On Wheeler's delayed-choice Gedankenexperiment and its laboratory realization

Here, we present an analysis and interpretation of the experiment performed by Jacques et al. (2007 Science 315, 966), which represents a realization of Wheeler's delayed-choice Gedankenexperiment. Our analysis is based on the evolution of the photon state, since the photon enters into the Mach-Zehnder interferometer with a removable beam-splitter until it exits. Given the same incident photon state onto the output beam-splitter, BS_output, the photon's state at the exit will be very different depending on whether BS_output is on or off. Hence, the statistics of photon counts collected by the two detectors, positioned along orthogonal directions at the exit of the interferometer, is also going to be very different in either case. Therefore, it is not that the choice of inserting (on) or removing (off) a beam-splitter leads to a delayed influence on the photon behavior before arriving at the beam-splitter, but that such a choice influences the photon state at and after BS_output, i.e., after it has exited from the Mach-Zehnder interferometer. The random on/off choice at BS_output has no delayed effect on the photon to behave as a wave or a corpuscle at the entrance and inside the interferometer, but influences the subsequent evolution of the photon state incident onto BS_output.Comment: 7 pages, 4 figure

Coherence loss and revivals in atomic interferometry: A quantum-recoil analysis

The coherence effects induced by external photons coupled to matter waves inside a Mach-Zehnder three-grating interferometer are analyzed. Alternatively to atom-photon entanglement scenarios, the model considered here only relies on the atomic wave function and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. A good quantitative agreement is found when comparing the results obtained from our model with the experimental data.Comment: 18 pages, 4 figure

Coherence loss and revivals in atomic interferometry: A quantum-recoil analysis

The coherence effects induced by external photons coupled to matter waves inside a MachZehnder three-grating interferometer are analyzed. Alternatively to atomphoton entanglement scenarios, the model considered here only relies on the atomic wavefunction and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. Good quantitative agreement is found when comparing the results obtained from our model with the experimental data. © 2012 IOP Publishing Ltd.MD, MB and DA acknowledge support from the Ministry of Science of Serbia under Projects OI171005, OI171028 and III45016. ASS acknowledges support from the Ministerio de Econom´ıa y Competitividad (Spain) under Projects FIS2010-22082 and FIS2010-29596-C02-01, as well as for a “Ram´on y Cajal” Research Fellowship.Peer Reviewe

The influence of powder particle size on properties of Cu-Al2O3 composites

Inert gas atomized prealloyed copper powder containing 2 wt.% Al (average particle size ≈ 30 μm) and a mixture consisting of copper (average particle sizes ≈ 15 μm and 30 μm) and 4 wt.% of commercial Al2O3 powder particles (average particle size ≈ 0.75 μm) were milled separately in a high-energy planetary ball mill up to 20 h in air. Milling was performed in order to strengthen the copper matrix by grain size refinement and Al2O3 particles. Milling in air of prealloyed copper powder promoted formation of finely dispersed nano-sized Al2O3 particles by internal oxidation. On the other side, composite powders with commercial micro-sized Al2O3 particles were obtained by mechanical alloying. Following milling, powders were treated in hydrogen at 400 0C for 1h in order to eliminate copper oxides formed on their surface during milling. Hot-pressing (800 0C for 3 h in argon at pressure of 35 MPa) was used for compaction of milled powders. Hot-pressed composite compacts processed from 5 and 20 h milled powders were additionally subjected to high temperature exposure (800°C for 1 and 5h in argon) in order to examine their thermal stability. The results were discussed in terms of the effects of different size of starting powders, the grain size refinement and different size of Al2O3 particles on strengthening, thermal stability and electrical conductivity of copper-based composites

Kratkoročna prognoza potrošnje električne energije zasnovana na metodama veštačke inteligencije

The topic of this dissertation is a short-term load forecasting using artificial intelligence methods. Three new models with least squares support vector machines for nonlinear regression are proposed. First proposed model is a model with forecasting in two stages. This model use additioal feature, maximum daily load which is not known for day ahead. Forecating of maximum daily load is obtained in the first stage. This forecasted value is used in second stage, where forecasting of hourly load is done. Model with feature selection, using mutual information for selection criteria, is a second proposed model. This model tries to find an optimal feature set for a given problem. Forecasting model based on an incremental update scheme is a third proposed model. This model is based on the incremental update of the initial training set by adding new instances into it as soon as they become available and throwing out the old ones. Then the model is trained with new training set. By this approach the evolving nature of the load pattern is followed and the model performance is preserved and improved. For models evaluation, the forecasting of hourly loads for one year is done. Electrical consumption data for the City of Niš, which have about 260000 habitans and average daily demand of 182 MW, is used for testing. Double sesonal ARIMA and Holt-Winters as representatives of clasical models and artificial neural networks, least squares support vector machines and relevance vector machines as representatives of artificial models, are used for models evaluation. For a measure of accuracy, mean absolute percentage error, symetrical mean absolute percentage error, square root mean error and absolute percentage error are used. Obtained results show that the best model is model with incremental update scheme, followed by double sesonal ARIMA and artificial neural networks models. The worst results are obtained by relevance vector machines and double sesonal Holt-Winters models. It has been shown that the best model could be successfully used with the short-term load forecasting problem

Evaluation of spectral analysis of intraocular pressure measured by dynamic contour tonometry in primary and exoliative glaucoma

CILJ. Ciljevi našeg istraživanja bili su utvrđivanje spektralnog sadržaja impulsnog talasa intraokularnog pritiska kod bolesnika obolelih od različitih oblika glaukoma u odnosu na zdrave osobe, kao i utvrđivanje eventualnih razlika u spektralnom sadržaju impulsnog talasa intraokularnog pritiska između grupa ispitanika obolelih od različitih tipova glaukoma (primarnog glaukoma otvorenog ugla glaukoma, primarnog glaukoma zatvorenog ugla, normotenzivnog glakoma i kapsularnog glaukoma) u odnosu na kontrolnu grupu (zdravih u pogledu neobolelosti od glaukoma) i međusobno. PACIJENTI I METODE. Studija dizajnirana po tipu studije slučajeva i kontrola obuhvatila je 20 zdravih osoba, 20 novootkrivenih, prethodno nelečenih osoba obolelih od primarnog glaukoma otvorenog ugla, 10 obolelih od primarnog glaukoma zatvorenog ugla, 10 obolelih od kapsularnog glaukoma, 20 obolelih od normotenzivnog glaukoma. Kontinuirani zapis intraokularnog pritiska dobijen dinamičnom konturnom tonometrijom podvrgnut je brzoj Furijeovoj transformaciji i dodatnom statističkom analiziranju. REZULTATI. Spektralne komponente talasa intraokularnog pritiska odredjene su do petog harmonika. Statistički značajne razlike, testirane analizom varijanse, za vrednosti amplitude prvog harmonika pokazane su između kontrolne grupe i grupe primarnog glaukoma otvorenog ugla (p<0.1), između grupe primarnog glaukoma otvorenog ugla i kapsularnog glaukoma (p<0.1), kao i između grupe primarnog glaukoma zatvorenog ugla i kapsularnog glaukoma (p<0.5). Ubedljivo viši prvi harmonici registrovani u grupi primarnog glaukoma otvorenog ugla. Osobe obolele od glaukoma imale su značajno više vrednosti okularne pulsne ampitude. ZAKLJUČAK. Spektralnom analizom zapisa dobijenog dinamičnom konturnom tonometrijom moguće je odrediti spektralne komponente pulsnog talasa intraokularnog pritiska do petog harmonika. Statistički značajno više bile su amplitude prvog harmonika u grupi osoba obolelih od primarnog glaukoma otvorenog ugla. Zidovi krvni sudovi osoba obolelih od glaukoma sa visokim vrednostima intraokularnog pritiska lako osciliraju, iako se nalaze pod dejstvom povišenog pritiska unutar zatvorenog sistema kao što je očna jabučica, odnosno njihov rigiditet je nizak.PURPOSE. To investigate the spectral content of intraocular pressure pulse wave by advanced spectral signal processing of continuous intraocular pressure readings obtained by dynamic contour tonometry. PATIENTS AND METHODS. A non-interventional case control study included 20 healthy subjects, 20 previously untreated primary open angle glaucoma patients, 10 previously untreated primary close angle glaucoma patients, 10 previously untreated exfoliative glaucoma patients and 20 previously untreated low tension glaucoma patients. The continuous intraocular pressure reading obtained by dynamic contour tonometry was submitted to Fast Fourier Transform signal analysis and further statistical data processing. RESULTS. The spectral components of the intraocular pressure pulse wave were discerned up to the fifth harmonic. Highly statistically significant difference was found in the first harmonic amplitude between the control group and the primary open angle glaucoma group (p<0.1), between the primary open angle glaucoma group and the exfoliative glaucoma group (p<0.1) and between the primary close angle glaucoma group and exfoliative glaucoma group (p<0.5). Glaucoma patients had significantly higher ocular pulse volume values. CONCLUSIONS. It is possible to determine spectral components of the intraocular pressure pulse wave up to the fifth harmonic by a spectral analysis of dynamic contour tonometry continuous readings. We found that high ocular pulse amplitude values in primary open angle glaucoma group was associated with high harmonics amplitude, which indicates low rigidity of blood vessels

Performance evaluation and indicators of the efficiency of drainage systems for management of the groundwater regime on agricultural land.

Rizik od prevlaživanja poljoprivrednog zemljišta podzemnim vodama je u manjoj ili većoj meri zastupljen na svim poljoprivrednim površinama. Poznavanje režima podzemnih voda, u različitim prirodnim uslovima, predstavlja osnov za izbor i primenu tehnički ispravnih i ekonomski opravdanih rešenja u oblasti upravljanja režimom podzemnih voda. Upravljanje režimom podzemnih voda na poljoprivrednim područjima je značajno i predstavlja veoma složen i kreativan posao koji iziskuje relevantne i pouzdane informacije o prirodnoj sredini i objektima drenažnih sistema. Takođe, drenažni sistemi najčešće pokrivaju veoma velike površine i sa socio-ekonomskog stanovišta predstavljaju jedne od najvrednijih infrastrukturnih sistema. I pored toga ne postoji jasna metodologija sa kojom bi se mogli kvantifikovati efekti njihovog rada...The risk of waterlogging in agricultural land, due to high groundwater levels, exists to a degree in all agricultural areas. Understanding the groundwater regime in different natural conditions forms the basis for selecting and implementing technically correct and economically viable solutions in a field of groundwater management. Groundwater management in agricultural areas is important and represents very complex and creative work that requires relevant and reliable data on the natural environment and structures of the drainage systems. Also, drainage systems mostly cover wide areas and represent one of the most valuable infrastructural systems, from a socio-economic point of view. In spite of this, there is no clear methodology for quantifying the effects of their work..

Characterization of dispersion strengthened copper with 3wt%Al2O3 by mechanical alloying

The copper matrix has been dispersion strengthened with 3wt. %Al2O3 by mechanical alloying. Commercial alumina powder with an average particle size of 0.751 mum was used for alloying. The mechanical alloying process was performed in a planetary ball mill up to 20h in air. After milling all powders were treated in H-2 at 400(degrees)C for 1h, and finally hot pressing was used for compaction (800degreesC, 3h, Ar). Structure observations revealed a lamellar structure (Al2O3 particles largely restricted to interlamellar planes between adjacent copper lamellae) accompanied also by structure refinement. These structural changes were mostly completed in the early stage of milling, and retained after compaction. Micro. hardness was found to progressively increase with milling time. So, after 5h of milling the micro hardness of the Cu+3twt%Al2O3 compact was 1540MPa, i.e. 2.5 times greater than for the as-received electrolytic copper powder (638MPa) compacted under identical conditions, while after 20h of milling it was 2370 MPa. However, after exposing the tested compact at 800degreesC up to 5h, the achieved hardening effect vanished

Uticaj transgenaze na kvalitet i prinos mesa kunića

In this paper results of the effect of transgenesis on quality and yield of rabbit meat are presented. During the trial body mass of transgenic progeny of F1 generation was monitored and compared to control group (nontransgenic animals of same age). Subsequent to slaughtering, meat yield, ratio between certain musculature parts and meat quality (proteins, lipids, water) were analyzed. Obtained data was compared to control group of animals of same age but standard genotype. Meat colour was evaluated on apparatus Specol 11 and expressed as percentage of remission on wave length of 540 μm. Content of elements in thigh muscle was established subsequent to dry mineralization in spectro-photometer UNICAM 939 Cambridge UK. Phosphorus content was measured spectro-photometrically on apparatus SPECOL 11. Subsequent to measuring and systematization, data was statistically analyzed and processed. Arithmetic mean values for certain groups of data were calculated, and their values compared using t-test (Hadživuković, 1991). Changes established in regard to content of water, lipids, energy and water binding capacity, were relative to changes in histological structure and level of metabolic processes. It is possible that these changes are result of pleiotropic effect of integrated gene. However, in order to confirm and interpret these changes, it is necessary to carry out further researches of the microscopic structure and metabolic processes of muscle tissues in transgenic rabbits.U radu su prikazani rezultati uticaja transgeneze na kvalitet i prinos mesa kunića. Ogled je vršen na komercijalnim tovnim hibridima nastalim ukrštanjem Novozelandskih belih i Kalifornijskih kunića. Dobijeni podaci upoređeni su sa kontrolnom grupom vršnjaka standardnog genotipa. Posmatrani su sledeći parametri kod obe grupe životinja: telesna masa (1, 2, 5, 10, 20 i 30- tog dana starosti), klanični podaci (w-težina pre žrtvovanja, dw- težina nakon iskrvarenja, s-težina kože, sp-težina distalnih delova zadnjih nogu, b- težina polutke sa kožom, hd-težina glave bez kože, fl- težina prednjih nogu, t- težina butova, r-težina rebara (grudi), bk - težina leđa, ht- težina srca, ky-težina bubrega, l- težina pluća, lvtežina jetre, git- težina stomaka i creva sa sadržajem, gite-težina praznog stomaka i creva, f- težina masnoće, bt- težina kostiju nogu, mt-težina mišića nogu, bf- težina kostiju prednjih nogu, c- prinos mesa (obraslost muskulaturom %); kvalitet mesa butova (cw- sadržaj vode, cp - sadržaj proteina, cf- sadržaj masti, ce- energija, pH, cc- boja, bw- kapacitet zadržavanja vode) i sadržaj mikroelemenata u mesu buta (Cu, Zn, Fe, K, Na, Mg, P, Ca). Posle merenja i sistematizacije podaci su statistički obrađeni. Izvršena su izračunavanja aritmetičkih sredina pojedinih grupa podataka, a zatim poređenje njihovih vrednosti t-testom (Hadživuković, 1991). Nizak nivo varijabiliteta u svim starosnim kategorijama u obe posmatrane grupe je jasno vidljiv iz vrednosti standardne greške aritmetičke sredine. To je manifestovano statistički značajnim uticajem procesa transgeneze na živu masu pri rođenju uprkos činjenici da je apsolutna razlika aritmetičkih sredina transgene i kontrolne grupe samo 0,005 kg (0,063±0,001 nasuprot 0,058±0,002) (tabela 1). Ovaj uticaj je na granici P=0,05 u tabeli analize varijanse (tabela 2). Razlika aritmetičkih sredina nije statistički značajna kod ostalih starosnih kategorija i ona se gubi već nakon 48 časova. Može se konstatovati da integrisani gen nema uticaja na porast transgenih kunića. Statistički značaj uticaja integrisanog gena je utvrđen kod parametara koji se odnose na masu distalnih delova transgenih i netransgenih kunića (0,062±0,001 nasuprot 0,069±0,001 kg), težine glave (0,119±0,003 nasuprot 0,128±0,003 kg) i težine butova (0,405±0,010 nasuprot 0,433±0,009 kg). Kod ostalih klaničnih karakteristika koje su testirane nisu utvrđene statistički značajne razlike koje bi bile uslovljene integracijom gena (tabele 3 i 4). Na uzorcima mesa nogu (butovi) praćene su vrednosti koje se odnose na kvalitet mesa (tabele 5 i 6). Dobijeni podaci koji se odnose na sastav mesa (tabela 5) ukazuju da je uticaj integracije gena bio statistički značajan (p (lt) 0,05) u grupi transgenih kunića u poređenju sa netransgenim u pogledu sledećih karakteristika: sadržaj proteina (74,03±0,26 nasuprot 74,84±0,28%), sadržaj masnoće (3,66±0,40 nasuprot 2,32±0,44%), sadržaja energije (495,43±11,81 nasuprot 458,07±12,94%), kapacitet zadržavanja vode (31,66±0,84 nasuprot 35,63±0,92%). Statistički značajne razlike kao posledica uticaja integrisanog gena nisu utvrđene kod ostalih posmatranih parametara (tabela 6). Srednje vrednosti sadržaja elemenata u tkivu mišića pokazale su najveće varijacije od svih posmatranih parametara. Najizraženije varijacije bile su u grupi netransgenih kunića (tabela 7). Broj životinja ili ponavljanja je igrao veliku ulogu. Za većinu posmatranih karakteristika može se reći da nisu pokazale uticaj integrisanog WAP- hFVIII gena u genotipu kunića. Značajnije razlike pojavile su se samo u okviru nekih parametara kvaliteta mesa (tabela 8). Rezultati ukazuju da nije utvrđeno ni prisustvo rhFVIII u skeletnim mišićima transgenih kunića

Vitamin a and the nervous system

Vitamin A is essential for the early development and normal functioning of the brain throughout life. A deficiency of vitamin A is one of the leading causes of morbidity and mortality in developing countries, and subclinical deficiency is probably present worldwide. The main active molecule in vitamin A is retinoic acid, which is involved in vision, the immune system, skin health, olfaction and cognition (learning, memory, spatial functions, olfaction, etc.) through processes of neuroplasticity and neurogenesis. Vitamin A is involved in the regulation of about one-sixth of the human genome. It has non-genomic actions in protein translation and paracrine actions. Retinal vitamin A aldehyde is crucial for day and night vision. The best-known manifestation of hypovitaminosis A is night blindness but in more severe cases, it causes blindness. In the hypothalamus, vitamin A, with information from the retina, acts in circadian and seasonal regulation. Increased retinoic acid levels in the blood are associated with increased risk of depression, and lower levels have been connected with Alzheimer's disease, Parkinson's disease, cerebral ischemia, autistic spectrum disorders and schizophrenia. Higher doses and longer periods of treatment pose the threat of hypervitaminosis A. Vitamin A and its analogs are a promising new class of therapeutic agents in a wide spectrum of disorders, albeit with a narrow therapeutic window