1,038 research outputs found
Novel duality in disorder driven local quantum criticality
We find that competition between random Kondo and random magnetic
correlations results in a quantum phase transition from a local Fermi liquid to
a spin liquid. The local charge susceptibility turns out to have exactly the
same critical exponent as the local spin susceptibility, suggesting novel
duality between the Kondo singlet phase and the critical local moment state
beyond the Landau-Ginzburg-Wilson symmetry breaking framework. This leads us to
propose an enhanced symmetry at the local quantum critical point, described by
an O(4) vector for spin and charge. The symmetry enhancement serves mechanism
of electron fractionalization in critical impurity dynamics, where such
fractionalized excitations are identified with topological excitations
Spin liquids in graphene
We reveal that local interactions in graphene allow novel spin liquids
between the semi-metal and antiferromagnetic Mott insulating phases, identified
with algebraic spin liquid and Z spin liquid, respectively. We argue that
the algebraic spin liquid can be regarded as the two dimensional realization of
one dimensional spin dynamics, where antiferromagnetic correlations show
exactly the same power-law dependence as valence bond correlations. Nature of
the Z spin liquid turns out to be singlet pairing, but time
reversal symmetry is preserved, taking in one valley and
in the other valley. We propose the quantized thermal valley Hall effect as an
essential feature of this gapped spin liquid state. Quantum phase transitions
among the semi-metal, algebraic spin liquid, and Z spin liquid are shown
to be continuous while the transition from the Z spin liquid to the
antiferromagnetic Mott insulator turns out to be the first order. We emphasize
that both algebraic spin liquid and Z spin liquid can be
verified by the quantum Monte Carlo simulation, showing the enhanced symmetry
in the algebraic spin liquid and the quantized thermal valley Hall effect in
the Z spin liquid
Discrimination of SUSY breaking models using single-photon processes at future e+e- linear colliders
We examine the single-photon processes in the frame work of supersymmetric
models at future e+e- linear colliders. According to the recent experimental
achievement, the optimistic polarization degrees for both electron and positron
beams are taken into account to enhance the signal-to-noise ratio revealing the
observable difference between supersymmetry breaking models. The minimal
supergravity model and the minimal SU(5) grand unified model in gaugino
mediation have been examined as examples. We see that after several years of
accummulating data, the difference of the number of single-photon events
between the two models received from the collider would be in excess of three
times the statistical error, providing us the possibility to probe which model
would be realized in nature. The result is well suitable for the future running
of the International Linear Collider.Comment: 14 pages, 4 figures, version to be published in Mod. Phys. Lett.
Competition between Kondo and RKKY correlations in the presence of strong randomness
We propose that competition between Kondo and magnetic correlations results
in a novel universality class for heavy fermion quantum criticality in the
presence of strong randomness. Starting from an Anderson lattice model with
disorder, we derive an effective local field theory in the dynamical mean-field
theory (DMFT) approximation, where randomness is introduced into both
hybridization and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. Performing
the saddle-point analysis in the U(1) slave-boson representation, we reveal its
phase diagram which shows a quantum phase transition from a spin liquid state
to a local Fermi liquid phase. In contrast with the clean limit of the Anderson
lattice model, the effective hybridization given by holon condensation turns
out to vanish, resulting from the zero mean value of the hybridization coupling
constant. However, we show that the holon density becomes finite when variance
of hybridization is sufficiently larger than that of the RKKY coupling, giving
rise to the Kondo effect. On the other hand, when the variance of hybridization
becomes smaller than that of the RKKY coupling, the Kondo effect disappears,
resulting in a fully symmetric paramagnetic state, adiabatically connected with
the spin liquid state of the disordered Heisenberg model. .....
A systematic review of machine learning models for management, prediction and classification of ARDS
Aim: Acute respiratory distress syndrome or ARDS is an acute, severe form of respiratory failure characterised by poor oxygenation and bilateral pulmonary infiltrates. Advancements in signal processing and machine learning have led to promising solutions for classification, event detection and predictive models in the management of ARDS. Method: In this review, we provide systematic description of different studies in the application of Machine Learning (ML) and artificial intelligence for management, prediction, and classification of ARDS. We searched the following databases: Google Scholar, PubMed, and EBSCO from 2009 to 2023. A total of 243 studies was screened, in which, 52 studies were included for review and analysis. We integrated knowledge of previous work providing the state of art and overview of explainable decision models in machine learning and have identified areas for future research. Results: Gradient boosting is the most common and successful method utilised in 12 (23.1%) of the studies. Due to limitation of data size available, neural network and its variation is used by only 8 (15.4%) studies. Whilst all studies used cross validating technique or separated database for validation, only 1 study validated the model with clinician input. Explainability methods were presented in 15 (28.8%) of studies with the most common method is feature importance which used 14 times. Conclusion: For databases of 5000 or fewer samples, extreme gradient boosting has the highest probability of success. A large, multi-region, multi centre database is required to reduce bias and take advantage of neural network method. A framework for validating with and explaining ML model to clinicians involved in the management of ARDS would be very helpful for development and deployment of the ML model
Overcoming Operational Challenges to Ebola Case Investigation in Sierra Leone.
The Ebola virus disease (EVD) epidemic that hit West Africa in 2013 was the worst outbreak of EVD in recorded history. While much has been published regarding the international and national-level EVD responses, there is a dearth of literature on district-level coordination and operational structures, successes, and failures. This article seeks to understand how the EVD response unfolded at the district level, namely the challenges to operationalizing EVD surveillance over the course of the outbreak in Port Loko and Kambia districts of Sierra Leone. We present here GOAL Global's understanding of the fundamental challenges to case investigation operations during the EVD response, including environmental and infrastructural, sociocultural, and political and organizational challenges, with insight complemented by a survey of 42 case investigators. Major challenges included deficiencies in transportation and communication resources, low morale and fatigue among case investigators, mismanagement of data, mistrust among communities, and leadership challenges. Without addressing these operational challenges, technical surveillance solutions are difficult to implement and hold limited relevance, due to the poor quality and quantity of data being collected. The low prioritization of operational needs came at a high cost. To mediate this, GOAL addressed these operational challenges by acquiring critical transportation and communication resources to facilitate case investigation, including vehicles, boats, fuel, drivers, phones, and closed user groups; addressing fatigue and low morale by hiring more case investigators, making timely payments, arranging for time off, and providing meals and personal protective equipment; improving data tracking efforts through standard operating procedures, training, and mentorship to build higher-quality case histories and make it easier to access information; strengthening trust in communities by ensuring familiarity and consistency of case investigators; and improving operational leadership challenges through meetings and regular coordination, establishing an active surveillance strategy in Port Loko, and conducting an after-action review. Resolving or addressing these challenges was of primary importance, and requisite for the implementation of technical epidemiological complements to EVD case investigation
A tidal lung simulation to quantify lung heterogeneity with the Inspired Sinewave Test
We have created a lung simulation to quantify lung heterogeneity from the
results of the inspired sinewave test (IST). The IST is a lung function test
that is non-invasive, non-ionising and does not require patients' cooperation.
A tidal lung simulation is developed to assess this test and also a method is
proposed to calculate lung heterogeneity from IST results. A sensitivity
analysis based on the Morris method and linear regression were applied to
verify and to validate the simulation. Additionally, simulated emphysema and
pulmonary embolism conditions were created using the simulation to assess the
ability of the IST to identify these conditions. Experimental data from five
pigs (pre-injured vs injured) were used for validation. This paper contributes
to the development of the IST. Firstly, our sensitivity analysis reveals that
the IST is highly accurate with an underestimation of about 5% of the simulated
values. Sensitivity analysis suggested that both instability in tidal volume
and extreme expiratory flow coefficients during the test cause random errors in
the IST results. Secondly, the ratios of IST results obtained at two tracer gas
oscillation frequencies can identify lung heterogeneity (ELV60/ELV180 and
Qp60/Qp180). There was dissimilarity between simulated emphysema and pulmonary
embolism (p < 0:0001). In the animal model, the control group had ELV60/ELV180
= 0.58 compared with 0.39 in injured animals (p < 0.0001)
Replacement of freshwater small-size fish by formulated feed in snakehead (Channa striata) aquaculture: Experimental and commercial-scale pond trials, with economic analysis
Traditional snakehead culture in Southeast Asia relies on use of small-size (trash) fish as food, an unsustainable practice. Following development of weaning methods and testing of formulated feed (FF) in laboratory experiments, we conducted feeding trials of FF vs. trash fish (TF) in experimental ponds at Can Tho University (CTU), followed by similar trials on commercial farms in two provinces in Vietnam. CTU pond trials consisted of five treatments (in triplicate), in which TF was replaced by FF in increasing percentages: 0 (control), 25, 50, 75, and 100% replacement of TF by FF (i.e., three treatments had mixed TF/FF diets). Although survival was significantly reduced in the 100% replacement treatment, and growth was significantly reduced in the 75% and 100% replacement treatments, the cost per kg of fish produced was 28–35% less in those high-replacement treatments compared to the 0% replacement treatment. On-farm trials were then conducted at two farms in An Giang and Dong Thap provinces for 6 months with snakehead fed TF only or FF only. At both farms, survival (73–80%) was not significantly different, but growth was significantly better on FF diet at both; however, FF-fed fish at the An Giang farm showed significantly higher levels of abnormal development. Overall production was about twice as high at the An Giang farm as at Dong Thap, but significantly greater production by FF-fed fish vs. TF-fed fish was only seen at Dong Thap. Sensory evaluation by a tasting panel found no difference in product quality between FF-fed fish, TF-fed fish, and a commercial sample bought in the market. Economic analysis indicated that profits were higher for FF-fed fish from both farms, although production costs and sales varied greatly, reflecting market differences in the two provinces
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