274 research outputs found
Two-stage Kondo effect in a four-electron artificial atom
An artificial atom with four electrons is driven through a singlet-triplet
transition by varying the confining potential. In the triplet, a Kondo peak
with a narrow dip at drain-source voltage V_ds=0 is observed. The low energy
scale V_ds* characterizing the dip is consistent with predictions for the
two-stage Kondo effect. The phenomenon is studied as a function of temperature
T and magnetic field B, parallel to the two-dimensional electron gas. The low
energy scales T* and B* are extracted from the behavior of the zero-bias
conductance and are compared to the low energy scale V_ds* obtained from the
differential conductance. Good agreement is found between kT* and |g|muB*, but
eV_ds* is larger, perhaps because of nonequilibrium effects.Comment: 7 pages, 7 figures. Added labels on Fig. 3f and one referenc
Spin-Dependent Tunneling of Single Electrons into an Empty Quantum Dot
Using real-time charge sensing and gate pulsing techniques we measure the
ratio of the rates for tunneling into the excited and ground spin states of a
single-electron AlGaAs/GaAs quantum dot in a parallel magnetic field. We find
that the ratio decreases with increasing magnetic field until tunneling into
the excited spin state is completely suppressed. However, we find that by
adjusting the voltages on the surface gates to change the orbital configuration
of the dot we can restore tunneling into the excited spin state and that the
ratio reaches a maximum when the dot is symmetric.Comment: 4 pages, 3 figure
Electrical control of spin relaxation in a quantum dot
We demonstrate electrical control of the spin relaxation time T_1 between
Zeeman split spin states of a single electron in a lateral quantum dot. We find
that relaxation is mediated by the spin-orbit interaction, and by manipulating
the orbital states of the dot using gate voltages we vary the relaxation rate
W= (T_1)^-1 by over an order of magnitude. The dependence of W on orbital
confinement agrees with theoretical predictions and from these data we extract
the spin-orbit length. We also measure the dependence of W on magnetic field
and demonstrate that spin-orbit mediated coupling to phonons is the dominant
relaxation mechanism down to 1T, where T_1 exceeds 1s.Comment: 4 pages, 3 figure
The role of strategic planning in relationship marketing
The evolution of relationship marketing has been one of the most talked about, partly because it not only proposed a radical change at the very beginning of the marketing action and philosophy, but also because of its complexity.Among many different issues regarding the relationship marketing, the one referring to the strategic planning process has been very little dealt with among the marketing specialists.The present article discusses this sensitive matter and represents a short insight into this complex dilemma: is planning possible or not when talking about commitment, trust, harmony, empathy with the consumer on a regular basis, during a lifetime relationship?
Host carbon sources modulate cell wall architecture, drug resistance and virulence in a fungal pathogen
The survival of all microbes depends upon their ability to respond to environmental challenges. To establish infection, pathogens such as Candida albicans must mount effective stress responses to counter host defences while adapting to dynamic changes in nutrient status within host niches. Studies of C. albicans stress adaptation have generally been performed on glucose-grown cells, leaving the effects of alternative carbon sources upon stress resistance largely unexplored. We have shown that growth on alternative carbon sources, such as lactate, strongly influence the resistance of C. albicans to antifungal drugs, osmotic and cell wall stresses. Similar trends were observed in clinical isolates and other pathogenic Candida species. The increased stress resistance of C. albicans was not dependent on key stress (Hog1) and cell integrity (Mkc1) signalling pathways. Instead, increased stress resistance was promoted by major changes in the architecture and biophysical properties of the cell wall. Glucose- and lactate-grown cells displayed significant differences in cell wall mass, ultrastructure, elasticity and adhesion. Changes in carbon source also altered the virulence of C. albicans in models of systemic candidiasis and vaginitis, confirming the importance of alternative carbon sources within host niches during C. albicans infection
Energy Dependent Tunneling in a Quantum Dot
We present measurements of the rates for an electron to tunnel on and off a
quantum dot, obtained using a quantum point contact charge sensor. The tunnel
rates show exponential dependence on drain-source bias and plunger gate
voltages. The tunneling process is shown to be elastic, and a model describing
tunneling in terms of the dot energy relative to the height of the tunnel
barrier quantitatively describes the measurements.Comment: 4 pages, 4 figure
Global analysis of mutations driving microevolution of a heterozygous diploid fungal pathogen
Data deposition: The sequence reported in this paper has been deposited in the NCBI Sequence Read Archive, https://www.ncbi.nlm.nih.gov/bioproject (BioProject ID PRJNA345600). This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1806002115/-/DCSupplemental.Peer reviewedPublisher PD
- …