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

Trajectory-based interpretation of laser light diffraction by a sharp edge

In the diffraction pattern produced by a half-plane sharp edge when it obstructs the passage of a laser beam, two characteristic regions are noticeable. There is a central region, where it can be noticed the diffraction of laser light in the region of geometric shadow, while intensity oscillations are observed in the non-obstructed area. On both sides of the edge, there are also very long light traces along the normal to the edge of the obstacle. The theoretical explanation to this phenomenon is based on the Fresnel-Kirchhoff diffraction theory applied to the Gaussian beam propagation behind the obstacle. Here we have supplemented this explanation by considering electromagnetic flow lines, which provide a more complete interpretation of the phenomenon in terms of electric and magnetic fields and flux lines, and that can be related, at the same time, with average photon paths.Comment: 13 pages, 5 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

Sites of conscience as guardians of the collective memory

Kada je kraj XX veka doneo etniĉki motivisane sukobe u Evropi, ali i neprijateljstva unutar granica represivnih reţima u drugim delovima sveta, bilo je jasno da nijedan postojeći naĉin pamćenja i didaktiĉkog delovanja u pravcu neponavljanja zloĉina nije ostvario rezultat. Na krilaticu never again senku je bacilo novo, neţeljeno nasleĎe te se opravdano postavilo pitanje - ako to nasleĊe treba ĉuvati, koji bi bio najzahvalniji model za to? Kroz promišljanja o povezivanju sećanja, inaĉe elementa neopipljive baštine, sa fiziĉkim prostorom, te istraţivanja kako taj odnos interpretirati kao muzeološku / heritološku temu iskristalisao se i odgovor na gore postavljenu nedoumicu. Rešenje se pronašlo u mestima buĎenja savesti, jedinstvenim modelima oĉuvanja kolektivne memorije i disonantnog nasleĊa u tranzicionim društvima koja su u bliskoj prošlosti pretrpela masovne zloĉine. Reĉ je o fenomenima koji obuhvataju elemente mnogih ranijih vidova memorijalizacije, a svoju misiju postiţu ispitivanjem odnosa izmeĊu kulturnog identiteta, svakodnevnog ţivota, politike, pamćenja i prostora. Uz nezaobilaznu emotivnu i pedagošku funkciju, mesta buĎenja savesti treba da budu svedoci kako su se pojedinci odnosili prema sukobima u prošlosti, meĊusobna veza sa ljudima u nekim drugaĉijim okolnostima, ali i prostor od poverenja za savladavanje novih stanovišta. Najveći izazov u postizanju tih ciljeva svakako je prilagoĊavanje komemorativne umetnosti potrebama lokalnog stanovništva, specifiĉnom kontekstu i kulturi. Iz perspektive tranzicione pravde, gde se ovaj termin prvi put pominje, mesta buĎenja savesti su deo procesa memorijalizacije u domenu simboliĉkih reparacija. Memorijalizacija je proces kreiranja javnih memorijala, a javni memorijali obuhvataju razliĉite projekte i aktivnosti koji se dešavaju u javnoj sferi, u ţelji da zaštite sećanje na dogaĊaje, periode i liĉnosti od znaĉaja za ţivot odreĊene individue, porodice, društvene grupe ili zajednicu u celini...When the end of the 20th century brought ethnically motivated conflicts in Europe, as well as hostilities within the borders of repressive regimes in other parts of the world, it was clear that no existing form of remembrance and didactics aimed at preventing the recurrence of crimes had succeeded. A new, dissonant heritage cast a shadow over the slogan never again, and thus a valid question has been raised - if this legacy is to be protected, what would be the most appropriate model for that? The answer to the aforementioned dilemma has taken shape through reflection on ways to connect memory, as an element of intangible heritage, to physical space, and through research on ways to interpret this relationship as a subject of museology/ heritology. The solution has been found in sites of conscience, a unique model of preserving the collective memory and dissonant heritage in the societies in transition that have suffered mass atrocities in the recent past. We refer to the phenomena that include elements of many earlier forms of memorialization, fulfilling their mission by examining the links between cultural identity, daily life, politics, memory and space. With the inevitable emotional and pedagogical functions, sites of conscience should present how individuals related to the past conflicts, they should connect people who now find themselves in different circumstances, but also be areas of confidence building to gain new perspectives. The biggest challenge in achieving these goals is certainly the adjustment of commemorative art to the needs of the local population, the specific context and culture..

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

Fertilitet krmača posle intracervikalnog ili intrauterinog osemenjavanja različitim brojem spermatozoida u dozama redukovanog volumena

Modern intensive pig production demands an increasing number of insemination doses per ejaculate of genetically superior boars. In order to achieve such a result the possibility of producing insemination doses in both reduced volume and spermatozoa count without decreasing the fertility of sows is studied. In this trial we studied the effect of insemination with reduced volumes of semen (50 mL) and varied spermatozoa count (4, 2 or 1x109). Insemination was performed by the classical (intracervical) or by the new (intrauterine) techniques and the basic fertility parameters (farrowing % and litter size) were measured. The farrowing value decreased with decreasing spermatozoa numbers after intracervical and intrauterine insemination. However, the farrowing value, regardless of spermatozoa numbers, was significantly higher after intrauterine insemination (83.3%, 76.7%, 66.7%) compared to the classical intracervical insemination (73.3%, 66.7% and 50%). Litters size did not vary significantly depending on the applied insemination procedure or spermatozoa number. These results indicate that application of the new intrauterine insemination procedure enables the use of doses with a smaller volume and spermatozoa number, at the same time obtaining a satisfactory farrowing and litter size. This opens the possibility of obtaining a significantly higher number of doses per ejaculate when compared to the classical intracervical insemination procedure. In such a way can be increased significantly the degree of reproductive exploitation of genetically superior boars.Savremena intenzivna proizvodnja svinja zahteva dobijanje što većeg broja inseminacionih doza po ejakulatu genetski superiornih nerastova. Radi realizacije ovog cilja, istražuju se mogućnosti pravljenja inseminacionih doza redukovanog volumena i broja spermatozoida, ali da inseminacija ovakvim dozama ne rezultuje smanjenim fertilitetom krmača. U ovom radu je ispitivan uticaj osemenjavanja dozama duplo redukovanog volumena (50 ml) i različitog broja spermatozoida u dozi (4, 2 ili 1x109), posle klasične (intracervikalne) i nove (intrauterine) tehnologije osemenjavanja, na osnovne parametre fertiliteta krmača (% prašenja i veličina legla). Vrednost prašenja je opadala sa smanjenjem broja spermatozoida u dozi, kako posle intracervikalnog, tako i posle intratuterinog osemenjavanja. Međutim, vrednost prašenja je, bez obzira na broj spermatozoida u dozi, bila znatno veća posle intrauterinog (83,3%, 76,7% i 66,7%) u odnosu na klasično intracervikalno osemenjavanje (73,3%, 66,7% i 50%). Veličina legla nije značajno varirala u zavisnosti od primenjene metode osemenjavanja ili broja spermatozoida u dozi. Ovi rezultati ukazuju da je, primenom nove tehnologije intrauterinog osemenjavanja, moguće koristiti doze znatno redukovanog volumena i broja spermatozoida, a da se, pri tome, postignu zadovoljavajuće vrednosti prašenja i veličine legla. Ovo stvara mogućnost dobijanja značajno većeg broja doza po ejakulatu, u odnosu na klasičnu tehnologiju intracervikalnog osemenjavanja. Time se može značajno povećati stepen reproduktivne eksploatacije genetski superiornih nerastova

On the influence of resonance photon scattering on atom interference

Here, the influence of resonance photon-atom scattering on the atom interference pattern at the exit of a three-grating Mach-Zehnder interferometer is studied. It is assumed that the scattering process does not destroy the atomic wave function describing the state of the atom before the scattering process takes place, but only induces a certain shift and change of its phase. We find that the visibility of the interference strongly depends on the statistical distribution of transferred momenta to the atom during the photon-atom scattering event. This also explains the experimentally observed (Chapman et al 1995 Phys. Rev. Lett. 75 2783) dependence of the visibility on the ratio d_p/\lambda_i = y'_{12} (2\pi/kd\lambda_i), where y'_{12} is distance between the place where the scattering event occurs and the first grating, k is the wave number of the atomic center-of-mass motion, $d$ is the grating constant and \lambda_i is the photon wavelength. Furthermore, it is remarkable that photon-atom scattering events happen experimentally within the Fresnel region, i.e. the near field region, associated with the first grating, which should be taken into account when drawing conclusions about the relevance of "which-way" information for the interference visibility.Comment: 9 pages, 1 figur

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cyg

Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornestones to critical tests of stellar evolution theory for massive stars. Yet, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyze all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cyg for its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analyzed earlier obtained blue electronic spectra. Our analyses provide the most accurate so far published value of the apsidal period of 47.805 +/- 0.030 yrs and the following physical elements: M1=17.72+/-0.35$ Msun, M2=17.73+/-0.30 Msun, R1=5.785+/-0.091 Rsun, and R2=5.816+/-0.063 Rsun. The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k2 = -1.937. A comparison with Claret's stellar interior models implies an age close to 2 millions yrs for both stars. The claimed accuracy of modern element determination of 1-2 per cent seems still a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable.Comment: 13 pages; accepted for publication in Astronomy and Astrophysic