69 research outputs found
Statistical mechanics of the Cluster-Ising model
We study a Hamiltonian system describing a three-spin-1/2 cluster-like
interaction competing with an Ising-like anti-ferromagnetic interaction. We
compute free energy, spin correlation functions and entanglement both in the
ground and in thermal states. The model undergoes a quantum phase transition
between an Ising phase with a nonvanishing magnetization and a cluster phase
characterized by a string order. Any two-spin entanglement is found to vanish
in both quantum phases because of a nontrivial correlation pattern.
Neverthless, the residual multipartite entanglement is maximal in the cluster
phase and dependent on the magnetization in the Ising phase. We study the block
entropy at the critical point and calculate the central charge of the system,
showing that the criticality of the system is beyond the Ising universality
class.Comment: To be published in Physical Review
SWIPE: a bolometric polarimeter for the Large-Scale Polarization Explorer
The balloon-borne LSPE mission is optimized to measure the linear
polarization of the Cosmic Microwave Background at large angular scales. The
Short Wavelength Instrument for the Polarization Explorer (SWIPE) is composed
of 3 arrays of multi-mode bolometers cooled at 0.3K, with optical components
and filters cryogenically cooled below 4K to reduce the background on the
detectors. Polarimetry is achieved by means of large rotating half-wave plates
and wire-grid polarizers in front of the arrays. The polarization modulator is
the first component of the optical chain, reducing significantly the effect of
instrumental polarization. In SWIPE we trade angular resolution for
sensitivity. The diameter of the entrance pupil of the refractive telescope is
45 cm, while the field optics is optimized to collect tens of modes for each
detector, thus boosting the absorbed power. This approach results in a FWHM
resolution of 1.8, 1.5, 1.2 degrees at 95, 145, 245 GHz respectively. The
expected performance of the three channels is limited by photon noise,
resulting in a final sensitivity around 0.1-0.2 uK per beam, for a 13 days
survey covering 25% of the sky.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation
Engineers. One print or electronic copy may be made for personal use only.
Systematic reproduction and distribution, duplication of any material in this
paper for a fee or for commercial purposes, or modification of the content of
the paper are prohibite
The Large-Scale Polarization Explorer (LSPE)
The LSPE is a balloon-borne mission aimed at measuring the polarization of
the Cosmic Microwave Background (CMB) at large angular scales, and in
particular to constrain the curl component of CMB polarization (B-modes)
produced by tensor perturbations generated during cosmic inflation, in the very
early universe. Its primary target is to improve the limit on the ratio of
tensor to scalar perturbations amplitudes down to r = 0.03, at 99.7%
confidence. A second target is to produce wide maps of foreground polarization
generated in our Galaxy by synchrotron emission and interstellar dust emission.
These will be important to map Galactic magnetic fields and to study the
properties of ionized gas and of diffuse interstellar dust in our Galaxy. The
mission is optimized for large angular scales, with coarse angular resolution
(around 1.5 degrees FWHM), and wide sky coverage (25% of the sky). The payload
will fly in a circumpolar long duration balloon mission during the polar night.
Using the Earth as a giant solar shield, the instrument will spin in azimuth,
observing a large fraction of the northern sky. The payload will host two
instruments. An array of coherent polarimeters using cryogenic HEMT amplifiers
will survey the sky at 43 and 90 GHz. An array of bolometric polarimeters,
using large throughput multi-mode bolometers and rotating Half Wave Plates
(HWP), will survey the same sky region in three bands at 95, 145 and 245 GHz.
The wide frequency coverage will allow optimal control of the polarized
foregrounds, with comparable angular resolution at all frequencies.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation
Engineers. One print or electronic copy may be made for personal use only.
Systematic reproduction and distribution, duplication of any material in this
paper for a fee or for commercial purposes, or modification of the content of
the paper are prohibite
Insight from an Italian Delphi Consensus on EVAR feasibility outside the instruction for use: the SAFE EVAR Study
BACKGROUND: The SAfety and FEasibility of standard EVAR outside the instruction for use (SAFE-EVAR) Study was designed to define the attitude of Italian vascular surgeons towards the use of standard endovascular repair (EVAR) for infrarenal abdominal aortic aneurysm (AAA) outside the instruction for use (IFU) through a Delphi consensus endorsed by the Italian Society of Vascular and Endovascular Surgery (Societa Italiana di Chirurgia Vascolare ed Endovascolare - SICVE). METHODS: A questionnaire consisting of 26 statements was developed, validated by an 18 -member Advisory Board, and then sent to 600 Italian vascular surgeons. The Delphi process was structured in three subsequent rounds which took place between April and June 2023. In the first two rounds, respondents could indicate one of the following five degrees of agreement: 1) strongly agree; 2) partially agree; 3) neither agree nor disagree; 4) partially disagree; 5) strongly disagree; while in the third round only three different choices were proposed: 1) agree; 2) neither agree nor disagree; 3) disagree. We considered the consensus reached when >70% of respondents agreed on one of the options. After the conclusion of each round, a report describing the percentage distribution of the answers was sent to all the participants. RESULTS: Two -hundred -forty-four (40.6%) Italian Vascular Surgeons agreed to participate the first round of the Delphi Consensus; the second and the third rounds of the Delphi collected 230 responders (94.3% of the first -round responders). Four statements (15.4%) reached a consensus in the first rounds. Among the 22 remaining statements, one more consensus (3.8%) was achieved in the second round. Finally, seven more statements (26.9%) reached a consensus in the simplified last round. Globally, a consensus was reached for almost half of the proposed statements (46.1%). CONCLUSIONS: The relatively low consensus rate obtained in this Delphi seems to confirm the discrepancy between Guideline recommendations and daily clinical practice. The data collected could represent the source for a possible guidelines' revision and the proposal of specific Good Practice Points in all those aspects with only little evidence available
MORFEO enters final design phase
MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations, formerly
MAORY), the MCAO system for the ELT, will provide diffraction-limited optical
quality to the large field camera MICADO. MORFEO has officially passed the
Preliminary Design Review and it is entering the final design phase. We present
the current status of the project, with a focus on the adaptive optics system
aspects and expected milestones during the next project phase
The LIFE TRIAD of emergency general surgery
Emergency General Surgery (EGS) was identified as multidisciplinary surgery performed for traumatic and non-traumatic acute conditions during the same admission in the hospital by general emergency surgeons and other specialists. It is the most diffused surgical discipline in the world. To live and grow strong EGS necessitates three fundamental parts: emergency and elective continuous surgical practice, evidence generation through clinical registries and data accrual, and indications and guidelines production: the LIFE TRIAD.Peer reviewe
Detection chain and electronic readout of the QUBIC instrument
The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10â»ÂčⶠW/âHz
Detection chain and electronic readout of the QUBIC instrument
The Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10â»ÂčⶠW/âHz
A Qualitative Exploration of the Use of Contraband Cell Phones in Secured Facilities
Offenders accepting contraband cell phones in secured facilities violate state corrections law, and the possession of these cell phones is a form of risk taking behavior. When offenders continue this risky behavior, it affects their decision making in other domains where they are challenging authorities; and may impact the length of their incarceration. This qualitative phenomenological study examined the lived experience of ex-offenders who had contraband cell phones in secured correctional facilities in order to better understand their reasons for taking risks with contraband cell phones. The theoretical foundation for this study was Trimpop\u27s risk-homeostasis and risk-motivation theories that suggest an individual\u27s behaviors adapt to negotiate between perceived risk and desired risk in order to achieve satisfaction. The research question explored beliefs and perceptions of ex-offenders who chose to accept the risk of using contraband cell phones during their time in secured facilities. Data were collected anonymously through recorded telephone interviews with 8 male adult ex-offenders and analyzed using thematic content analysis. Findings indicated participants felt empowered by possession of cell phones in prison, and it was an acceptable risk to stay connected to family out of concern for loved ones. The study contributes to social change by providing those justice system administrators, and prison managers responsible for prison cell phone policies with more detailed information about the motivations and perspectives of offenders in respect to using contraband cell phones while imprisoned in secured facilities
Diversity and ethics in trauma and acute care surgery teams: results from an international survey
Background Investigating the context of trauma and acute care surgery, the article aims at understanding the factors that can enhance some ethical aspects, namely the importance of patient consent, the perceptiveness of the ethical role of the trauma leader, and the perceived importance of ethics as an educational subject. Methods The article employs an international questionnaire promoted by the World Society of Emergency Surgery. Results Through the analysis of 402 fully filled questionnaires by surgeons from 72 different countries, the three main ethical topics are investigated through the lens of gender, membership of an academic or non-academic institution, an official trauma team, and a diverse group. In general terms, results highlight greater attention paid by surgeons belonging to academic institutions, official trauma teams, and diverse groups. Conclusions Our results underline that some organizational factors (e.g., the fact that the team belongs to a university context or is more diverse) might lead to the development of a higher sensibility on ethical matters. Embracing cultural diversity forces trauma teams to deal with different mindsets. Organizations should, therefore, consider those elements in defining their organizational procedures. Level of evidence Trauma and acute care teams work under tremendous pressure and complex circumstances, with their members needing to make ethical decisions quickly. The international survey allowed to shed light on how team assembly decisions might represent an opportunity to coordinate team member actions and increase performance
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