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M Section (m + section)
Selected AbstractsTwo-stage detection of partitioned random CDMAEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2008Lukasz Krzymien Random Code Division Multiple Access (CDMA) with low complexity two-stage joint detection/decoding is considered. A sequence partitioning approach is used for modulation, where every spreading sequence is divided into M sections (partitions) which are interleaved prior to transmission. This setup, called partitioned CDMA, can be understood as a generalisation of (chip) interleave division multiple access (IDMA). An analysis of a low-complexity iterative cancellation receiver is presented for arbitrary received power distributions. It is shown that for equal rate and equal power users the asymptotic performance of partitioned CDMA is equal to the performance of CDMA with optimal a posteriori probability (APP) detection for system loads K/N,<,1.49. Effects of asynchronous signal transmission are quantified for standard pulse shaping filters and it is shown that the signal-to-noise ratios achievable in an asynchronous system are improved with respect to fully synchronous transmission. The effect of unequal received powers is examined and considerable gains in performance are obtained by judicious choices of power distributions. For certain power distribution, partitioned CDMA with iterative detection can achieve arbitrary system loads, that is detection is no longer fundamentally interference limited. The practical near-far resistance of the proposed system is illustrated using an example of a receiver with a circular receive footprint and uniformly distributed transmitters (single cell system). Copyright © 2008 John Wiley & Sons, Ltd. [source] Response of the flora and macroinvertebrate fauna of a chalk stream site to changes in managementFRESHWATER BIOLOGY, Issue 5 2003J. F. Wright SUMMARY 1. Temporal changes in a series of habitats and their macroinvertebrate assemblages were examined on a 50-m section of a chalk stream in Berkshire, England between June 1975,79 and June 1997,2001. 2. The site was part of a trout fishery in 1975,79, when river management included instream weed cutting together with control of bankside trees and riparian vegetation. Management ceased in the 1980s and by 1997,2001, the site was heavily shaded by trees and riparian vegetation. 3. The mean area of instream macrophytes decreased by 50% between the first and second sampling period. In contrast, gravel and silt increased and invading marginal vegetation formed a new habitat. 4. Changes in macroinvertebrate family richness between sampling periods were scale dependant. Although there were, on average, significantly more families in individual replicates in 1975,79 than in 1997,2001, total family richness for the site in each year did not differ significantly between sampling periods. 5. Sixty families of macroinvertebrates were recorded during the study, 50 in both sampling periods, 53 in 1975,79 and 57 in 1997,2001. This small increase in site family richness may be due to the invading marginal plants. 6. Total macroinvertebrate abundance was significantly lower in the second sampling period. A major drought in 1976 resulted in significantly higher densities of macroinvertebrates, partly through the exploitation of epiphytic diatoms by chironomid larvae. A drought in 1997 failed to elicit a similar response because of the limited macrophytes and diatoms under heavy shading by trees and marginal vegetation. 7. Significant increases in important shredders and decreases in some scrapers between the early and later sampling years largely reflected changes in available food resources. 8. Whereas macroinvertebrate family richness has been conserved under the recent ,no management' regime, the site is now less attractive as a fishery because of poor access and lower densities of some macroinvertebrates taken by brown trout. [source] Growth-enhanced fish can be competitive in the wildFUNCTIONAL ECOLOGY, Issue 5 2001J. I. Johnsson Summary 1,The widespread commercial interest in producing growth-enhanced organisms has raised concerns about ecological consequences, emphasizing the need to understand the costs and benefits associated with accelerated growth in nature. Here, sustained-release growth hormone (GH) implants were used to estimate the competitive ability of growth-enhanced fish in the wild. Growth rate, movements and survival over winter were compared between GH-implanted and control Brown Trout in a natural stream. The study was repeated over two consecutive years. 2,GH treatment had no effect on recapture rates, indicating that mortality rates did not differ between GH-treated and control fish. More GH-treated trout (63%) than control fish (41%) were recaptured within their 10 m section of release. Thus, GH-treated fish were more stationary than control fish over winter. 3,GH-treated fish grew about 20% faster than control fish. This was mainly because of a three-fold growth rate increase in GH-treated fish in late summer, whereas growth rates over winter did not differ significantly between treatment groups. These results were consistent over both replicate years. 4,This first study of growth-enhanced fish in the wild shows that they can survive well and therefore may out-compete normal fish with lower growth rates. Although selection against rapid growth may be more intense at other life-history stages and/or during periods of extreme climate conditions, our findings raise concerns that released or escaped growth-enhanced salmonids may compete successfully with resident fish. It is clear that the potential ecological risks associated with growth-enhanced fish should not be ignored. [source] Magnetic polarity stratigraphy of Siwalik Group sediments of Karnali River section in western NepalGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2000Pitambar Gautam The remanent magnetization of siltstones and sandstones sampled at 476 levels/sites throughout a 3560 m thick molasse sequence belonging to the Siwalik Group (0,2015 m: Lower; 2015,3560 m: Middle) has been studied by stepwise thermal demagnetization. This section is exposed along the Karnali River in Nepal. The natural remanent magnetization (NRM) usually consists of two components: a viscous or thermoviscous component of recent field origin, and an ancient characteristic component (ChRM). The former component is of normal polarity and resides either in goethite (unblocking temperature < 150 °C; resistant to AFD up to 150 mT) or in maghemite (unblocking temperature 150,400 °C). Goethite contributes up to 90 per cent of the total intensity in the finer variegated muddy samples belonging to the lower half of the section. Maghemite content is significant in the grey mud-free lithologies from the upper half of the section. The main component, unblocked in the high-temperature range (commonly 610,680 °C) and believed to reside in haematite, presumably of mostly detrital origin, represents a characteristic remanence (ChRM). The tilt-corrected ChRM directions at individual sites show antipodal clusters (ratio of normal- to reverse-polarity sites: 0.62), and yield mean inclinations recording significant inclination shallowing,a feature well recorded in the Siwaliks. This ChRM is interpreted to represent a largely primary detrital remanence. The ChRM data from 430 sites yield the Karnali River magnetic polarity sequence, whose correlation with the geomagnetic polarity timescale (Cande & Kent 1995) suggests a depositional age of 16 Ma (younger than chron C5Cn.1n) to 5.2 Ma (around the top of chron C3r) for the 3560 m section sampled. Hence, the Karnali River exposes the oldest part of the Siwalik Group in Nepal. Estimates of the sediment accumulation rate (SAR) average to 32.9 cm kyr,1 for the 10.8 Myr time span of deposition. [source] Simple non-staining method to demonstrate urate crystals in formalin-fixed, paraffin-embedded skin biopsiesJOURNAL OF CUTANEOUS PATHOLOGY, Issue 5 2009Joshua Weaver Background:, Gouty tophi classically occur as nodules over joints and the helix. The ideal fixative for preservation of gout crystals has traditionally been alcohol because the crystals are formalin and water soluble. However, most biopsies are submitted in formalin fixative, which results in dissolution of urate crystals leaving behind a non-specific pale amorphous area. Although complex staining methods to show urate crystals in tissue have been described, the present study elucidates a simple non-staining method utilizing a thick unstained coverslipped microscopy slide that allows detection and confirmation of birefringence of urate crystals in formalin-fixed, paraffin-embedded tissue. Methods:, Twenty-nine cases of cutaneous gouty tophi were evaluated using a hematoxylin-eosin (H&E)-stained section, a 10-,m unstained coverslipped section and a 4-,m unstained coverslipped section. In all cases, the specimen was received and submitted in formalin. Results:, Polarizable crystals were not identified in any of the H&E sections. The use of the thicker unstained coverslipped section was more sensitive than the standard 4 ,m section by recognizing the characteristic urate crystals in 48% and 38% of the cases, respectively. Conclusions:, This inexpensive adjunctive tool can be used to document gout crystals in almost half of skin biopsies. [source] Delivery of an Adenoviral Vector to the Crushed Recurrent Laryngeal Nerve,THE LARYNGOSCOPE, Issue 6 2003Adam Rubin MD Abstract Objectives Objectives were to create a model of recurrent laryngeal nerve injury for testing the efficacy of potential therapeutic viral gene therapy vectors and to demonstrate that remote injection of a viral vector does not cause significant additional neuronal injury. Study Design Animal model. Methods Rats were randomly assigned to three groups of 10 animals each. In group I, the recurrent laryngeal nerve was crushed. In group II, the nerve was crushed and then injected with an adenoviral vector containing no transgene. In group III, the nerve was identified but was not crushed. Rats were killed at 1 week, and their larynges and brainstems were cryosectioned in 15-,m sections. Laryngeal cryosections were processed for acetylcholine histochemical analysis (motor endplates) followed by neurofilament immunoperoxidase (nerve fibers). Percentage of nerve,endplate contact was determined and compared between groups. Fluorescent in situ hybridization was performed on brainstem sections from rats in group II to confirm the presence of virus. Results No significant difference in percentage of nerve,endplate contact exists between the two crushed-nerve groups (groups I and II) (P = .88). The difference between both crushed-nerve groups and the group with noncrushed nerves (group III) was highly significant (P <.0001). The presence of virus was confirmed in group II rats. Conclusions Crush provides a significant measurable injury to the recurrent laryngeal nerve and may be used as a model to explore therapeutic interventions for nerve injury. The remote injection of viral vector did not cause significant additional neuronal injury. Remote delivery of viral vectors to the central nervous system holds promise in the treatment of recurrent laryngeal nerve injury and central nervous system diseases. [source] Small nerve fiber involvement in systemic lupus erythematosus: A controlled studyARTHRITIS & RHEUMATISM, Issue 5 2002Roald Omdal Objective To determine if patients with systemic lupus erythematosus (SLE) may have a peripheral neuropathy involving unmyelinated and small, myelinated nerve fibers, by immunostaining epidermal nerve fibers (ENF) in skin biopsy samples for the panaxonal marker, protein gene product 9.5 (PGP 9.5). Methods Fifteen consecutive and nonselected SLE patients and 15 age- and sex-matched controls were included in the study. The age of the patients ranged from 25 years to 65 years, with a mean ± SD age of 47.3 ± 10.2 years and a disease duration of 2,28 years (mean ± SD 14.8 ± 8.6 years). Two 3-mm skin biopsy samples were obtained with a punch needle ,10 cm superior to the lateral malleolus of the right leg and immunostained with 0.1% rabbit polyclonal antibodies to human PGP 9.5. The number of ENF per millimeter was counted and recorded as the mean ± SD of counts in six 50-,m sections, 3 from each of the 2 biopsy samples. Results The mean number of ENF per mm in patients with SLE was 8.0 ± 1.5 (range 5.0,9.9), while the matched controls had 12.2 ± 3.8 ENF per mm (range 6.8,18.6) (P = 0.0006). Conclusion This study indicates that a small fiber involvement in patients with SLE may be responsible for the prevalent neuropathic symptoms and impaired warm sense that is observed in such patients. [source] Effects of cadmium on formation of the ventral body wall in chick embryos and their prevention by zinc pretreatmentBIRTH DEFECTS RESEARCH, Issue 2 2001Jennifer Thompson Background Cadmium (Cd) is an established experimental teratogen whose effects can be reversed by pretreatment with zinc. Mesodermal development is a frequently reported target for Cd teratogenicity. The aim of this study was to examine the mechanisms of Cd induced body wall defects in chick embryos. Methods Chick embryos in shell-less culture were treated with 50 ,l of cadmium acetate (8.9 × 10,5 M Cd2+) at 60-hr incubation (H.-H. stages 16,17). Controls received equimolar sodium acetate. Other embryos were treated with various concentrations of zinc acetate and then with Cd or NaAc 1 hrs later. Development was evaluated 48 hrs later. Resin-embedded 1-,m sections were examined at earlier stages. Results Cd caused embryolethality (35%), ventral body wall defect with malpositioned lower limbs (40%), and weight reduction in survivors. After 4-hr treatment with Cd, breakdown of junctions between peridermal cells with rounding up and desquamation occurred. Shape changes were also seen in the basal layer of the ectoderm. At 4 hr, cell death was evident in lateral plate mesoderm, somites, and neuroepithelium; the lateral plate mesoderm began to grow dorsally, carrying the attached limb buds with it. Zn pretreatment protected against the lethal, teratogenic, and growth-retarding effects of Cd, as well as ectodermal changes and cell death. Conclusions Cd disrupts peridermal cell adhesion and induces cell death in the mesoderm. This may result in abnormal growth of lateral plate mesoderm and in a body wall defect. Zn pretreatment prevents both the gross teratogenic effects and the cellular changes, most likely by competition with Cd. Teratology 64:87,97, 2001. © 2001 Wiley-Liss, Inc. [source] | |||||||||||||