15 research outputs found
Advances in UWB-based Indoor Position Estimation and its Application in Fall Detection
In an indoor propagation environment, the position of an Object of
Interest (OOI) is typically estimated by cleverly manipulating range
or proximity measurements that are obtained from a series of reference
node combinations. In a noise-free propagation scenario, these
measured parameters are fed into conventional position estimation
techniques and an accurate estimate of the OOIās position is obtained.
In practice, the propagation scenario is never quite noise-free; hence
the OOIās position estimate is obtained in error. Ultra-Wideband
(UWB) is a wireless communication technology that is able to resolve
individual multipath components and this ensures that it is capable
of estimating the arrival time of the first signal path. The implication
of this lies in the fact that the accuracy of the range or proximity
measurements obtained from the reference node combinations is guaranteed;
hence leading to a reliable estimate of the OOIās position.
In the research work presented in this thesis, the body of knowledge
that relates to indoor position estimation is advanced upon. With a
primary focus of enhancing the estimation accuracy of indoor position
estimation systems, UWB is utilised as the underlying wireless
communications technology. The challenges faced by current UWBbased
position estimation systems are identified and tackled directly.
Specifically, the position estimation error that is due to multipath
propagation is addressed and a pre-localisation algorithm that serves
the purpose of resolving individual multipath UWB signals in the
immediate environment is proposed.
Additionally, a novel position estimation technique coined as Time
Reflection of Arrival (TROA) is presented in this thesis. Through a
series of Mean Squared Error (MSE) and CramĀ“er-Rao Lower Bound
(CRLB) analyses, TROA is shown to be very effective when compared
to TOA and the typically unvoiced TSOA technique. In the last section
of this thesis, an application of UWB in the area of Biomedical
Engineering is demonstrated. Specifically, UWB-based position estimation
is used to define a novel fall detection algorithm tailored for
Dementia patients
Ultra-wideband-based multilateration technique for indoor localisation
In this study, the authors present a novel geometrically driven multilateration technique that is based on ultra-wideband (UWB) technology. The authors refer to their proposed solution as time reflection of arrival (TROA). They demonstrate in this study how the position estimation error is improved upon by carefully considering the inherent properties of the UWB technology and the reflection properties of transmitted UWB signals. By a direct comparison between TROA and two widely used multilateration techniques, the authors show that indoor position estimation can be done much more effectively using their proposed solution. They also derive a new CramĆ©rāRao lower bound for TROA multilateration and use it to show its level of efficiency
Polymorphisms in MGP gene and their association with lead toxicity
Matrix Ī³-carboxy glutamic acid protein (MGP) is a 10-kDa secreted protein containing five residues of the vitamin K-dependent calcium binding amino acid Ī³-carboxyglutamic acid (Gla). This study was carried out to examine the effects of MGP gene promoter polymorphism (T-138C) on blood lead levels (BLL) and hematological parameters in 113 battery manufacturing unit workers occupationally exposed to lead and 102 controls. Genotypes for the MGP T-138C polymorphism were determined by PCR and restriction fragment length digestion. BLL were determined by Anode Stripping Voltammetry using ESA Model 3010B Lead analyzer. Complete blood picture (CBP) was analyzed using ADVIA Cell counter for each sample. The frequencies of MGPāTT, CT and CC genotypes in our population were 38.6%, 44.3%, and 17.2%, respectively. The frequencies for T and C alleles were 0.612 and 0.386, respectively. Although BLL did not differ significantly among genotypes; they were higher in workers with TT/CT genotype compared to CC genotype subjects (76ā88 Ī¼g/dL vs 22ā45 Ī¼g/dL, p > 0.05). About 29.2% of volunteers (n = 33) from the occupationally exposed group had hemoglobin levels below 10.0 gms/dl. There was no significant difference in total white cell count and platelet count between occupational and non-exposed groups. The possible role of SNPs in the promoter region of MGP gene with relation to lead toxicity was investigated for the first time in the Indian population; although significance could not be achieved in this study, further assessments over a larger population size may help in better understanding of the consequences of lead exposure
HFE Gene Variants Modify the Association between Maternal Lead Burden and Infant Birthweight: A Prospective Birth Cohort Study in Mexico City, Mexico
<p>Abstract</p> <p>Background</p> <p>Neonatal growth is a complex process involving genetic and environmental factors. Polymorphisms in the hemochromatosis (<it>HFE</it>) iron regulatory genes have been shown to modify transport and toxicity of lead which is known to affect birth weight.</p> <p>Methods</p> <p>We investigated the role of <it>HFE C282Y</it>, <it>HFE H63 D</it>, and transferrin <it>(TF) P570 S </it>gene variants in modifying the association of lead and infant birthweight in a cohort of Mexican mother-infant pairs. Subjects were initially recruited between 1994-1995 from three maternity hospitals in Mexico City and 411 infants/565 mothers had archived blood available for genotyping. Multiple linear regression models, stratified by either maternal/infant <it>HFE </it>or <it>TF </it>genotype and then combined with interaction terms, were constructed examining the association of lead and birthweight after controlling for covariates.</p> <p>Results</p> <p>3.1%, 16.8% and 17.5% of infants (N = 390) and 1.9%, 14.5% and 18.9% of mothers (N = 533) carried the <it>HFE C282Y</it>, <it>HFE H63D</it>, and <it>TF P570 S </it>variants, respectively. The presence of infant <it>HFE H63 D </it>variants predicted 110.3 g (95% CI -216.1, -4.6) decreases in birthweight while maternal <it>HFE H63 D </it>variants predicted reductions of 52.0 g (95% CI -147.3 to 43.2). Interaction models suggest that both maternal and infant <it>HFE H63 D </it>genotype may modify tibia lead's effect on infant birthweight in opposing ways. In our interaction models, maternal <it>HFE H63 D </it>variant carriers had a negative association between tibia lead and birthweight.</p> <p>Conclusions</p> <p>These results suggest that the <it>HFE H63 D </it>genotype modifies lead's effects on infant birthweight in a complex fashion that may reflect maternal-fetal interactions with respect to the metabolism and transport of metals.</p
Oksidacijski stres u lakirera izloženih niskim razinama olova
Lead toxicity is a public health problem particularly to the children and to occupationally exposed adults. Evidence is mounting successively regarding the adverse health effects of lead at low levels. This study was undertaken to assess the antioxidant status of lead-exposed residential and commercial painters of Lucknow city in Uttar Pradesh, India. Thirty-five painters aged 20 to 50 years who had blood lead levels ā¤400 Āµg L-1 were selected for the study from a population of 56 male painters initially screened for blood lead. The control group included an equal number of subjects of the same age group without any occupational exposure to lead. We studied the association between low lead level exposure and antioxidant status and found that blood lead levels in painters were approximately seven times as high as in controls [(219.2 Ā± 61.9) Āµg L-1 vs. (30.6Ā±10.1) Āµg L-1, respectively]. Among the biomarkers of lead toxicity a significant decrease in the level of delta-aminolevulinic acid dehydratase [(9.13Ā±4.62) UL-1 vs. (39.38Ā±5.05) UL-1] and an increase in the level of zinc protoporphyrin [(187.9Ā±49.8) Āµg L-1 vs. (26.4Ā±5.5) Āµg L-1] were observed in painters compared to controls. Among antioxidant enzymes, painters showed a significant decrease in catalase [(56.77Ā±11.11) UL-1 vs. (230.30Ā±42.55) UL-1] and superoxide dismutase [(0.64Ā±0.19) UL-1 vs. (2.68Ā±0.62) UL-1] compared to controls. Lipid peroxidation was monitored by measuring thiobarbituric acid reactive substances (TBARS) that were expressed in terms of malondialdehyde (MDA) equivalents. Concentration of MDA in plasma was higher in painters than in controls [(7.48Ā±1.31) nmol mL-1 vs. (3.08Ā±0.56) nmol mL-1]. Significant changes were also observed in reduced and oxidised glutathione levels. The strong association between blood lead levels and oxidative stress markers in this population suggests that oxidative stress should be considered in the pathogenesis of lead-related diseases among people with low level environmental exposure to lead.ToksiÄnost olova javnozdravstveni je problem, napose u djece i odraslih osoba koje su im izložene profesionalno. Sve je viÅ”e dokaza o Å”tetnom djelovanju olova pri niskim razinama. Svrha je ovog ispitivanja bila procijeniti antioksidacijski status u lakirera iz grada Lucknowa u indijskoj pokrajini Uttar Pradesh. Iz skupine od 56 muÅ”karaca lakirera u dobi od 20 do 50 godina s pozitivnim poÄetnim nalazima olova u krvi, za ispitivanje su izabrana 35-orica Äije su razine iznosile ā¤400 Āµg L-1. Izabran je i jednaki broj kontrolnih ispitanika iz iste dobne skupine, koji nisu bili profesionalno izloženi olovu. Ispitana je povezanost izme|u izloženosti niskim razinama olova i antioksidacijskoga stanja te je utvrÄeno da su razine olova u krvi lakirera [(219,2Ā±61,9) Āµg L-1] bile oko sedam puta viÅ”e negoli u kontrolnih ispitanika [(30,6Ā±10,1) Āµg L-1]. Od biopokazatelja toksiÄnosti olova u lakirera je zamijeÄen znaÄajan pad razina delta- ALAD [(9,13Ā±4,62) UL-1 prema (39,38Ā±5,05) UL-1] te rast razina cinkova protoporfirina [(187,9Ā±49,8) Āµg L-1 prema (26,4Ā±5,5) Āµg L-1] u odnosu na kontrolne ispitanike. Od antioksidacijskih enzima u lakirera je znaÄajno pala aktivnost katalaze [(56,77Ā±11,11) UL-1 prema (230,30Ā±42,55) UL-1] i superoksid dismutaze [(0,64Ā±0.19) UL-1 prema (2,68Ā±0,62) UL-1] u odnosu na kontrolu, dok je produkt lipidne peroksidacije u plazmi (izv. thiobarbituric acid reactive substances, TBARS) izražen kao koncentracija malondialdehida (MDA) porastao [(7,48Ā±1,31) nmol mL-1 prema (3,08Ā±0,56) nmol mL-1]. ZnaÄajne su promjene takoÄer zamijeÄene u smanjenim razinama glutationa i njihovoj oksidaciji. Snažna povezanost razina olova u krvi s pokazateljima oksidacijskoga stresa upuÄuje na to da u osoba s niskom razinom izloženosti olovu iz okoliÅ”a kod razmatranja patogeneze bolesti povezane s olovom u obzir valja uzeti oksidacijski stres