405 research outputs found
Fra utilitas e salubritas: esempi maltesi di bonifiche con anfore
No full textThis study examines for the first time tree cases of inverted amphorae used like soils improvement under floors of domus in Melite at the Roman times. The finality of inverted amphorae is once again recognized, based on studies' experiences of authior, througt analysis of lithological soils characters. In the first book of this Collection (Itinera ,1, 1996) the author offered some technical factors for analysis of the possible function of this biulding method and now, using the same method, i.e. with regard to the natural state of land, their statis lift, etc., has been possible to understand the aim of amphorae structures in Roman age
From stochastic Hamiltonian to quantum simulation: exploring memory effects in exciton dynamics
No full textThe unraveling of open quantum system dynamics in terms of stochastic quantum trajectories offers a picture of open system dynamics that consistently considers memory effects stemming from the finite correlation time of environment fluctuations. These fluctuations significantly influence the coherence and energy transport properties of excitonic systems. When their correlation time is comparable to the timescale of the Hamiltonian evolution, it leads to the departure of open system dynamics from the Markovian limit. In this work, we leverage the unraveling of exciton dynamics through stochastic Hamiltonian propagators to design quantum circuits that simulate exciton transport, capturing finite memory effects. In addition to enabling the synthesis of parametrizable quantum circuits, stochastic unitary propagators provide a transparent framework for investigating non-Markovian effects on exciton transport. Our analysis reveals a nuanced relationship between environment correlation time and transport efficiency, identifying a regime of 'memory-assisted' quantum transport where time-correlated fluctuations allow the system to reach higher efficiency. However, this property is not universal and can only be realized in conjunction with specific features of the system Hamiltonian
Strategies to simulate dephasing-assisted quantum transport on digital quantum computers
No full textSimulating charge and energy transfer in extended molecular networks requires an effective model to include the environment because it significantly affects the quantum dynamics. A prototypical effect known as environment-assisted quantum transport (ENAQT) consists in the enhancement of the transfer efficiency by the interaction with an environment. A simple description of this phenomenon is obtained by a quantum master equation describing a quantum walk over the molecular network in the presence of inter-site decoherence. We consider the problem of simulating the dynamics underlying ENAQT in a digital quantum computer. Two different quantum algorithms are introduced, the first one based on stochastic Hamiltonians and the second one based on a collision scheme. We test both algorithms by simulating ENAQT in a small molecular network on a quantum computer emulator and provide a comparative analysis of the two approaches. Both algorithms can be implemented in a memory efficient encoding with the number of required qubits scaling logarithmically with the size of the simulated system while the number of gates increases quadratically. We discuss the algorithmic quantum trajectories generated by the two simulation strategies showing that they realize distinct unravellings of the site-dephasing master equation. In our approach, the non-unitary dynamics of the open system is obtained through effective representations of the environment, paving the way to digital quantum simulations of quantum transport influenced by structured environments
Simulating action-2D electronic spectroscopy of quantum dots: insights on the exciton and biexciton interplay from detection-mode and time-gating
No full textA Quantum Algorithm from Response Theory: Digital Quantum Simulation of Two-Dimensional Electronic Spectroscopy
No full textMultidimensional optical spectroscopies are powerful techniques to investigate energy transfer pathways in natural and artificial systems. Because of the high information content of the spectra, numerical simulations of the optical response are of primary importance to assist the interpretation of spectral features. However, the increasing complexity of the investigated systems and their quantum dynamics call for the development of novel simulation strategies. In this work, we consider using digital quantum computers. By combining quantum dynamical simulation and nonlinear response theory, we present a quantum algorithm for computing the optical response of molecular systems. The quantum advantage stems from the efficient quantum simulation of the dynamics governed by the molecular Hamiltonian, and it is demonstrated by explicitly considering exciton-vibrational coupling. The protocol is tested on a near-term quantum device, providing the digital quantum simulation of the linear and nonlinear response of simple molecular models
MODELS AND QUANTUM ALGORITHMS FOR OPEN SYSTEM DYNAMICS: THE CASE STUDY OF EXCITON TRANSPORT IN MOLECULAR NETWORKS
No full textAs physical systems of chemical interest are rarely isolated, molecular processes should always be intended within the framework of open system dynamics. Notable examples are charge and energy transfer in molecular networks, for which intense theoretical and experimental research has highlighted the central role of the interplay between the system Hamiltonian and decoherences due to the interaction with the environment. At intermediate system-environment interaction strengths, the cooperation between coherent and incoherent dynamics can result in a prototypical effect called environment-assisted quantum transport (ENAQT), which consists of the enhancement of transport efficiency. ENAQT is believed to play a primary part in the high efficiency of natural light-harvesting complexes. A comprehensive understanding and powerful simulation strategies for these dynamical phenomena could help us, for example, in the design of artificial devices, based on the engineering of materials and their environment, for high-performance cells for photovoltaic applications. However, the simulation of open quantum systems poses the theoretical challenge of devising an adequate equation of motion for the dynamics and a computational strategy for its solution, which becomes prohibitively difficult for classical computers when handling large quantum systems.
Thanks to the theoretical and experimental scientific advances of the last decades, we are now at the dawn of the so-called second quantum revolution that promises novel technological tools based on harnessing quantum coherence. Quantum computers, i.e., physical systems manipulated at the quantum level with high precision, are concrete examples. In recent years, quantum computers have already demonstrated they can tackle some complex problems considered intractable by classical computers: the so-called quantum advantage. The simulation of quantum systems has always been a strong motivation behind the development of quantum computers, as they are expected to provide advantages in dealing with large systems based on their huge computational space. However, despite its importance, the simulation of open system dynamics has received relatively little attention. One of the reasons is the non-trivial challenge of reproducing the evolution of open quantum systems in the framework of quantum circuits.
In this thesis, we approach the study of open system dynamics by drawing two parallel paths. On the one hand, we intend to explore in detail some salient features of quantum transport in molecular networks. To do so, we will critically analyse existing models for open system dynamics, ranging from Markovian to non-Markovian regime, from weak to strong coupling and from infinite to finite temperature. On the other hand, we consider the problem of simulating the dynamics underlying ENAQT with digital quantum computers. An algorithmic package is developed to implement the dynamics in different conditions. The algorithms are designed with two different strategies, the first one based on stochastic Hamiltonians and the second one based on a collision model. We demonstrate the potentiality of our algorithms by simulating ENAQT on a quantum computer emulator and provide a comparative analysis of the two approaches. Both algorithmic strategies can be implemented in a memory-efficient encoding with the number of required qubits scaling logarithmically with the size of the simulated system, while the number of gates scales polynomially depending on the target environmental conditions. We discuss the algorithmic quantum trajectories generated during the execution of the algorithms showing that they realize distinct unravellings of the dynamics of the open system.As physical systems of chemical interest are rarely isolated, molecular processes should always be intended within the framework of open system dynamics. Notable examples are charge and energy transfer in molecular networks, for which intense theoretical and experimental research has highlighted the central role of the interplay between the system Hamiltonian and decoherences due to the interaction with the environment. At intermediate system-environment interaction strengths, the cooperation between coherent and incoherent dynamics can result in a prototypical effect called environment-assisted quantum transport (ENAQT), which consists of the enhancement of transport efficiency. ENAQT is believed to play a primary part in the high efficiency of natural light-harvesting complexes. A comprehensive understanding and powerful simulation strategies for these dynamical phenomena could help us, for example, in the design of artificial devices, based on the engineering of materials and their environment, for high-performance cells for photovoltaic applications. However, the simulation of open quantum systems poses the theoretical challenge of devising an adequate equation of motion for the dynamics and a computational strategy for its solution, which becomes prohibitively difficult for classical computers when handling large quantum systems.
Thanks to the theoretical and experimental scientific advances of the last decades, we are now at the dawn of the so-called second quantum revolution that promises novel technological tools based on harnessing quantum coherence. Quantum computers, i.e., physical systems manipulated at the quantum level with high precision, are concrete examples. In recent years, quantum computers have already demonstrated they can tackle some complex problems considered intractable by classical computers: the so-called quantum advantage. The simulation of quantum systems has always been a strong motivation behind the development of quantum computers, as they are expected to provide advantages in dealing with large systems based on their huge computational space. However, despite its importance, the simulation of open system dynamics has received relatively little attention. One of the reasons is the non-trivial challenge of reproducing the evolution of open quantum systems in the framework of quantum circuits.
In this thesis, we approach the study of open system dynamics by drawing two parallel paths. On the one hand, we intend to explore in detail some salient features of quantum transport in molecular networks. To do so, we will critically analyse existing models for open system dynamics, ranging from Markovian to non-Markovian regime, from weak to strong coupling and from infinite to finite temperature. On the other hand, we consider the problem of simulating the dynamics underlying ENAQT with digital quantum computers. An algorithmic package is developed to implement the dynamics in different conditions. The algorithms are designed with two different strategies, the first one based on stochastic Hamiltonians and the second one based on a collision model. We demonstrate the potentiality of our algorithms by simulating ENAQT on a quantum computer emulator and provide a comparative analysis of the two approaches. Both algorithmic strategies can be implemented in a memory-efficient encoding with the number of required qubits scaling logarithmically with the size of the simulated system, while the number of gates scales polynomially depending on the target environmental conditions. We discuss the algorithmic quantum trajectories generated during the execution of the algorithms showing that they realize distinct unravellings of the dynamics of the open system
The Gallina of New Mexico: a culture of violence?
No full text2012 Summer.Includes bibliographical references.This thesis research examines the interpersonal violence occurring within the Gallina cultural group of the Ancestral Pueblo tradition in north-central New Mexico (A.D. 1050-1250/1300). In order to understand actual events of violence, the skeletal material of the Gallina was examined. In-depth analysis of all the remains associated with the Gallina allowed for the creation of a comprehensive view of the age-at-death and sex distribution. Additionally, the use of standard osteological procedures was used to identify and describe traumatic injuries found on the skeletal material attributed to interpersonal violence. These traumas, along with the age-at-death and sex distribution made it possible to compare the Gallina to other samples to determine how prevalent Gallina violence was within the greater Ancestral Pueblo tradition and hypothesize explanations for the violence that are most plausible. The Gallina sample consists of 142 individuals; there are slightly more males than females. There are 86 adults and 36 sub-adults, with a majority of the individuals between the ages of 20 and 40. Of a minimum of 142 individuals, 52 exhibit traumatic injury, though only 17 individuals show clear evidence of interpersonal violence. Twenty-five have been burned, which may or may not have been due to violent events. This is a conservative number as the completeness of the individuals varies and several individuals are fragmented or are missing parts of the skeleton such that if trauma was there it was not observable. This sample demonstrates at least one instance of each of five main types of trauma (blunt force, sharp force, sharp-blunt force, projectile, and cremation), with blunt force trauma and cremation showing the highest frequencies. The violence observed among the Gallina, when compared to that in the La Plata River Valley and the Southwest Basin and Range Region show that the Gallina experienced slightly more violent events, though not overwhelmingly so. As for hypotheses to explain the Gallina violence, domestic violence against women, witchcraft execution, and cannibalism were ruled out as the Gallina did not exhibit all the characteristics of such events. The most logical explanation for the interpersonal violence observed among the Gallina was warfare/conflict, though whether this is intergroup or intragroup violence remains to be explored more carefully
Swallowing Outcomes in Open Partial Horizontal Laryngectomy Type I and Endoscopic Supraglottic Laryngectomy: A Comparative Study
No full textBackground: Effective swallowing represents the main challenge in supraglottic laryngectomy. This study aimed to assess swallowing outcome comparing endoscopic supraglottic laryngectomy (ESL) and open partial horizontal laryngectomy type I (OPHL I). Methods: A retrospective study was carried out on 20 patients that underwent supraglottic laryngectomy from 2015 to 2021: 10 underwent ESL (group A) and 10 underwent OPHL I (Group B). Patients underwent fiberoptic endoscopic evaluation of swallowing (FEES) 3 months and 12 months after surgery and videofluoroscopy swallowing studies (VFSS) 12 months after surgery. A Swallowing Outcome After Laryngectomy (SOAL) questionnaire was administered to patients to assess their life quality. Results: A naso-gastric tube was placed in two patients of Group A and in all patients of Group B. Tracheostomy was performed in two patients of Group A and in all patients in Group B and it has been closed in 100% of them. According to Donzelli’s scale, FEES and VFSS showed better results in Group A at 3 months, while at 12 months they did not show statistically significant differences between ESL and OPHL I in terms of laryngeal penetration and aspiration. The SOAL questionnaire showed satisfactory life quality. Conclusion: Swallowing evaluation by FEES and VFSS did not demonstrate statistically significant differences at 12 months post-op between two surgeries, although ESL showed less cases of laryngeal penetration and aspiration at 3 months post-op. Anyway, good results of any surgery depend on careful patient selection and the surgeon’s experience
TOSSICITA' ACUTA, INDIVIDUALE E BINARIA, DI QUATTRO SULFAMIDICI DI USO VETERINARIO, SUL MICROCROSTACEO Daphnia magna.
No full textThe toxicities of sulfamethazine, sulfadimethoxine, sulfadiazine, and sulfamerazine were determined individually and in paired mixtures against Daphnia magna.Sulfamerazine (EC50 = 277 mg/L) was the least toxic and sulfamethazine (EC50 = 202 mg/L) the most toxic. Eight out of the nine mixture tested produced a statistically supported less than additive toxicity (isobologram method), posing a lower toxicological hazard to Daphnia magna
than the respective individual sulfonamides. The use of solvents to produce a suitably concentrated stock solution is also discussed
Unifying Nonlinear Response and Incoherent Mixing in Action-2D Electronic Spectroscopy
No full textAction-detection has expanded the scope and applicability of 2D electronic spectroscopy, while posing new challenges for the unambiguous interpretation of spectral features. In this context, identifying the origin of cross-peaks at early waiting times is not trivial, and incoherent mixing is often invoked as an unwanted contribution masking the nonlinear signal. In this work, we elaborate on the relation between the nonlinear response and the incoherent mixing contribution by analyzing the action signal in terms of one- and two-particle observables. Considering a weakly interacting molecular dimer, we show how cross-peaks at early waiting times, reflecting exciton-exciton annihilation dynamics, can be equivalently interpreted as arising from incoherent mixing. This equivalence, on the one hand, highlights the information content of spectral features related to incoherent mixing and, on the other hand, provides an efficient numerical scheme to simulate the action response of weakly interacting systems
- …
