57 research outputs found
Work fluctuations in quantum spin chains
We study the work fluctuations of two types of finite quantum spin chains
under the application of a time-dependent magnetic field in the context of the
fluctuation relation and Jarzynski equality. The two types of quantum chains
correspond to the integrable Ising quantum chain and the nonintegrable XX
quantum chain in a longitudinal magnetic field. For several magnetic field
protocols, the quantum Crooks and Jarzynski relations are numerically tested
and fulfilled. As a more interesting situation, we consider the forcing regime
where a periodic magnetic field is applied. In the Ising case we give an exact
solution in terms of double-confluent Heun functions. We show that the
fluctuations of the work performed by the external periodic drift are maximum
at a frequency proportional to the amplitude of the field. In the nonintegrable
case, we show that depending on the field frequency a sharp transition is
observed between a Poisson-limit work distribution at high frequencies toward a
normal work distribution at low frequencies.Comment: 10 pages, 13 figure
Quantum repeated interactions and the chaos game
Inspired by the algorithm of Barnsley's chaos game, we construct an open
quantum system model based on the repeated interaction process. We shown that
the quantum dynamics of the appropriate fermionic/bosonic system (in
interaction with an environment) provides a physical model of the chaos game.
When considering fermionic operators, we follow the system's evolution by
focusing on its reduced density matrix. The system is shown to be in a Gaussian
state (at all time ) and the average number of particles is shown to obey
the chaos game equation. Considering bosonic operators, with a system initially
prepared in coherent states, the evolution of the system can be tracked by
investigating the dynamics of the eigenvalues of the annihilation operator.
This quantity is governed by a chaos game-like equation from which different
scenarios emerge.Comment: 21 pages, 8 figue
Quantum Quench from a Thermal Initial State
We consider a quantum quench in a system of free bosons, starting from a
thermal initial state. As in the case where the system is initially in the
ground state, any finite subsystem eventually reaches a stationary thermal
state with a momentum-dependent effective temperature. We find that this can,
in some cases, even be lower than the initial temperature. We also study
lattice effects and discuss more general types of quenches.Comment: 6 pages, 2 figures; short published version, added references, minor
change
Intrathecal trastuzumab: immunotherapy improves the prognosis of leptomeningeal metastases in HER-2+ breast cancer patient
Activity of platinum and cetuximab in cutaneous squamous cell cancer not amenable to curative treatment
Background: Unresectable or metastatic cutaneous squamous cell cancers (cSCCs) are rare but potentially life-threatening diseases. In this setting, systemic therapy has a palliative intent with limited benefit, but there is no established consensus regarding the proper management of this tumour. This retrospective study aimed to review outcomes in patients with non-curable cSCC treated with platinum-based chemotherapy and cetuximab.
Methods: We considered 12 consecutive patients treated between June 2010 and March 2016. All patients had received previous treatment for the local disease.
Results: The overall response rate was 50%, and the disease control rate was 67%. Median progression-free survival and overall survival were 6.6 (95% confidence interval [CI]: 1.9-8.4) and 14.6 (95% CI: 9.4-20.1) months, respectively. The median duration of response was 4.8 months (95% CI: 1.2-5.9). The most frequent toxicities were skin reactions (58%; grade 3: 25%) and anaemia (10%). No grade 4 toxicities were observed.
Conclusions: Cetuximab and platinum-based chemotherapy were shown to be feasible and active in cSCC, with an acceptable toxicity profile, even if with a limited duration of response
Entanglement and correlation functions following a local quench: a conformal field theory approach
We show that the dynamics resulting from preparing a one-dimensional quantum
system in the ground state of two decoupled parts, then joined together and
left to evolve unitarily with a translational invariant Hamiltonian (a local
quench), can be described by means of quantum field theory. In the case when
the corresponding theory is conformal, we study the evolution of the
entanglement entropy for different bi-partitions of the line. We also consider
the behavior of one- and two-point correlation functions. All our findings may
be explained in terms of a picture, that we believe to be valid more generally,
whereby quasiparticles emitted from the joining point at the initial time
propagate semiclassically through the system.Comment: 19 pages, 4 figures, v2 typos corrected and refs adde
Entanglement in spin chains with gradients
We study solvable spin chains where either fields or couplings vary linearly
in space and create a sandwich-like structure of the ground state. We find that
the entanglement entropy between two halves of a chain varies logarithmically
with the interface width. After quenching to a homogeneous critical system, the
entropy grows logarithmically in time in the XX model, but quadratically in the
transverse Ising chain. We explain this behaviour and indicate generalizations
to other power laws.Comment: 16 pages, 11 figures, 2 references adde
Trastuzumab in the Adjuvant Treatment of HER2-Positive Early Breast Cancer Patients: A Meta-Analysis of Published Randomized Controlled Trials
BACKGROUND: Adjuvant trastuzumab therapy has yielded conflicting results for overall survival, concerns about central nervous system (CNS) metastasis, and questions about optimal schedule. Therefore, we carried out a meta-analysis to assess the benefits of concurrent or sequential trastuzumab with adjuvant chemotherapy for early breast cancer patients with HER2-positive tumors. METHODS: Computerized and manual searches were performed to identify randomized clinical trials comparing adjuvant chemotherapy with or without trastuzumab in HER2-positive early breast cancer patients. Odds ratios were used to estimate the association between the addition of trastuzumab to adjuvant chemotherapy and various survival outcomes. The fixed-effects or random-effects model was used to combine data. FINDINGS: With six eligible studies identified, this analysis demonstrated that patients with HER2-positive breast cancer derived benefit in disease-free survival, overall survival, locoregional recurrence and distant recurrence (all P<0.001) from the addition of trastuzumab to adjuvant chemotherapy, whereas trastuzumab did worse in CNS recurrence as compared to the control group (P = 0.018). Furthermore, concomitant use of trastuzumab significantly lowered the hazard of death (P<0.001) but bore a higher incidence of CNS recurrence (P = 0.010), while statistical significance failed to be discerned for either overall survival (P = 0.069) or CNS metastasis (P = 0.374) between the sequential and observation arms. CONCLUSION: This analysis verifies the efficacy of trastuzumab in the adjuvant setting. Additionally, our findings indirectly corroborate the superiority of concurrent trastuzumab to sequential use and also illuminate that prolonged survival is the possible reason for the higher incidence of CNS with trastuzumab versus observation
Abortive Autophagy Induces Endoplasmic Reticulum Stress and Cell Death in Cancer Cells
Autophagic cell death or abortive autophagy has been proposed to eliminate damaged as well as cancer cells, but there remains a critical gap in our knowledge in how this process is regulated. The goal of this study was to identify modulators of the autophagic cell death pathway and elucidate their effects on cellular signaling and function. The result of our siRNA library screenings show that an intact coatomer complex I (COPI) is obligatory for productive autophagy. Depletion of COPI complex members decreased cell survival and impaired productive autophagy which preceded endoplasmic reticulum stress. Further, abortive autophagy provoked by COPI depletion significantly altered growth factor signaling in multiple cancer cell lines. Finally, we show that COPI complex members are overexpressed in an array of cancer cell lines and several types of cancer tissues as compared to normal cell lines or tissues. In cancer tissues, overexpression of COPI members is associated with poor prognosis. Our results demonstrate that the coatomer complex is essential for productive autophagy and cellular survival, and thus inhibition of COPI members may promote cell death of cancer cells when apoptosis is compromised
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