561 research outputs found
Large K-exciton dynamics in GaN epilayers: the non-thermal and thermal regime
We present a detailed investigation concerning the exciton dynamics in GaN
epilayers grown on c-plane sapphire substrates, focussing on the exciton
formation and the transition from the nonthermal to the thermal regime. The
time-resolved kinetics of LO-phonon replicas is used to address the energy
relaxation in the excitonic band. From ps time-resolved spectra we bring
evidence for a long lasting non-thermal excitonic distribution which accounts
for the rst 50 ps. Such a behavior is con rmed in di erent experimental
conditions, both when non-resonant and resonant excitation are used. At low
excitation power density the exciton formation and their subsequent
thermalization is dominated by impurity scattering rather than by acoustic
phonon scattering. The estimate of the average energy of the excitons as a
function of delay after the excitation pulse provides information on the
relaxation time, which describes the evolution of the exciton population to the
thermal regime.Comment: 9 pages,8 figure
Finite-size effects on the dynamic susceptibility of CoPhOMe single-chain molecular magnets in presence of a static magnetic field
The static and dynamic properties of the single-chain molecular magnet
[Co(hfac)NITPhOMe] are investigated in the framework of the Ising model
with Glauber dynamics, in order to take into account both the effect of an
applied magnetic field and a finite size of the chains. For static fields of
moderate intensity and short chain lengths, the approximation of a
mono-exponential decay of the magnetization fluctuations is found to be valid
at low temperatures; for strong fields and long chains, a multi-exponential
decay should rather be assumed. The effect of an oscillating magnetic field,
with intensity much smaller than that of the static one, is included in the
theory in order to obtain the dynamic susceptibility . We find
that, for an open chain with spins, can be written as a
weighted sum of frequency contributions, with a sum rule relating the
frequency weights to the static susceptibility of the chain. Very good
agreement is found between the theoretical dynamic susceptibility and the ac
susceptibility measured in moderate static fields ( kOe),
where the approximation of a single dominating frequency turns out to be valid.
For static fields in this range, new data for the relaxation time,
versus , of the magnetization of CoPhOMe at low temperature are
also well reproduced by theory, provided that finite-size effects are included.Comment: 16 pages, 9 figure
Smart automotive technology adherence to the law: (de)constructing road rules for autonomous system development, verification and safety
Driving is an intuitive task that requires skill, constant alertness and vigilance for unexpected events. The driving task also requires long concentration spans, focusing on the entire task for prolonged periods, and sophisticated negotiation skills with other road users including wild animals. Modern motor vehicles include an array of smart assistive and autonomous driving systems capable of subsuming some, most, or in limited cases, all of the driving task. Building these smart automotive systems requires software developers with highly technical software engineering skills, and now a lawyer’s in-depth knowledge of traffic legislation as well. This article presents an approach for deconstructing the complicated legalese of traffic law and representing its requirements and flow. Our approach (de)constructs road rules in legal terminology and specifies them in ‘structured English logic’ that is expressed as ‘Boolean logic’ for automation and ‘Lawmaps’ for visualization. We demonstrate an example using these tools leading to the construction and validation of a ‘Bayesian Network model’. We strongly believe these tools to be approachable by programmers and the general public, useful in development of Artificial Intelligence to underpin motor vehicle smart systems, and in validation to ensure these systems are considerate of the law when making decisions.fals
Medicinal Plants and Their Bacterial Microbiota: A Review on Antimicrobial Compounds Production for Plant and Human Health
Medicinal plants (MPs) have been used since antiquity in traditional and popular medicine, and they represent a very important source of bioactive molecules, including antibiotic, antiviral, and antifungal molecules. Such compounds are often of plant origin, but in some cases, an origin or a modification from plant microbiota has been shown. Actually, the research continues to report the production of bioactive molecules by plants, but the role of plant–endophytic interaction is emerging. Classic examples are mainly concerned with fungal endophytes; however, it has been recently shown that bacterial endophytes can also play an important role in influencing the plant metabolism related to the synthesis of bioactive compounds. In spite of this, a deep investigation on the power of MP bacterial endophytes is lacking. Here, an overview of the studies on MP bacterial microbiota and its role in the production of plant antimicrobial compounds contributing to prime host defense system and representing a huge resource for biotech and therapeutic applications is provided
Eradication of isolated para-aortic nodal recurrence in a patient with an advanced high grade sorous ovarian carcinoma: our experience and review of literature
Abstract: We report a case report regarding the eradication of isolated lymph-nodal para-aortic recurrence
in the aortic region down the left renal vein (LRV) in a patient treated two years earlier in
another hospital for a FIGO stage IC2 high-grade serous ovarian carcinoma with a video showing
the para-aortic space after eradication of the metastatic tissue. A 66 year-old woman was admitted
24 months after the initial surgical procedure for an increased Ca 125 level and CT scan that revealed
a 3 cm para-aortic infrarenal lymph-nodal recurrence that was confirmed by PET/CT scan. A secondary
cytoreductive surgery (SCS) with a para-aortic lymph-nodal dissection of the tissue down
the LRV and radical omentectomy were performed: during the cytoreduction, the right hemicolon
was mobilized. The anterior surface of the inferior vena cava (IVC), aorta and LRV were exposed.
The metastatic lymph nodes were detected in the para-ortic space down the proximal part of the
LRV and eradicated; an en bloc infrarenal lymph-node dissection from the aortocaval region was
performed. The operative time during the surgical procedure was 212 min with a blood loss of 120
mL. No intra- and postoperative complications, including ureteral or vascular injury or renal dysfunction,
occurred. At histological examination, three dissected lymph nodes were positive for metastasis,
and the patient was discharged five days after laparotomy without side effects and underwent
chemotherapy 3 weeks later; after a follow-up of 42 months, no recurrence was detected. In
conclusion, secondary debulking surgery can be considered a safe and effective therapeutic option
for the management of recurrences, although long-term follow-ups are necessary to evaluate the
overall oncologic outcomes of this procedure
The JAK2V617 mutation induces constitutive activation and agonist hypersensitivity in basophils of polycythemia vera.
BACKGROUND: The JAK2V617F mutation has been associated with constitutive and enhanced activation of neutrophils, while no information is available concerning other leukocyte subtypes. DESIGN AND METHODS: We evaluated correlations between JAK2V617F mutation and the count of circulating basophils, the number of activated CD63(+) basophils, their response in vitro to agonists as well as the effects of a JAK2 inhibitor. RESULTS: We found that basophil count was increased in patients with JAK2V617F -positive myeloproliferative neoplasms, particularly in those with polycythemia vera, and was correlated with the V617F burden. The burden of V617F allele was similar in neutrophils and basophils from patients with polycythemia vera, while total JAK2 mRNA content was remarkably greater in the basophils; however, the content of JAK2 protein in basophils was not increased. The number of CD63(+) basophils was higher in patients with polycythemia vera than in healthy subjects or patients with essential thrombocythemia or primary myelofibrosis and was correlated with the V617F burden. Ultrastructurally, basophils from patients with polycythemia vera contained an increased number of granules, most of which were empty suggesting cell degranulation in vivo. Ex vivo experiments revealed that basophils from patients with polycythemia vera were hypersensitive to the priming effect of interleukin-3 and to f-MLP-induced activation; pre-treatment with a JAK2 inhibitor reduced polycythemia vera basophil activation. Finally, we found that the number of circulating CD63(+) basophils was significantly greater in patients suffering from aquagenic pruritus, who also showed a higher V617F allele burden. CONCLUSIONS: These data indicate that the number of constitutively activated and hypersensitive circulating basophils is increased in polycythemia vera, underscoring a role of JAK2V617F in these cells’ abnormal function and, putatively, in the pathogenesis of pruritus
Spin canting in a Dy-based Single-Chain Magnet with dominant next-nearest neighbor antiferromagnetic interactions
We investigate theoretically and experimentally the static magnetic
properties of single crystals of the molecular-based Single-Chain Magnet (SCM)
of formula [Dy(hfac)NIT(CHOPh)] comprising
alternating Dy and organic radicals. A peculiar inversion between maxima
and minima in the angular dependence of the magnetic molar susceptibility
occurs on increasing temperature. Using information regarding the
monomeric building block as well as an {\it ab initio} estimation of the
magnetic anisotropy of the Dy ion, this anisotropy-inversion phenomenon
can be assigned to weak one-dimensional ferromagnetism along the chain axis.
This indicates that antiferromagnetic next-nearest-neighbor interactions
between Dy ions dominate, despite the large Dy-Dy separation, over the
nearest-neighbor interactions between the radicals and the Dy ions.
Measurements of the field dependence of the magnetization, both along and
perpendicularly to the chain, and of the angular dependence of in a
strong magnetic field confirm such an interpretation. Transfer matrix
simulations of the experimental measurements are performed using a classical
one-dimensional spin model with antiferromagnetic Heisenberg exchange
interaction and non-collinear uniaxial single-ion anisotropies favoring a
canted antiferromagnetic spin arrangement, with a net magnetic moment along the
chain axis. The fine agreement obtained with experimental data provides
estimates of the Hamiltonian parameters, essential for further study of the
dynamics of rare-earths based molecular chains.Comment: 11 pages, 8 figure
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