Consequences of Spin-Orbit Coupling at the Single Hole Level: Spin-Flip Tunneling and the Anisotropic g Factor.

Hole transport experiments were performed on a gated double quantum dot device defined in a p-GaAs/AlGaAs heterostructure with a single hole occupancy in each dot. The charging diagram of the device was mapped out using charge detection confirming that the single hole limit is reached. In that limit, a detailed study of the two-hole spin system was performed using high bias magnetotransport spectroscopy. In contrast to electron systems, the hole spin was found not to be conserved during interdot resonant tunneling. This allows one to fully map out the two-hole energy spectrum as a function of the magnitude and the direction of the external magnetic field. The heavy-hole g factor was extracted and shown to be strongly anisotropic, with a value of 1.45 for a perpendicular field and close to zero for an in-plane field as required for hybridizing schemes between spin and photonic quantum platforms.

Long-range spin transfer in triple quantum dots.

Tunneling in a quantum coherent structure is not restricted to only nearest neighbors. Hopping between distant sites is possible via the virtual occupation of otherwise avoided intermediate states. Here we report the observation of long-range transitions in the transport through three quantum dots coupled in series. A single electron is delocalized between the left and right quantum dots, while the center one remains always empty. Superpositions are formed, and both charge and spin are exchanged between the outermost dots. The delocalized electron acts as a quantum bus transferring the spin state from one end to the other. Spin selection is enabled by spin correlations. The process is detected via the observation of narrow resonances which are insensitive to Pauli spin blockade.

Quantum interference between three two-spin states in a double quantum dot.

Qubits based on the singlet (S) and the triplet (T(0), T(+)) states in double quantum dots have been demonstrated in separate experiments. It has been recently proposed theoretically that under certain conditions a quantum interference could occur from the interplay between these two qubit species. Here we report experiments and modeling that confirm these theoretical predictions and identify the conditions under which this interference occurs. Density matrix calculations show that the interference pattern manifests primarily via the occupation of the common singlet state. The S/T(0) qubit is found to have a much longer coherence time as compared to the S/T(+) qubit.

The Management of Patients after Surgical Treatment of Maxillofacial Tumors.

Morphological and functional disturbances induced by postsurgical defects and loss of tissues in the stomatognathic system due to the treatment of tumors in the maxillofacial region determine the therapeutic needs of patients. The study aimed at clinical and epidemiological evaluation of patients under prosthetic treatment in order to establish the algorithm for rehabilitation. The study group was composed of the patients after midface surgery (45.74%); surgery in a lower part of the face (47.38%); mixed postoperative losses (3.44%); loss of face tissues and surgery in other locations in the head and neck region (3.44%). The supplementary treatment was applied in 69.63% of patients. Clinical and additional examinations were performed to obtain the picture of postoperative loss, its magnitude, and location to plan the strategy of prosthetic rehabilitation. The management algorithm for prosthetic rehabilitation in patients after surgical treatment of maxillofacial neoplasms was based on its division in stages. The location and magnitude of postoperative losses, as well as the implementation of supplementary treatment of the patients after treatment of maxillofacial tumors, influence the planning of prosthetic rehabilitation that plays a key role and facilitates the patients' return to their prior living situation, occupational and family lives.

The size and continuity of DNA segments integrated in Bacillus transformation.

We investigated the size and continuity of DNA segments integrated in Bacillus subtilis transformation. We transformed B. subtilis strain 1A2 toward rifampicin resistance (coded by rpoB) with genomic DNA and with a PCR-amplified 3.4-kb segment of the rpoB gene from several donors. Restriction analysis showed that smaller lengths of donor DNA integrated into the chromosome with transformation by PCR-amplified DNA than by genomic DNA. Nevertheless, integration of very short segments (< 2 kb) from large, genomic donor molecules was not a rare event. With PCR-amplified segments as donor DNA, smaller fragments were integrated when there was greater sequence divergence between donor and recipient. There was a large stochastic component to the pattern of recombination. We detected discontinuity in the integration of donor segments within the rpoB gene, probably due to multiple integration events involving a single donor molecule. The transfer of adaptations across Bacillus species may be facilitated by the small sizes of DNA segments integrated in transformation.

The log-linear relationship between sexual isolation and sequence divergence in Bacillus transformation is robust.

The relationship between sexual isolation and sequence divergence in Bacillus transformation was previously shown to be log linear. In the present study, we have shown that this relationship is robust with respect to naturally occurring genetic variation among recipient strains of Bacillus subtilis and B. mojavensis. Naturally occurring restriction endonuclease activity was shown not to affect this relationship. Also, seven out of eight recombination mutants tested for their sensitivity to sequence divergence have shown the same relationship between sequence divergence and sexual isolation; a mutant for recH was more sensitive to sequence divergence, suggesting that the product of this gene may be involved in resolution of mismatches in heterogamic transformation. We have also shown that the relationship between sexual isolation and sequence divergence is robust with respect to variation in the conditions of transformation, including variation in the length of donor DNA, the concentration of donor DNA, and intracellular competition between donor-derived and recipient-derived DNA. The robustness of the relationship between sexual isolation and sequence divergence among naturally occurring strains and across transformation conditions allows us to predict the eventual outcome of sequence divergence among B. subtilis and its closest relatives.

Direct blotting electrophoresis for sequencing and genotyping hepatitis C virus.

Many methods have been used to differentiate the hepatitis C virus (HCV) genotypes based on, for example, type specific primers, probes and restriction fragment length polymorphism. However, determination of the nucleotide sequence remains the reference. Therefore, a simple non-radioactive cycle sequencing technique was developed for clinical tests. PCR-amplified products of the 5' non-coding region (from position -274 to -31) were sequenced using a 5' digoxygenin-labeled primer. After denaturation, the samples were loaded on a direct blotting electrophoresis system (GATC 1500). Sequencing products were blotted onto a nylon membrane during the electrophoresis. The DNA fragments were then UV-cross-linked, incubated with phosphatase-labeled anti-digoxygenin antibody and stained with a precipitating substrate. Reading the sequence of six samples were possible within 2 days. In 41 different samples, five different genotypes were found by sequence analysis from position -245 to -69, of which 17 were type 1a, 7 type 1b, 5 type 2a, 8 type 3a, 3 type 4 and 1 type 5. These results agreed with those obtained by reverse hybridization assay. Direct blotting electrophoresis offered a good non-radioactive method of performing clinical sequencing on a medium scale, with a minimum of investment.

Oral cavity as a potential source of infections in recipients with diabetes mellitus.

Our previous observations showed alterations of oral cavity status among hemodialyzed patients and kidney allograft recipients as well as differences in the prevalence and composition of microorganisms occurring in the mouths of patients. In the present work, we analysed the results of oral cavity examinations, the identification of microorganisms, and the assessment of their importance to kidney allograft recipients or hemodialyzed patients with diabetes mellitus, in comparison with nondiabetic recipients, dialyzed patients, and control patients.

Bipolar spin blockade and coherent state superpositions in a triple quantum dot.

Spin qubits based on interacting spins in double quantum dots have been demonstrated successfully. Readout of the qubit state involves a conversion of spin to charge information, which is universally achieved by taking advantage of a spin blockade phenomenon resulting from Pauli's exclusion principle. The archetypal spin blockade transport signature in double quantum dots takes the form of a rectified current. At present, more complex spin qubit circuits including triple quantum dots are being developed. Here we show, both experimentally and theoretically, that in a linear triple quantum dot circuit the spin blockade becomes bipolar with current strongly suppressed in both bias directions and also that a new quantum coherent mechanism becomes relevant. In this mechanism, charge is transferred non-intuitively via coherent states from one end of the linear triple dot circuit to the other, without involving the centre site. Our results have implications for future complex nanospintronic circuits.