1,354 research outputs found
Simple colorimetric method determines uranium in tissue
Simple colorimetric micromethod determines concentrations of uranium in tissue. The method involves dry ashing organic extraction, and colorimetric determination of uranyl ferrocyanide. This uranium determination technique could be used in agricultural research, tracer studies, testing of food products, or medical research
Ceric and ferrous dosimeters show precision for 50-5000 rad range
Ammonium thiocyanate, added to the usual ferrous sulfate dosimeter solution, yielded a very stable, precise and temperature-independent system eight times as sensitive as the classical Fricke system in the 50 to 5000 rad range. The ceric dosimeters, promising for use in mixed radiation fields, respond nearly independently of LET
On the Incompatibility of Standard Quantum Mechanics and the de Broglie-Bohm Theory
It is shown that the de Broglie-Bohm quantum theory of multi-particle systems
is incompatible with the standard quantum theory of such systems unless the
former is ergodic. A realistic experiment is suggested to distinguish between
the two theories.Comment: A few technical changes incorporated in section V without any change
in conclusion
1.55 μm direct bandgap electroluminescence from strained n-Ge quantum wells grown on Si substrates
Electroluminescence from strained n-Ge quantum well light emitting diodes grown on a silicon substrate are demonstrated at room temperature. Electroluminescence characterisation demonstrates two peaks around 1.55 μm and 1.8 μm, which correspond to recombination between the direct and indirect transitions, respectively. The emission wavelength can be tuned by around 4% through changing the current density through the device. The devices have potential applications in the fields of optical interconnects, gas sensing, and healthcare
European development banks and the political cycle
This paper investigates whether the lending activity of European development banks is affected by opportunistic political behavior, by looking at the change in loans extended by these entities in election years. The empirical analysis leverages on a unique manually collected dataset that includes all the development banks headquartered in Europe, for the period 2002\u20132015. A comparison with the rest of the European banking system reveals that while the political view of development banks cannot be supported as a general rule, it finds empirical evidence in flawed democracies, where large development banks actually tend to increase their lending activity in election years
Monojet searches for momentum-dependent dark matter interactions
We consider minimal dark matter scenarios featuring momentum-dependent couplings of the dark sector to the Standard Model. We derive constraints from existing LHC searches in the monojet channel, estimate the future LHC sensitivity for an integrated luminosity of 300 fb−1, and compare with models exhibiting conventional momentum-independent interactions with the dark sector. In addition to being well motivated by (composite) pseudo-Goldstone dark matter scenarios, momentum-dependent couplings are interesting as they weaken direct detection constraints. For a specific dark matter mass, the LHC turns out to be sensitive to smaller signal cross-sections in the momentum-dependent case, by virtue of the harder jet transverse-momentum distribution
Alexander quandle lower bounds for link genera
We denote by Q_F the family of the Alexander quandle structures supported by
finite fields. For every k-component oriented link L, every partition P of L
into h:=|P| sublinks, and every labelling z of such a partition by the natural
numbers z_1,...,z_n, the number of X-colorings of any diagram of (L,z) is a
well-defined invariant of (L,P), of the form q^(a_X(L,P,z)+1) for some natural
number a_X(L,P,z). Letting X and z vary in Q_F and among the labellings of P,
we define a derived invariant A_Q(L,P)=sup a_X(L,P,z).
If P_M is such that |P_M|=k, we show that A_Q(L,P_M) is a lower bound for
t(L), where t(L) is the tunnel number of L. If P is a "boundary partition" of L
and g(L,P) denotes the infimum among the sums of the genera of a system of
disjoint Seifert surfaces for the L_j's, then we show that A_Q(L,P) is at most
2g(L,P)+2k-|P|-1. We set A_Q(L):=A_Q(L,P_m), where |P_m|=1. By elaborating on a
suitable version of a result by Inoue, we show that when L=K is a knot then
A_Q(K) is bounded above by A(K), where A(K) is the breadth of the Alexander
polynomial of K. However, for every g we exhibit examples of genus-g knots
having the same Alexander polynomial but different quandle invariants A_Q.
Moreover, in such examples A_Q provides sharp lower bounds for the genera of
the knots. On the other hand, A_Q(L) can give better lower bounds on the genus
than A(L), when L has at least two components.
We show that in order to compute A_Q(L) it is enough to consider only
colorings with respect to the constant labelling z=1. In the case when L=K is a
knot, if either A_Q(K)=A(K) or A_Q(K) provides a sharp lower bound for the knot
genus, or if A_Q(K)=1, then A_Q(K) can be realized by means of the proper
subfamily of quandles X=(F_p,*), where p varies among the odd prime numbers.Comment: 36 pages; 16 figure
Minimal seesaw mechanism
In the framework of the seesaw mechanism, and adopting a typical form for the
Dirac neutrino mass matrix, we discuss the impact of minimal forms of the
Majorana neutrino mass matrix. These matrices contain four or three texture
zeros and only two parameters, a scale factor and a hierarchy parameter. Some
forms are not compatible with large lepton mixing and are ruled out. Moreover,
a normal mass hierarchy for neutrinos is predicted.Comment: 9 pages, RevTex4. Revise
Modelling of an intersubband quantum confined Stark effect in Ge quantum wells for mid-infrared photonics
: In this work we theoretically investigate quantum confined Stark effect of intersubband transitions in asymmetric Ge/SiGe quantum wells for intensity modulation in the mid-infrared. Our calculations show that extinction ratios up to 1 dB and modulation speeds of several tens of GHz could be obtained in 100 µm long waveguides
Mid-Infrared Plasmonic Platform Based on n-Doped Ge-on-Si: Molecular Sensing with Germanium Nano-Antennas on Si
CMOS-compatible, heavily-doped semiconductor
films are very promising for applications in mid-infrared
plasmonic devices because the real part of their dielectric
function is negative and broadly tunable in this wavelength
range. In this work we investigate n-type doped germanium
epilayers grown on Si substrates. We design and realize Ge nanoantennas
on Si substrates demonstrating the presence of localized
plasmon resonances, and exploit them for molecular sensing in
the mid-infrared
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