163 research outputs found
Short-term air pollution forecasting based on environmental factors and deep learning models
No full textThe effects of air pollution on people, the environment, and the global economy are profound - and often under-recognized. Air pollution is becoming a global problem. Urban areas have dense populations and a high concentration of emission sources: vehicles, buildings, industrial activity, waste, and wastewater. Tackling air pollution is an immediate problem in developing countries, such as North Macedonia, especially in larger urban areas. This paper exploits Recurrent Neural Network (RNN) models with Long Short-Term Memory units to predict the level of PM10 particles in the near future (+3 hours), measured with sensors deployed in different locations in the city of Skopje. Historical air quality measurements data were used to train the models. In order to capture the relation of air pollution and seasonal changes in meteorological conditions, we introduced temperature and humidity data to improve the performance. The accuracy of the models is compared to PM10 concentration forecast using an Autoregressive Integrated Moving Average (ARIMA) model. The obtained results show that specific deep learning models consistently outperform the ARIMA model, particularly when combining meteorological and air pollution historical data. The benefit of the proposed models for reliable predictions of only 0.01 MSE could facilitate preemptive actions to reduce air pollution, such as temporarily shutting main polluters, or issuing warnings so the citizens can go to a safer environment and minimize exposure
Multi-horizon air pollution forecasting with deep neural networks
No full textAir pollution is a global problem, especially in urban areas where the population density is very high due to the diverse pollutant sources such as vehicles, industrial plants, buildings, and waste. North Macedonia, as a developing country, has a serious problem with air pollution. The problem is highly present in its capital city, Skopje, where air pollution places it consistently within the top 10 cities in the world during the winter months. In this work, we propose using Recurrent Neural Network (RNN) models with long short-term memory units to predict the level of PM10 particles at 6, 12, and 24 h in the future. We employ historical air quality measurement data from sensors placed at multiple locations in Skopje and meteorological conditions such as temperature and humidity. We compare different deep learning models’ performance to an Auto-regressive Integrated Moving Average (ARIMA) model. The obtained results show that the proposed models consistently outperform the baseline model and can be successfully employed for air pollution prediction. Ultimately, we demonstrate that these models can help decision-makers and local authorities better manage the air pollution consequences by taking proactive measures
Specific mechanical properties of superplastically formed components and resulting applications for vehicles
No full textThe technical requirements to produce parts as light as possible with more complex geometries are ever increasing in recent years in automotive industries, rail vehicle and aerospace. Manufacturing technologies such as super-plastic metal forming, which had been considered as a niche technology earlier, is now gaining greater technical relevance for industrial size production. The parts that have been generated through super-plastic forming in innovative vehicle for example Mercedes SLS AMG reflect the industrial activity in this area. Manufacturability of thin-walled structures enables lightweight design. Also the tool and manufacturing costs are lower in comparison. However, the main challenge could be found in maintaining exact process parameters. There is a large research potential in super-plastic forming; from the determination of optimal material data through process simulation to manufacturing of real parts and their characterization. In the framework of the project international Bureau of the Federal Ministry of Education and Research UKR005/08 “Manufacture of parts with special properties” a preliminary research work has been carried out.
The scientific challenge lies in the characterisation of forming properties of light metal alloys in super-plastic forming. In this preliminary research, the “full factorial experiment” methodology has been applied, regression equations have been developed and a mathematical model derived. This shows interrelationship between mechanical properties of the material and the variable process parameters, leading to material characterization. Hence advantages of cost and time have been achieved; the important parameters for the design of parts through super-plastic forming are determined. The analytical results are then verified with finite element method ─ simulations and through experiments with general parts
Factor V Leiden Is Associated with Higher Risk of Deep Venous Thrombosis of Large Blood Vessels
No full textAim: To determine the prevalence of factor V Leiden mutation in patients with different presentation of venous thromboembolic disease and healthy individuals in the Republic of Macedonia.
Methods: The retrospective study involved 190 patients with venous thromboembolic disease and 200 healthy individuals, who were screened for the presence of factor V Leiden mutation with a polymerase chain reaction-restriction fragment length polymorphism method. The prevalence of factor V Leiden was analyzed according to the localization of thrombosis, presence of risk factors, and family history of thrombosis. The odds of deep venous thrombosis were calculated with respect to the presence of factor V Leiden mutation.
Results: The prevalence of factor V Leiden mutation among patients with venous thromboembolic disease was 21.1%, compared with 5.5% in the healthy individuals. Factor V Leiden positive patients had the first episode of deep venous thrombosis at a younger age, and the prevalence of the mutation was the highest among patients with a positive family history of thrombosis (33.9%, P=0.003) and in patients with deep venous thrombosis affecting a large blood vessel (37.7%, P=0.001). The prevalence of factor V Leiden mutation was lower in patients with calf deep venous thrombosis and primary thromboembolism (13.3% and 13.1%, respectively; P>0.05). The odds ratio for iliofemoral or femoral deep venous thrombosis in factor V Leiden carriers was 10.4 (95% confidence interval, 4.7-23.1).
Conclusion: The prevalence of factor V Leiden mutation was high in both patients with venous thromboembolic disease and healthy individuals in Republic of Macedonia. Factor V Leiden carriers have the highest odds of developing deep venous thrombosis affecting a large venous blood vessel
The prospective randomized study of the safety and efficacy of surgical revascularization of myocardium after carotid stent implantation versus simultaneous carotid and coronary surgical revascularization
No full textИнциденца тешке каротидне болести у пацијената који се подвргавају
операцији реваскуларизације срца је у распону од 6-12%. У ових пацијената постоји
три пута већи ризик од неуролошких компликација након миокардне
реваскуларизације, чак и у случајевима асимптоматске каротидне болести. И поред
присутних доказа о комплексности и озбиљности комбиноване каротидне и
коронарне болести, оптималан третман је и даље контроверзан. Два протокола се
најчешће користе: каротидно стентирање или ендартеректомија која претходи
реваскуларизацији срца 2-4 недеље или, симултана интервенција. Ниједна од ових
опција није показала супериорност, а, за сада, не постоје ни рандомизоване студије
који би дале одговор на то питање. Код временски раздвојених интервенција где се
примарно лечи каротидна болест, ризик од акутног инфаркта миокарда пре срчане
операције је висок, уколико је у питању каротидна ендартеректомија, док у
стентирању постоји већи ризик од неуролошких компликација. С друге стране,
симултана операција је повезана са повишеним периоперативним морбидитетом и
морталитетом. Код симултане хируршке реваскуларизације, и поред елиминисања
међу-процедуралног ризика, резултати су слични хируршкој интервенцији у два
времена, а у многим студијама су инфериорнији у односу на резултате каротидног
стентирања и коронарног премошћавања када се изводи одвојено, углавном, због
високог ризика од периоперативног шлога. Однедавно, доступни су подаци о
четвртој опцији- симултано каротидно стентирање и миокардна реваскуларизација.
Све серије су нерандомизоване, већина је ретроспективна, а све су лимитиране
малим бројем пацијената и имају различите пери и постпроцедуралне протоколе.
Ова студија је проспективна, рандомизована, а њен циљ је поређење раних и
средњорочних резултата симултане хибридне реваскуларизације (каротидно
стентирање и миокардна реваскуларизација) са хируршком комбинованом
каротидном ендартеректомијом и коронарном операцијом...The prevalence of severe carotid artery disease among patients undergoing
coronary artery bypass surgery (CABG) is estimated to be 6-12%. These patients have
three-fold higher risk for neurological complications after CABG, even if the carotid
artery disease is asymptomatic.
Despite the acknowledgment of its significance, treatment options for the
significant carotid artery disease in the patient undergoing CABG remain controversial.
Overall, two protocols are widely used: staged procedure, with carotid artery stenting
(CAS) or carotid eversion endarterectomy (CEA) followed by CABG (2-4 weeks later),
and simultaneous CAS/CEA with CABG. However, either of these proved not to be
superior. Moreover, there have been no randomized trials aiming to assess properly
which strategy is more appropriate. In the staged surgical approach that addresses the
carotid artery lesion first, the risk of acute myocardial infarction prior to CABG is rather
high when performing CEA while the risk of stroke is increased in patients undergoing
CAS. On the other hand, the combined surgical approach is associated with an increased
risk of both cerebral and cardiac mortality and morbidity. With combined CEA/CABG,
despite eliminating inter-stage risk, outcomes have been similar to staged CEA/CABG
and in many studies inferior to the staged CAS/CABG, mainly due to higher operative
stroke risk.
Recently, more data are available for the fourth option - the simultaneous,
combined approach of CAS and CABG. All published series were nonrandomized, most
were retrospective, and all with limited number of patients, as well as with different periand
postprocedural protocols. We performed prospective, randomized study with an aim
to compare the early postprocedural results of simultaneous hybrid CAS and coronary
bypass surgery vs. concomitant CEA – CABG procedure..
A 4D tomographic ionospheric model to support PPP-RTK
No full textSuccessful implementation of integer ambiguity resolution enabled precise point positioning (aka PPP-RTK) algorithms is inextricably linked to the ability of a user to perform near real-time positioning by quickly and reliably resolving the integer carrier-phase ambiguities. In the PPP-RTK technique, a major barrier to successful ambiguity resolution is the unmodelled impact of the ionosphere. We present a 4D ionospheric tomographic model that computes in real time the ionospheric electron density as a linear combination of basis functions, namely B-splines. The results show that when the ionospheric estimates are provided as atmospheric corrections for a PPP-RTK end-user, the time to fix its horizontal position below 10 cm is around 20 epochs (the sample rate is 30 s) at the 90 % of the cumulative distribution function (CDF), as opposed to the time it takes when no external corrections are provided, which is around 80 epochs at 90 % of the CDF.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Mathematical Geodesy and Positionin
The prospective randomized study of the safety and efficacy of surgical revascularization of myocardium after carotid stent implantation versus simultaneous carotid and coronary surgical revascularization
No full textИнциденца тешке каротидне болести у пацијената који се подвргавају
операцији реваскуларизације срца је у распону од 6-12%. У ових пацијената постоји
три пута већи ризик од неуролошких компликација након миокардне
реваскуларизације, чак и у случајевима асимптоматске каротидне болести. И поред
присутних доказа о комплексности и озбиљности комбиноване каротидне и
коронарне болести, оптималан третман је и даље контроверзан. Два протокола се
најчешће користе: каротидно стентирање или ендартеректомија која претходи
реваскуларизацији срца 2-4 недеље или, симултана интервенција. Ниједна од ових
опција није показала супериорност, а, за сада, не постоје ни рандомизоване студије
који би дале одговор на то питање. Код временски раздвојених интервенција где се
примарно лечи каротидна болест, ризик од акутног инфаркта миокарда пре срчане
операције је висок, уколико је у питању каротидна ендартеректомија, док у
стентирању постоји већи ризик од неуролошких компликација. С друге стране,
симултана операција је повезана са повишеним периоперативним морбидитетом и
морталитетом. Код симултане хируршке реваскуларизације, и поред елиминисања
међу-процедуралног ризика, резултати су слични хируршкој интервенцији у два
времена, а у многим студијама су инфериорнији у односу на резултате каротидног
стентирања и коронарног премошћавања када се изводи одвојено, углавном, због
високог ризика од периоперативног шлога. Однедавно, доступни су подаци о
четвртој опцији- симултано каротидно стентирање и миокардна реваскуларизација.
Све серије су нерандомизоване, већина је ретроспективна, а све су лимитиране
малим бројем пацијената и имају различите пери и постпроцедуралне протоколе.
Ова студија је проспективна, рандомизована, а њен циљ је поређење раних и
средњорочних резултата симултане хибридне реваскуларизације (каротидно
стентирање и миокардна реваскуларизација) са хируршком комбинованом
каротидном ендартеректомијом и коронарном операцијом...The prevalence of severe carotid artery disease among patients undergoing
coronary artery bypass surgery (CABG) is estimated to be 6-12%. These patients have
three-fold higher risk for neurological complications after CABG, even if the carotid
artery disease is asymptomatic.
Despite the acknowledgment of its significance, treatment options for the
significant carotid artery disease in the patient undergoing CABG remain controversial.
Overall, two protocols are widely used: staged procedure, with carotid artery stenting
(CAS) or carotid eversion endarterectomy (CEA) followed by CABG (2-4 weeks later),
and simultaneous CAS/CEA with CABG. However, either of these proved not to be
superior. Moreover, there have been no randomized trials aiming to assess properly
which strategy is more appropriate. In the staged surgical approach that addresses the
carotid artery lesion first, the risk of acute myocardial infarction prior to CABG is rather
high when performing CEA while the risk of stroke is increased in patients undergoing
CAS. On the other hand, the combined surgical approach is associated with an increased
risk of both cerebral and cardiac mortality and morbidity. With combined CEA/CABG,
despite eliminating inter-stage risk, outcomes have been similar to staged CEA/CABG
and in many studies inferior to the staged CAS/CABG, mainly due to higher operative
stroke risk.
Recently, more data are available for the fourth option - the simultaneous,
combined approach of CAS and CABG. All published series were nonrandomized, most
were retrospective, and all with limited number of patients, as well as with different periand
postprocedural protocols. We performed prospective, randomized study with an aim
to compare the early postprocedural results of simultaneous hybrid CAS and coronary
bypass surgery vs. concomitant CEA – CABG procedure..
Ellipsometric study of passive and anodic oxide films formed on Ti and Nb electrodes
No full textElectrochemical formation of passive films and active/passive transition on Ti and Nb metal surfaces in various concentrations of H2SO4 and KOH solutions was investigated using potentiostatic and cyclic voltammetry methods. By simultaneous electrochemical and in-situ ellipsometric measurements the coefficients of film thickness growth of passive films in the potential region from -1.5 V to 4 V were determined. Results indicate the strong influence of the concentration and electrolyte nature to the active/passive transitions and stability of passive films. The influence of cathodic pre-treatment on the passive films dissolution and appearance of the reactivation peaks during the reverse potential cycling were shown. By multiple cycle sequences in which the final anodic potential was gradually enlarged, the barrier properties of passive films on investigated electrodes were confirmed. The electrochemical and ellipsometric data showed that the passive films formed on Nb electrode are more resistant that passive films formed on Ti electrode, especially in higher concentrations of investigated aggressive solutions
In vitro induction of organogenesis and genetic transformation of cannabis (Cannabis sativa)
No full textVzpostavili smo uspešen protokol za gensko transformacijo konoplje (Cannabis sativa
L.). Za določitev protokola za adventivno regeneracijo konoplje smo izvedli več
poskusov. Najprej smo preizkusili različne regenerativne sposobnosti treh tipov
izsečkov (listnih pecljev, listnih izsečkov in internodijev) ter njihov potencial za tvorbo
kalusa. Raziskan je bil tudi učinek osnovnih gojišč DKW (Driver in Kuniyuki, 1984) in
MS (Murashige in Skoog, 1962). Predmet raziskave je bil tudi vpliv svetlobnega režima
na regenerativni potencial listnih pecljev in organogenetski potencial šestih genotipov
konoplje za uporabo v medicinske namene ter ene industrijske sorte konoplje.
Proučevan je bil tudi vpliv različnih koncentracij fitohormonov, kot so tidiazuron
(TDZ), 6-benzilaminopurin (BAP) in 1-naftalenocetna kislina (NAA), da bi našli najbolj
obetavno kombinacijo za razvoj kalusa in poganjkov. Listni peclji genotipa BF.KEM1.2
so imeli večji potencial za razvoj kalusa in poganjkov v primerjavi z drugima dvema
tipoma izsečkov. Vzpostavljena je bila adventivna regeneracija netransformiranih
poganjkov s 5 % uspešnostjo iz listnih pecljev genotipa BF.KEM3 na gojišču DKW z
0,2 mg/l TDZ, 0,5 mg/l NAA in 0,1 μM/l peptida fitosulfokin (PSK). Prisotnost svetlobe
je pozitivno vplivala na razvoj poganjkov in kalusa. Nadalje smo listne peclje iz
genotipa BF.KEM3 transformirali s kokultivacijo z bakterijo Agrobacterium
tumefaciens, ki je vsebovala plazmid pCAMBIA1302-ZsGreen, ki vsebuje v svoji regiji
T-DNA selekcijski gen hptII in reporterski gen ZsGreen. Prisotnost reporterskega gena
ZsGreen smo preverili z detekcijo zelene fluorescence in verižno reakcijo s polimerazo
(PCR) ter ga potrdili v 95 % pregledanih transformiranih kalusnih skupkih, prisotnost
gena hptII pa smo potrdili s PCR pri 85 % pregledanih transformiranih kalusnih skupkih.We have established a successful protocol for the genetic transformation of cannabis (C.
sativa L.). More stages of research were performed to establish the protocol for
adventitious regeneration of cannabis. We have first tested the different regenerative
potentials of three explant types (petioles, leaf cuttings, and internodes), and their
potential to produce callus. The effect of the DKW (Driver in Kuniyuki, 1984), and MS
(Murashige in Skoog, 1962) basic media was also explored. The influence of the light
regime on the regenerative potential of petioles, and the organogenetic potential of 6
medicinal genotypes one industrial cultivar of cannabis was also the subject of research.
The different concentrations of phytohormones thidiazurone (TDZ), 6-
benzylaminopurine (BAP), and 1-naphtaleneacetic acid (NAA), were also investigated
to find the most promising combination for callus production and shoot development.
Petioles from the BF.KEM1.2 genotype, showed the highest potential for callus and
shoots development compared with the other two explant types. Adventitious
regeneration of non-transformed shoots was also successfully established, with a 5%
rate of success, from the petioles of the BF.KEM3 genotype, on the DKW medium
supplemented with 0,2 mg/l of TDZ, 0,5 mg/l of NAA, and 0,1 μM/l of the
phytosulfokine (PSK) peptide. The presence of light positively influenced the shoots
and callus development. Furtherly, petioles from the genotype BF.KEM3 were
transformed by co-cultivation with Agrobacterium tumefaciens, which was carrying the
pCAMBIA1302-ZsGreen plasmid, which contains in its T-DNA region selection gene
hptII and reporter gene ZsGreen. We have confirmed the presence of the ZsGreen
reporter gene in 95 % of the examined transformed calli and the presence of the hptII
gene was confirmed in 85 % of the examined transformed calli
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