility of using intravenous magnetic resonance (MR) contrast agent as a gastrointestinal oral negative contrast agent to null the bowel signal during MR cholangiopancreatography (MRCP). Methods: In the first part of the study, a phantom study was performed to select the optimal concentration of MR contrast agent to be used as an oral negative contrast agent in MRCP. In the second part of the study, 23 consecutive patients suffering from different pancreaticobiliary diseases were imaged with a single-shot fast spin-echo pulse sequence. The data acquisition was started without oral contrast agent and then repeated with oral contrast agent. From the MR images taken with and without oral contrast agent, the gallbladder, cystic duct, common bile duct, and pancreatic duct were assessed and graded by two radiologists. Results: The oral contrast agent was tolerated well by all patients. In all patients the high signal intensity from the intestinal fluid was completely suppressed. The depictions of the gallbladder and cystic duct were slightly and moderately improved, respectively, whereas the depictions of the common bile duct and pancreatic duct were markedly improved by the oral contrast agent administration. Conclusion: Diluted intravenous MR contrast agent can be an effective and safe oral negative contrast agent in eliminating signal intensity of the gastrointestinal tract, thus improving the depiction of the biliary system in MRCP.
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  • 3
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The aim of the present project is to determine the feasibility of measuring hepatic cytochrome P4501A1 (CYP1A1) and metallothionein (MT) mRNA in fish as an integrative measurement of persistent organic pollutants (POPs) and heavy metal contamination in sediment arising in Hong Kong. Sediment samples were collected from different sites, including Victoria Harbour (VS6), Yim Tin Tsai (YTT) at Tolo Harbour, Mai Po marshes (MPM) at Deep Bay, and Southern Waters (SS6) of coastal waters. The samples were analyzed for total and extractable concentrations of Cd, Cu, Ni, Zn, and Pb, as well as PCBs and PAHs. In addition, biomarker responses were studied in tilapia exposed experimentally to coastal sediment for 7 days. Using RT-PCR technique, hepatic CYP1A1 and MT mRNA were measured. Three control groups were used, including one negative control group maintained in sea water only; the second and third positive control groups were in sea water but were intraperitoneally injected with either β-naphthoflavone (40 μg/g body weight) or cadmium chloride (10 μg/g body weight), respectively. The chemical data showed that VS6, YTT, and MPM were classified as Class C sediment according to the sediment quality criteria defined by the Hong Kong Environmental Protection Department, indicating the sites were heavily polluted. The exposure of tilapia to the sediment induced hepatic CYP1A1 (VS6 〉 YTT 〉 MPM 〉 SS6) and MT (VS6 〉 MPM 〉 YTT 〉 SS6) levels. The induction patterns were comparable to the levels of POPs and metal contamination in the sediment, indicating that the biomarker responses could be used to differentiate low to high levels of contamination among sediment.
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  • 4
    ISSN: 1573-7578
    Keywords: mutual exclusion ; quorum consensus ; distributed systems ; replicated database systems ; fault-tolerant computing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Many quorum consensus protocols have been proposed for the management of replicated data in a distributed environment. The advantages of a replicated database system over a non-replicated one include high availability and low response time. We note further that the multiple sites can act as multiple agents so that at any time, multiple requests can be handled in parallel. This feature leads to the desirable consequence of high workload capacity. In this paper, we define a new metric of read-capacity for this feature. We propose a new protocol called diamond quorum consensus which has two major properties that are superior to the previous protocols of majority, tree, grid, and hierarchical quorum consensus: (1) it has the highest read-capacity, (2) it has the smallest optimal read quorum size of 2. We show that these two features are achievable without jeopardizing the availability. The small quorum size is a significant feature because it relates to the messaging cost. Few previous work on quorum consensus has discussed the handling of partition failure, which in many cases will depend on the quorum consensus protocol, we show how we can use the generalized virtual partition protocol to handle partition failure in the case of diamond quorum consensus.
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  • 5
    ISSN: 1432-203X
    Keywords: Key words Agrobacterium-mediated transformation ; B.t. insecticidal protein gene ; B. campestris ssp.parachinensis ; Transgenic plants ; Insect resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  An effective plant regeneration procedure and a gene transfer system via Agrobacterium tumefaciens were developed in Brassica campestris ssp. parachinensis. Hypocotyls from 5-day-old seedlings with 2 days pre-culture were infected with Agrobacterium strain MOG301 harboring a binary vector containing a synthetic Bacillus thuringiensis (B.t.) cry1Ab or cry1Ac gene with full codon-modification. After culture and selection on MS medium supplemented with 4.0 mg/l BAP, 2.0 mg/l NAA, 70 μM AgNO3 and 50 mg/l kanamycin, a number of kanamycin-resistant plantlets were regenerated. PCR and Southern blotting analysis were used to identify and characterize the transgenic plants with the integrated cry1Ab or cry1Ac gene. Western blotting analysis of the transgenic plants confirmed the expression of insecticidal proteins encoded by cry1Ab or cry1Ac. Subsequent bioassay with larvae of the Diamondback moth, Plutella xylostella, demonstrated that the transgenic plants were resistant to feeding damage.
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  • 6
    ISSN: 1439-0973
    Keywords: Key Words Cytomegalovirus ; Malnutrition ; Pneumocystis carinii ; Zinc deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The case of a term infant with congenital cytomegalovirus (CMV) infection who developed Pneumocystis carinii pneumonia (PCP) at 4 months of age is reported. Our patient suffered from severe malnutrition and zinc deficiency secondary to necrotizing enterocolitis since the age of 2 months. There was no evidence of human immunodeficiency virus infection. Qualitative and quantitative in vitro leukocyte functions were also normal. This case highlights the fact that PCP can occur in apparently immunocompetent term infants. Malnourished infants with zinc deficiency or congenital CMV infection are at increased risk of developing PCP.
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  • 7
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
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  • 8
    ISSN: 1432-1041
    Keywords: Key words Rofecoxib ; Pharmacokinetics ; COX-2 specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Prostaglandin synthesis is catalyzed by a constitutive cyclo-oxygenase isoform (COX-1) and an inducible isoform (COX-2). It is hypothesized that the analgesic and anti-inflammatory effects of nonsteroidal anti-inflammatory drugs (nonspecific COX-1/COX-2 inhibitors) such as ibuprofen principally derive from COX-2 inhibition. The purpose of this study was to evaluate steady-state pharmacokinetics, biochemical selectivity and tolerability of rofecoxib (VioxxTM), characterized in vitro as a COX-2 inhibitor. Methods: Four panels of healthy men (n=8 per panel) were administered rofecoxib (n=6) (25, 100, 250, 375 mg) or placebo (n=2) once daily on day 1 and days 3–14. Blood samples for assays of rofecoxib plasma concentration and COX isoform activity were obtained pre-dose and at specified time points post-dose. Results: Rofecoxib pharmacokinetics were found to be complex and nonlinear. Elimination half-life ranged from 9.9 h to 17.5 h after multiple dosing with an accumulation ratio close to 2 for all doses. COX-2 inhibitory activity as assessed by average inhibition of whole blood lipopolysaccharide-stimulated prostaglandin E2 over the 8-h post-dose period on day 14 was 0.3, 67, 96, 92 and 96% for the placebo and the 25-, 100-, 250- and 375-mg treatment groups, respectively. No treatment group showed significant inhibition of COX-1 as assessed by thromboxane B2 generation in clotting whole blood. Side effects were mild and transient. Conclusion: The results indicate that rofecoxib is a potent and specific inhibitor of COX-2 in humans even at doses more than tenfold higher than those associated with efficacy in patients with osteoarthritis.
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  • 9
    ISSN: 1432-1076
    Keywords: Key words Vallecular cyst ; Neonate ; Infant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Vallecular cyst, a rare but generally benign lesion in the larynx, may cause stridor and even life-threatening airway obstruction in early infancy. We retrospectively studied 14 cases of newborn infants with vallecular cyst. There was no gender predilection and most cases were full-term and appropriate for gestational age. The clinical presentations included stridor, chest wall retraction, feeding difficulties and failure to thrive. Laryngomalacia was the most common associated anomaly. Flexible laryngoscopy was sufficient for diagnosing the vallecular cyst and larygmalacia. Maintenance of airway patency, nutritional support, and de-roofing of the cyst were the mainstays of management. Conclusion Vallecular cyst should be included in the differential diagnosis of stridor in newborn infants. Respiratory and feeding difficulties in these patients can be dramatically improved after appropriate surgical removal of the cyst.
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  • 10
    ISSN: 1432-1076
    Keywords: Key words Childhood necrotising pneumonitis ; Empyema ; Video-assisted thoracoscopic surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We retrospectively analysed the clinical features and outcome of children under 17 years of age with necrotising pneumonitis (NP). The radiographs and CT scans of the chest of children under 17 years of age between July 1995 and March 1999 who had complicating community-acquired pneumonia were reviewed. CT scans were obtained for persistent fever, respiratory distress and sepsis despite empiric antibiotic therapy and closed tube drainage. A total of 21 children had the radiographic features of NP of whom 11 (52%) patients were successfully managed using antibiotic therapy with or without closed tube drainage. Ten patients required thoracoscopic decortications and/or lysis of pleural adhesions or debridement of empyema due to refractory pleural sepsis, failure of pulmonary re-expansion and persistent air-leaks. The most common pathogens identified were Streptococcus pneumoniae (n=3),Staphylococcus aureus (n=2), and Haemophilus influenzae type b (n=2). The days of hospital stay, duration of fever and days of C-reactive protein return to normal were significantly less for the medically versus the surgically treated children (P 〈 0.05). Conclusion The clinical course of necrotising pneumonitis in children following complicated pneumonia is often prolonged despite adequate antibiotic therapy. Necrotising pneumonitis with co-existing multiple loculations, pneumothorax/bronchopleural fistula in the empyema and extensive pleural peel are poor prognostic factors for medical therapy. Thoracoscopic removal of loculated empyema, lysis of adhesions and/or decortication are effective in relieving tachypnoea, chest pain, and controlling fever and improve the outcome, especially in children with empyema.
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