2,024 research outputs found
A new SATIRE-S spectral solar irradiance reconstruction for solar cycles 21--23 and its implications for stratospheric ozone
We present a revised and extended total and spectral solar irradiance (SSI)
reconstruction, which includes a wavelength-dependent uncertainty estimate,
spanning the last three solar cycles using the SATIRE-S model. The SSI
reconstruction covers wavelengths between 115 and 160,000 nm and all dates
between August 1974 and October 2009. This represents the first full-wavelength
SATIRE-S reconstruction to cover the last three solar cycles without data gaps
and with an uncertainty estimate. SATIRE-S is compared with the NRLSSI model
and SORCE/SOLSTICE ultraviolet (UV) observations. SATIRE-S displays similar
cycle behaviour to NRLSSI for wavelengths below 242 nm and almost twice the
variability between 242 and 310 nm. During the decline of last solar cycle,
between 2003 and 2008, SSI from SORCE/SOLSTICE version 12 and 10 typically
displays more than three times the variability of SATIRE-S between 200 and 300
nm. All three datasets are used to model changes in stratospheric ozone within
a 2D atmospheric model for a decline from high solar activity to solar minimum.
The different flux changes result in different modelled ozone trends. Using
NRLSSI leads to a decline in mesospheric ozone, while SATIRE-S and
SORCE/SOLSTICE result in an increase. Recent publications have highlighted
increases in mesospheric ozone when considering version 10 SORCE/SOLSTICE
irradiances. The recalibrated SORCE/SOLSTICE version 12 irradiances result in a
much smaller mesospheric ozone response than when using version 10 and now
similar in magnitude to SATIRE-S. This shows that current knowledge of
variations in spectral irradiance is not sufficient to warrant robust
conclusions concerning the impact of solar variability on the atmosphere and
climate.Comment: 25 pages (18 pages in main article with 6 figures; 7 pages in
supplementary materials with 6 figures) in draft mode using the American
Meteorological Society package. Submitted to Journal of Atmospheric Sciences
for publicatio
Detection and evaluation of damage in aircraft composites using electromagnetically coupled inductors
The paper presents a quantitative damage evaluation of carbon-fibre reinforced polymer (CFRP) plates using a non-contact electromagnetic (EM) sensor. The EM sensor with coupled spiral inductors (CSI) is employed here to detect both impact induced and simulated damage leading to an accurate evaluation of the location, depth and width of sub-surface defects. The effect of inspection frequency, standoff distance and signal power are also investigated leading to the development of an engineering circuit design tool that relates the set up and calibration of the sensor to its detection performance. It is found that the dynamic range of the transmission coefficient is the limiting factor in the original Salski CSI sensor and this problem is addressed by adding ferrite layers to reduce the reluctance of the magnetic circuit, improving damage sensing by 22%. The study leads to a further development of utilising an open ferrite yoke with a pair of encircling coils, which shows a 57% sensitivity improvement and clearer identification of air gaps (voids) and delamination in CFRP laminates. The proposed EM yoke design CSI sensor is low cost and could be assembled into an array for non-contact, in situ mechatronic scanning of aircraft composite wings
Usoi Tripura basic vocabulary
The composition of InxGa1 − xN nanorods grown by molecular beam epitaxy with nominal x = 0.5 has been mapped by electron microscopy using Z-contrast imaging and x-ray microanalysis. This shows a coherent and highly strained core-shell structure with a near atomically sharp boundary between a Ga-rich shell (x∼0.3) and an In-rich core (x∼ 0.7), which itself has In- and Ga-rich platelets alternating along the growth axis. It is proposed that the shell and core regions are lateral and vertical growth sectors, with the core structure determined by spinodal decomposition
CD4+ T-cell responses to Epstein-Barr virus (EBV) latent-cycle antigens and the recognition of EBV-transformed lymphoblastoid cell lines
There is considerable interest in the potential of Epstein-Barr virus (EBV) latent antigen-specific CD4 T cells to act as direct effectors controlling EBV-induced B lymphoproliferations. Such activity would require direct CD4 T-cell recognition of latently infected cells through epitopes derived from endogenously expressed viral proteins and presented on the target cell surface in association with HLA class II molecules. It is therefore important to know how often these conditions are met. Here we provide CD4 epitope maps for four EBV nuclear antigens, EBNA1, -2, -3A, and -3C, and establish CD4 T-cell clones against 12 representative epitopes. For each epitope we identify the relevant HLA class II restricting allele and determine the efficiency with which epitope-specific effectors recognize the autologous EBV-transformed B-lymphoblastoid cell line (LCL). The level of recognition measured by gamma interferon release was consistent among clones to the same epitope but varied between epitopes, with values ranging from 0 to 35% of the maximum seen against the epitope peptide-loaded LCL. These epitope-specific differences, also apparent in short-term cytotoxicity and longer-term outgrowth assays on LCL targets, did not relate to the identity of the source antigen and could not be explained by the different functional avidities of the CD4 clones; rather, they appeared to reflect different levels of epitope display at the LCL surface. Thus, while CD4 T-cell responses are detectable against many epitopes in EBV latent proteins, only a minority of these responses are likely to have therapeutic potential as effectors directly recognizing latently infected target cells
Analogue micropower FET techniques review
A detailed introduction to published analogue circuit design techniques using Si and Si/SiGe FET devices for very low-power applications is presented in this review. The topics discussed include sub-threshold operation in FET devices, micro-current mirrors and cascode techniques, voltage level-shifting and class-AB operation, the bulk-drive approach, the floating-gate method, micropower transconductance-capacitance and log-domain filters and strained-channel FET technologies
Impact of the disaster-induced relocation process on the displaced communities in Kegalle district, Sri Lanka
Disaster induced displacement and relocation is a frequently occurring phenomenon in the Sri Lankan context. Resettlement has been recognized as a regular result of disasters such as landslides due to the large-scale property damage that occurs. This paper investigates the impact of the disasterinduced relocation process on displaced communities. The study revolves around the sub-objectives of investigating the various needs of victims in different stages of displacement and how relocation has altered the social, cultural, and livelihood dimensions of the victims. Victims of the Aranayake landslide who were residing in the Kegalle district and who were resettled mainly in a Donor Driven relocation site were selected for the study. A purposive sampling technique was implemented in two phases. In the first phase, in-depth interviews with officials and focus group interviews with community members were carried out. Next, a community needs analysis was conducted with the participation of the community and officials. The data suggests that there is a clear lacuna in strong, written policy frameworks and its practical implementation when satisfying the various needs of displaced communities. Being confined to only understanding the social and economic details of various displaced groups, policy planners have tended to neglect the necessity of conducting a needs analysis with the main reason being the lack of perception of relocation as a long-term process. Therefore, in conclusion, the study suggests a model that addresses the need for a holistic institutional arrangement with further disaster risk management strategies to address the adverse impact on the disaster-induced, displaced community
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