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- Hillier, Ladeana W, et al.
(författare)
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Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
- 2004
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 432:7018, s. 695-716
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Tidskriftsartikel (refereegranskat)abstract
- We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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| 3. |
- Jain, SC, et al.
(författare)
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Transient enhanced diffusion of boron in Si
- 2002
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 91:11, s. 8919-8941
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Forskningsöversikt (refereegranskat)abstract
- On annealing a boron implanted Si sample at similar to800 degreesC, boron in the tail of the implanted profile diffuses very fast, faster than the normal thermal diffusion by a factor 100 or more. After annealing for a sufficiently long time, the enhanced diffusion saturates. The enhanced diffusion is temporary, on annealing the sample a second time after saturation, enhanced diffusion does not occur. It is therefore designated as transient enhanced diffusion (TED). The high concentration peak of the implanted boron profile, which is electrically inactive, does not diffuse. TED makes it difficult to fabricate modern Si based devices, in particular TED produces the parasitic barriers which degrade the performance of the SiGe heterostructure bipolar transistors and TED can limit the fabrication of shallow junctions required for sub-100 nm complementary metal-oxide-semiconductor technology. The mechanisms of TED have been elucidated recently. A Si interstitial "kicks out" the substitutional boron atom to an interstitial position where it can diffuse easily. Alternatively the interstitials and boron atoms form highly mobile pairs. In both cases Si interstitials are required for the diffusion of boron. Therefore the enhanced boron diffusivity is proportional to the concentration of the excess Si interstitials. The interstitials are injected during implantation with Si or dopant ions. The interstitials are also injected during oxidation of the Si surface. Therefore the diffusivity increases temporarily in both cases. Even at relatively low annealing temperatures (similar to800 degreesC) the mobility of the interstitials is high. The TED at this temperature lasts for more than 1 h. This large TED time can be explained by the presence of interstitial clusters and interstitial-boron clusters. The interstitial clusters are the {311} extended defects and dislocation loops. The precise structure of interstitial-boron clusters is not yet known though several models have been proposed. The clusters are the reservoirs of the interstitials. When the supersaturation of interstitials becomes low, the clusters dissolve and emit interstitials. The interstitials emitted from the clusters sustain the TED. Many groups have suggested that the rate of emission of interstitials is determined by Ostwald ripening of the clusters. However, recently TED evolution has also been explained without invoking Ostwald ripening of the {311} defects. The evidence of Ostwald ripening of dislocation loops is more direct. In this case the Ostwald ripening has been confirmed by the measurements of the size distributions of the dislocation loops at different times and temperatures of annealing. At higher temperatures the extended clusters are not stable and coupling between the interstitials and boron atoms is reduced. Therefore at high temperatures TED lasts only for a short time. At high temperatures the displacement during TED is also small. This suggests that if rapid thermal annealing with high ramp rates is used, TED should be suppressed. Currently high ramp rates, 300-400 degreesC/s are being tried to suppress TED.
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| 4. |
- Utarini, Adi, 1965-
(författare)
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Evaluation of the user-provider interface in malaria control programme : The case of Jepara District, Central Java Province, Indonesia
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Early detection and case management remain the main strategies in malaria control programme (MCP) in a low endemic area such as in Java Island, Indonesia. These strategies require an understanding of the community’s care-seeking behaviour in relation to the various health services. Since most malaria cases in Java are diagnosed at home by the village malaria workers (VMWs), this study aimed to examine the user-provider interface in early detection and case management of malaria, particularly the interaction between the clinical malaria patients and the VMWs. Methods: The number of blood slides examined and the laboratory results over a 20-year period were retrieved from the routine malaria surveillance system. The population at risk of malaria and the rainfall data were obtained from secondary sources. In addition, age, sex, malaria species, types of drugs, drug and dosage and time lapse between slides taken and examined were recorded from the malaria registers at the three endemic health centres from 1994-1998. The quality of diagnosis was examined by re-reading 153 slides at the Faculty of Medicine, Gadjah Mada University. Prior to using rapid assessment procedures (RAP), we proposed 11 criteria and applied these to 15 published RAP studies in health. For each of the papers, two authors assessed the adequacy of information provided independently. Using the criteria as a guideline for developing a protocol, a RAP study of malaria was thereafter carried out. Data were retrieved from 38 free-listings, 28 in-depth interviews, seven focus group discussions and unstructured observation. A qualitative thematic content analysis was applied. Finally, based on the RAP results, a one-year longitudinal study of care-seeking behaviour of all clinical malaria cases treated by the VMWs was conducted in Mlonggo II area. Age, sex, daily actions and date of consultations were recorded by all VMWs in a diary that covered prior all contacts between the patients and the VMWs. Also, 24 interactions between the VMWs and the patients were audiotaped. Results: The incidence of malaria during the 1990s fluctuated, albeit at the lower level than that of the 1980s, and it reached a peak (3.5/1000 population) during an outbreak in 1996-97. There was no clear association between the El Nino phenomenon and incidence of malaria. The incidence was almost twice as high in children <15 years than in adults (15+ years). In <5 year old children the risk of P. vivax malaria was higher than the risk of P. falciparum. Comparisons between active and passive case detection (ACD and PCD) showed that almost 60% of 10, 493 confirmed malaria cases in Jepara were identified from ACD. ACD also detected significantly higher percentage of P. falciparum gametocyte infections than PCD (14.7% vs. 5.7%). The duration between slides taken to examination was however longer for ACD than for PCD (2.3 vs. 1.1 days). Applying the criteria to the published RAP studies, it was found that information was limited to address subjectivity, staff and ethics criteria. In Jepara, malaria (known as katisen or panas tis) was considered a common but minor illness. This was also reflected by the most common action taken by the patients, i.e. not doing anything. However, when the illness was perceived as important, the community had a good access to different health care providers. Eighty seven percent of cases had been treated by the VMWs on day four of the illness period. On day two, the proportion not treated was significantly higher in male than in female cases (60.7% and 54.6%; p 0.01) and in those <15 years of age compared with those 15+ years (71.3% and 56.9%; p<0.001). Insufficient understanding of malaria signs and symptoms likely leads to delay in illness recognition and treatment. Interactions between the VMWs and the patients were mostly focused on medical tasks, and low compliance with treatment was a common concern of the VMWs in the interaction. Conclusion: El Nino phenomenon was not associated with an epidemic in Jepara. A possible association between age and the risk of P. vivax malaria needs further investigation. In this decentralised health care system, ACD should be continued in a focus endemic area and therefore, efforts to retain the VMWs should be considered. This research showed similar findings between the RAP study and the longitudinal study. A consistent gap was found between the common understanding and the biomedical description of malaria. The performance of the VMWs supports the MCP through early contact with clinical malaria patients. Visits of VMWs within four days of symptom recognition appear to be the ideal situation for both the programme and the community. If case management continues to be the main strategy in MCP in this low endemic area, the emic perspective of the people must be well integrated to improve home treatment. Likewise, simple interventions to strengthen the role of VMWs in home management should be conducted.
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