361 research outputs found
Nova geokemijska metoda za razlikovanje prirodnih voda
Doneseni su rezultati vlastitih kemijskih analiza sadrfaja
klcrida i sulfata nekih voda u nasemu priobalnom pojasu. Izneseni
su argumenti, koji govore za to, da morska voda i kisnica zauzimlju
poseban polofaj medu svim prirodnim vodama. Na temelju toga,
i uz upotrebu bogate grade o kemizmu nasih rudnica, (Miholic)
izradena je vlastita metoda prirodnoga razvrstavanja voda u osnovne
geokemijske tipove, bazirana na funkciji:
log [Cl-] = f (log [S042-])
U toku kruzenja na zemljinoj kori c1- i so42- obiljefavaju
medusobnim omjerima koncentracija sve prirodne vode. To je
iskoristeno u ovom radu i omogucilo je podijeliti sve vode u slije_
dece tipove: kiilnicki, marini, sulfatni i fosilni tip. Sulfatne vode
predstavljaju antipodni tip fosilnim vodama. Vecina ostalih voda
genetski su vezane istodobno na more i kiSnicu.
Upotrebom prilozenih grafikona ponekada mozemo tumaciti
historiju, starost i neke druge kvalitete prirodnih voda. Uoeena je
i istaknuta okolnost, da su sulfati i kloridi posebno znacajne komponentesolnoga sastava svake prirodne vode i opcenitijeg su znacenja od ostalih komponenata mineralizacije voda. Iznesena je
mogucnost daljnje razdiobe navedenih tipova voda uvodenjem
novih varijabli
A Modification of Teorell\u27s Method for Determining of Small Quantities of Ammonia
In Teorell\u27s method ammonia first reacts with sodium hyporbromite. The excess of the reagent is then used to decolorize the dyestuff, naphtyl-red, by means of which the analysis is made. Krogh applied the method to the analysis of ammonia in water and in the air but the author has encountered difficulties when using it
Momentum distribution of a freely expanding Lieb-Liniger gas
We numerically study free expansion of a few Lieb-Liniger bosons, which are
initially in the ground state of an infinitely deep hard-wall trap. Numerical
calculation is carried out by employing a standard Fourier transform, as
follows from the Fermi-Bose transformation for a time-dependent Lieb-Liniger
gas. We study the evolution of the momentum distribution, the real-space
single-particle density, and the occupancies of natural orbitals. Our numerical
calculation allows us to explore the behavior of these observables in the
transient regime of the expansion, where they are non-trivially affected by the
particle interactions. We derive analytically (by using the stationary phase
approximation) the formula which connects the asymptotic shape of the momentum
distribution and the initial state. For sufficiently large times the momentum
distribution coincides (up to a simple scaling transformation) with the shape
of the real-space single-particle density (the expansion is asymptotically
ballistic). Our analytical and numerical results are in good agreement.Comment: small changes; references correcte
Fermi-Bose transformation for the time-dependent Lieb-Liniger gas
Exact solutions of the Schrodinger equation describing a freely expanding
Lieb-Liniger (LL) gas of delta-interacting bosons in one spatial dimension are
constructed. The many-body wave function is obtained by transforming a fully
antisymmetric (fermionic) time-dependent wave function which obeys the
Schrodinger equation for a free gas. This transformation employs a differential
Fermi-Bose mapping operator which depends on the strength of the interaction
and the number of particles.Comment: 4+ pages, 1 figure; added reference
Anderson localization of a Tonks-Girardeau gas in potentials with controlled disorder
We theoretically demonstrate features of Anderson localization in the
Tonks-Girardeau gas confined in one-dimensional (1D) potentials with controlled
disorder. That is, we investigate the evolution of the single particle density
and correlations of a Tonks-Girardeau wave packet in such disordered
potentials. The wave packet is initially trapped, the trap is suddenly turned
off, and after some time the system evolves into a localized steady state due
to Anderson localization. The density tails of the steady state decay
exponentially, while the coherence in these tails increases. The latter
phenomenon corresponds to the same effect found in incoherent optical solitons
Incoherent matter-wave solitons
The dynamics of matter-wave solitons in Bose-Einstein condensates (BEC) is
considerably affected by the presence of a surrounding thermal cloud and by
condensate depletion during its evolution. We analyze these aspects of BEC
soliton dynamics, using time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory.
The condensate is initially prepared within a harmonic trap at finite
temperature, and solitonic behavior is studied by subsequently propagating the
TDHFB equations without confinement. Numerical results demonstrate the collapse
of the BEC via collisional emission of atom pairs into the thermal cloud,
resulting in splitting of the initial density into two solitonic structures
with opposite momentum. Each one of these solitary matter waves is a mixture of
condensed and noncondensed particles, constituting an analog of optical
random-phase solitons.Comment: 4 pages, 2 figures, new TDHFB result
The single-particle density matrix and the momentum distribution of dark "solitons" in a Tonks-Girardeau gas
We study the reduced single-particle density matrix (RSPDM), the momentum
distribution, natural orbitals and their occupancies, of dark "soliton" (DS)
states in a Tonks-Girardeau gas. DS states are specially tailored excited
many-body eigenstates, which have a dark solitonic notch in their
single-particle density. The momentum distribution of DS states has a
characteristic shape with two sharp spikes. We find that the two spikes arise
due to the high degree of correlation observed within the RSPDM between the
mirror points ( and ) with respect to the dark notch at ; the
correlations oscillate rather than decay as the points and are being
separated.Comment: 9 pages, 8 figure
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