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Book ; Online: Error Correction for Reliable Quantum Computing

Fuentes, Patricio

2022

Abstract: Quantum computers herald the arrival of a new era in which previously intractable computational problems will be solved efficiently. However, quantum technology is held down by decoherence, a phenomenon that is omnipresent in the quantum paradigm and ... ...

Abstract	Quantum computers herald the arrival of a new era in which previously intractable computational problems will be solved efficiently. However, quantum technology is held down by decoherence, a phenomenon that is omnipresent in the quantum paradigm and that renders quantum information useless when left unchecked. The science of quantum error correction, a discipline that seeks to combine and protect quantum information from the effects of decoherence using structures known as codes, has arisen to meet this challenge. Stabilizer codes, a particular subclass of quantum codes, have enabled fast progress in the field of quantum error correction by allowing parallels to be drawn with the widely studied field of classical error correction. This has resulted in the construction of the quantum counterparts of well-known capacity-approaching classical codes like sparse codes and quantum turbo codes. However, quantum codes obtained in this manner do not entirely evoke the stupendous error correcting abilities of their classical counterparts. This occurs because classical strategies ignore important differences between the quantum and classical paradigms, an issue that needs to be addressed if quantum error correction is to succeed in its battle with decoherence. In this dissertation we study a phenomenon exclusive to the quantum paradigm, known as degeneracy, and its effects on the performance of sparse quantum codes. Furthermore, we also analyze and present methods to improve the performance of a specific family of sparse quantum codes in various different scenarios. Comment: PhD Dissertation. Defended on February 14 2022
Keywords	Quantum Physics ; Electrical Engineering and Systems Science - Systems and Control
Subject code	190
Publishing date	2022-02-17
Publishing country	us
Document type	Book ; Online
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Article ; Online: Clinical diagnosis in preclinical stage of Alzheimer's disease.

Fuentes, Patricio

Archives of medical research

2012 Volume 43, Issue 8, Page(s) 667–670

Abstract: Preclinical diagnosis of Alzheimer's disease using biomarkers has become an area of great interest for both clinicians and researchers because, among other advantages, this would increase the response to new disease-modifying drugs. However, difficulties ...

Abstract	Preclinical diagnosis of Alzheimer's disease using biomarkers has become an area of great interest for both clinicians and researchers because, among other advantages, this would increase the response to new disease-modifying drugs. However, difficulties with compliance and economic costs marginalize many countries worldwide that do not have access to this new type of diagnosis. The opportunity exists to refine the conventional clinical method, without using biomarkers, to attempt an earlier diagnosis as there is information that supports the potential utility of a focused clinical interview, observation of gait and use of more demanding memory tests.
MeSH term(s)	Alzheimer Disease/classification ; Alzheimer Disease/diagnosis ; Alzheimer Disease/economics ; Biomarkers/analysis ; Cognition ; Early Diagnosis ; Gait ; Humans ; Interviews as Topic ; Memory ; Neurologic Examination ; Neuropsychological Tests
Chemical Substances	Biomarkers
Language	English
Publishing date	2012-11
Publishing country	United States
Document type	Journal Article ; Review
ZDB-ID	1156844-6
ISSN	1873-5487 ; 0188-4409 ; 0188-0128
ISSN (online)	1873-5487
ISSN	0188-4409 ; 0188-0128
DOI	10.1016/j.arcmed.2012.10.014
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Article: An update on aging and dementia in Chile.

Fuentes, Patricio / Albala, Cecilia

Dementia & neuropsychologia

2017 Volume 8, Issue 4, Page(s) 317–322

Abstract: Chile is in an advanced demographic transition stage with the population over 60 years of age representing 15% of the total population and whose number of elderly has more than doubled between 1990 and 2014. Rapid economic advancement has promoted ... ...

Abstract	Chile is in an advanced demographic transition stage with the population over 60 years of age representing 15% of the total population and whose number of elderly has more than doubled between 1990 and 2014. Rapid economic advancement has promoted significant changes in social organization to which the country is not accustomed. The mental health problems of the elderly are particularly challenging to the country's present social and health structures. The prevalence of dementia in people over 60 years exceeds 8% and is even higher in the rural population. There is more training on dementia in the local medical and scientific community, increased awareness within the civilian community but insufficient responsiveness from the state to the broad diagnostic and therapeutic requirements of patients and caregivers. The objective of the present study was to provide an update of the information on dementia in the context of the ageing process in Chile.
Language	English
Publishing date	2017-08-22
Publishing country	Brazil
Document type	Journal Article ; Review
ISSN	1980-5764
ISSN	1980-5764
DOI	10.1590/S1980-57642014DN84000003
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Article ; Online: Comparison of complications and reoperations in AO/OTA 43.C3 pilon fractures treated with conventional ORIF versus minimally invasive hexapod ring fixation.

Bastías, Gonzalo F / Sepúlveda, Sebastián / Bruna, Sergio / Contreras, Martin / Hube, Maximiliano / Cuchacovich, Natalio / Bergeret, Juan Pedro / Fuentes, Patricio

Injury

2023 Volume 54 Suppl 6, Page(s) 110884

Abstract: Introduction: Controversy exists regarding the optimal management of AO/OTA 43. C3 pilon fractures. Open reduction and internal fixation (ORIF) is the gold standard treatment, but serious soft tissue and infectious complications have been previously ... ...

Abstract	Introduction: Controversy exists regarding the optimal management of AO/OTA 43. C3 pilon fractures. Open reduction and internal fixation (ORIF) is the gold standard treatment, but serious soft tissue and infectious complications have been previously reported. Minimally invasive strategies using hexapod ring fixation (HRF) with supplemental limited internal fixation have been used to reduce the incidence of complications. Previous studies have included heterogeneous types of pilon fractures, with non-comminuted injuries being more likely to be treated with ORIF and complex fractures receiving HRF treatment. To our knowledge, no studies have compared the complications and reoperation rates between ORIF and HRF exclusively for C3 fractures. Methods: Retrospective study comparing 53 patients treated for AO/OTA 43.C3 pilon fracture with ORIF or HRF in a trauma level I center with at least a two-year follow-up. Patients treated between January 2015 and January 2019 received ORIF and those treated between January 2019 and January 2021 received HRF. Complications were divided into two groups: minor (superficial infection and malalignment) and major (non-union, deep infection, and amputation). Reoperations, prevalence of ankle osteoarthritis, and requirement for ankle arthrodesis/total ankle replacement were registered. Results: We included 30 and 23 patients in the ORIF and HRF groups, respectively. The overall complication rate was similar in both groups, with 50% and 56,5% of the patients having complications in the ORIF and HRF groups, respectively (p:0,63). Minor complications were significantly more prevalent in the HRF group (p<0,001) whilst the ORIF group had a significantly higher rate of major complications (p<0,01). Superficial infections were highly prevalent in the HRF group (47,8%), as they were related to half-pin or K-wire infections. Deep infection was present only in the ORIF group, with 20% of the patients developing this major complication (p:0,03). Non-union rate, reoperations, ankle osteoarthritis, and the need for arthrodesis or ankle replacement showed no significant differences. Conclusion: In AO/OTA 43.C3 fractures, HRF is safe and effective, achieving high union rates with a significantly lower rate of major complications compared to ORIF. According to our results, ORIF should be used cautiously for these types of fractures, considering the increased risk of deep infection.
MeSH term(s)	Humans ; Treatment Outcome ; Follow-Up Studies ; Reoperation ; Retrospective Studies ; Ankle Injuries/surgery ; Bone Plates ; Ankle Fractures/diagnostic imaging ; Ankle Fractures/surgery ; Fracture Fixation, Internal/methods ; Tibial Fractures/surgery ; Osteoarthritis/surgery
Language	English
Publishing date	2023-04-14
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	218778-4
ISSN	1879-0267 ; 0020-1383
ISSN (online)	1879-0267
ISSN	0020-1383
DOI	10.1016/j.injury.2023.110884
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Zs.A 778: Show issues			Location: Je nach Verfügbarkeit (siehe Angabe bei Bestand) bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular Jg. 1995 - 2021: Lesesall (1.OG) ab Jg. 2022: Lesesaal (EG)
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Article ; Online: Treatment of Severe Rigid Posttraumatic Equinus Deformity With Gradual Deformity Correction and Arthroscopic Ankle Arthrodesis.

Fuentes, Patricio / Cuchacovich, Natalio / Gutierrez, Paulina / Hube, Maximiliano / Bastías, Gonzalo F

Foot & ankle international

2021 Volume 42, Issue 12, Page(s) 1525–1535

Abstract: Background: Posttraumatic ankle equinus is associated with rigid deformity, poor skin condition, and multiple prior surgeries. Open acute correction has been described using osteotomies, talectomy, and arthrodesis, but concerns exist about skin ... ...

Abstract	Background: Posttraumatic ankle equinus is associated with rigid deformity, poor skin condition, and multiple prior surgeries. Open acute correction has been described using osteotomies, talectomy, and arthrodesis, but concerns exist about skin complications, neurologic alterations, secondary limb discrepancy, and bone loss. Gradual correction using a multiplanar ring fixator and arthroscopic ankle arthrodesis (AAA) may decrease these complications. Methods: We retrospectively reviewed patients undergoing correction of posttraumatic rigid equinus with at least 1 year of follow-up after frame removal. The procedure consisted of percutaneous Achilles lengthening, gradual equinus correction using a multiplanar ring fixator, and AAA retaining the fixator in compression with screw augmentation. Frame removal depended on signs of union on the computed tomography scan. Visual analog scale (VAS) and Foot Function Index (FFI) scores were assessed as well as preoperative and postoperative x-rays. Complications were noted throughout the follow-up period. Results: Five patients were treated with a mean age of 35 years and mean follow-up of 31 months. Deformities were gradually corrected into a plantigrade foot over an average duration of 6 weeks. Union was achieved in all patients with a mean time of an additional 25 weeks, for a mean total frame time of 31 weeks. The mean preoperative tibiotalar angle was 151 degrees and was corrected to 115 degrees. FFI score improved from a mean of 87 to 24 and VAS from 8 to 2. Conclusion: Posttraumatic rigid equinus can be treated effectively using gradual correction followed by integrated AAA in a safe and reproducible manner. Patients in this series had excellent functional, radiological, and satisfaction results. Level of evidence: Level IV, retrospective case series.
MeSH term(s)	Adult ; Ankle ; Ankle Joint/diagnostic imaging ; Ankle Joint/surgery ; Arthrodesis ; Equinus Deformity/etiology ; Equinus Deformity/surgery ; Humans ; Retrospective Studies ; Treatment Outcome
Language	English
Publishing date	2021-06-18
Publishing country	United States
Document type	Journal Article
ZDB-ID	1183283-6
ISSN	1944-7876 ; 1071-1007
ISSN (online)	1944-7876
ISSN	1071-1007
DOI	10.1177/10711007211018201
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Book ; Online: Performance of surface codes in realistic quantum hardware

iOlius, Antonio deMarti / Martinez, Josu Etxezarreta / Fuentes, Patricio / Crespo, Pedro M. / Garcia-Frias, Javier

2022

Abstract: Surface codes are generally studied based on the assumption that each of the qubits that make up the surface code lattice suffers noise that is independent and identically distributed (i.i.d.). However, real benchmarks of the individual relaxation ($T_1$) ...

Abstract	Surface codes are generally studied based on the assumption that each of the qubits that make up the surface code lattice suffers noise that is independent and identically distributed (i.i.d.). However, real benchmarks of the individual relaxation ($T_1$) and dephasing ($T_2$) times of the constituent qubits of state-of-the-art quantum processors have recently shown that the decoherence effects suffered by each particular qubit actually vary in intensity. In consequence, in this article we introduce the independent non-identically distributed (i.ni.d.) noise model, a decoherence model that accounts for the non-uniform behaviour of the docoherence parameters of qubits. Additionally, we use the i.ni.d model to study how it affects the performance of a specific family of Quantum Error Correction (QEC) codes known as planar codes. For this purpose we employ data from four state-of-the-art superconducting processors: ibmq\_brooklyn, ibm\_washington, Zuchongzhi and Rigetti Aspen-M-1. Our results show that the i.i.d. noise assumption overestimates the performance of surface codes, which can suffer up to $95\%$ performance decrements in terms of the code pseudo-threshold when they are subjected to the i.ni.d. noise model. Furthermore, we consider and describe two methods which enhance the performance of planar codes under i.ni.d. noise. The first method involves a so-called re-weighting process of the conventional minimum weight perfect matching (MWPM) decoder, while the second one exploits the relationship that exists between code performance and qubit arrangement in the surface code lattice. The optimum qubit configuration derived through the combination of the previous two methods can yield planar code pseudo-threshold values that are up to $650\%$ higher than for the traditional MWPM decoder under i.ni.d. noise. Comment: Includes supplementary material (19 pages total)
Keywords	Quantum Physics ; Electrical Engineering and Systems Science - Systems and Control
Subject code	612
Publishing date	2022-03-29
Publishing country	us
Document type	Book ; Online
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Article ; Online: Interventional Study to Evaluate the Clinical Effects and Safety of the Nutraceutical Compound BrainUp-10® in a Cohort of Patients with Alzheimer's Disease: A Multicenter, Randomized, Double-Blind, and Placebo-Controlled Trial.

Guzman-Martinez, Leonardo / Farías, Gonzalo A / Tapia, José P / Sánchez, María P / Fuentes, Patricio / Gloger, Sergio / Maccioni, Ricardo B

Journal of Alzheimer's disease : JAD

2021 Volume 81, Issue 3, Page(s) 1231–1241

Abstract: Background: Clinically-evaluated nutraceuticals are candidates for Alzheimer's disease (AD) prevention and treatment. Phase I studies showed biological safety of the nutraceutical BrainUp-10®, while a pilot trial demonstrated efficacy for treatment. ... ...

Abstract	Background: Clinically-evaluated nutraceuticals are candidates for Alzheimer's disease (AD) prevention and treatment. Phase I studies showed biological safety of the nutraceutical BrainUp-10®, while a pilot trial demonstrated efficacy for treatment. Cell studies demonstrated neuroprotection. BrainUp-10® blocks tau self-assembly. Apathy is the most common of behavioral alterations. Objective: The aim was to explore efficacy of BrainUp-10® in mitigating cognitive and behavioral symptoms and in providing life quality, in a cohort of Chilean patients with mild to moderate AD. Methods: The was a multicenter, randomized, double blind, placebo-controlled phase II clinical study in mild to moderate AD patients treated with BrainUp-10® daily, while controls received a placebo. Primary endpoint was Apathy (AES scale), while secondary endpoints included Mini-Mental State Examination (MMSE), Trail Making Test (TMT A and TMT B), and Neuropsychiatry Index (NPI). AD blood biomarkers were analyzed. Laboratory tests were applied to all subjects. Results: 82 patients were enrolled. The MMSE score improved significantly at week 24 compared to baseline with tendency to increase, which met the pre-defined superiority criteria. NPI scores improved, the same for caregiver distress at 12th week (p = 0.0557), and the alimentary response (p = 0.0333). Apathy tests showed a statistically significant decrease in group treated with BrainUp-10®, with p = 0.0321 at week 4 and p = 0.0480 at week 12 treatment. A marked decrease in homocysteine was shown with BrainUp-10® (p = 0.0222). Conclusion: Data show that BrainUp-10® produces a statistically significant improvement in apathy, ameliorating neuropsychiatric distress of patients. There were no compound-related adverse events. BrainUp-10® technology may enable patients to receive the benefits for their cognitive and behavioral problems.
MeSH term(s)	Aged ; Aged, 80 and over ; Alzheimer Disease/drug therapy ; Alzheimer Disease/psychology ; Cholinesterase Inhibitors/therapeutic use ; Dietary Supplements/adverse effects ; Double-Blind Method ; Female ; Humans ; Male ; Middle Aged ; Treatment Outcome
Chemical Substances	Cholinesterase Inhibitors
Language	English
Publishing date	2021-05-26
Publishing country	Netherlands
Document type	Journal Article ; Multicenter Study ; Randomized Controlled Trial ; Research Support, Non-U.S. Gov't
ZDB-ID	1440127-7
ISSN	1875-8908 ; 1387-2877
ISSN (online)	1875-8908
ISSN	1387-2877
DOI	10.3233/JAD-201501
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Article ; Online: Biomarkers for Alzheimer's Disease.

Guzman-Martinez, Leonardo / Maccioni, Ricardo B / Farías, Gonzalo A / Fuentes, Patricio / Navarrete, Leonardo P

Current Alzheimer research

2019 Volume 16, Issue 6, Page(s) 518–528

Abstract: Alzheimer´s disease (AD) and related forms of dementia are increasingly affecting the aging population throughout the world, at an alarming rate. The World Alzheimer´s Report indicates a prevalence of 46.8 million people affected by AD worldwide. As ... ...

Abstract	Alzheimer´s disease (AD) and related forms of dementia are increasingly affecting the aging population throughout the world, at an alarming rate. The World Alzheimer´s Report indicates a prevalence of 46.8 million people affected by AD worldwide. As population ages, this number is projected to triple by 2050 unless effective interventions are developed and implemented. Urgent efforts are required for an early detection of this disease. The ultimate goal is the identification of viable targets for the development of molecular markers and validation of their use for early diagnosis of AD that may improve treatment and the disease outcome in patients. The diagnosis of AD has been difficult to resolve since approaches for early and accurate detection and follow-up of AD patients at the clinical level have been reported only recently. Some proposed AD biomarkers include the detection of pathophysiological processes in the brain in vivo with new imaging techniques and novel PET ligands, and the determination of pathogenic proteins in cerebrospinal fluid showing anomalous levels of hyperphosphorylated tau and low Aβ peptide. These biomarkers have been increasingly accepted by AD diagnostic criteria and are important tools for the design of clinical trials, but difficulties in accessibility to costly and invasive procedures have not been completely addressed in clinical settings. New biomarkers are currently being developed to allow determinations of multiple pathological processes including neuroinflammation, synaptic dysfunction, metabolic impairment, protein aggregation and neurodegeneration. Highly specific and sensitive blood biomarkers, using less-invasive procedures to detect AD, are derived from the discoveries of peripheric tau oligomers and amyloid variants in human plasma and platelets. We have also developed a blood tau biomarker that correlates with a cognitive decline and also with neuroimaging determinations of brain atrophy.
MeSH term(s)	Alzheimer Disease/diagnosis ; Biomarkers/analysis ; Humans
Chemical Substances	Biomarkers
Language	English
Publishing date	2019-05-16
Publishing country	United Arab Emirates
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Review
ZDB-ID	2205170-3
ISSN	1875-5828 ; 1567-2050
ISSN (online)	1875-5828
ISSN	1567-2050
DOI	10.2174/1567205016666190517121140
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Article ; Online: The Republic of Chile: an upper middle-income country at the crossroads of economic development and aging.

Gitlin, Laura N / Fuentes, Patricio

The Gerontologist

2012 Volume 52, Issue 3, Page(s) 297–305

Abstract: Chile is a developing country with a rapidly expanding economy and concomitant social and cultural changes. It is expected to become a developed country within 10 years. Chile is also characterized as being in an advanced demographic transition. Unique ... ...

Abstract	Chile is a developing country with a rapidly expanding economy and concomitant social and cultural changes. It is expected to become a developed country within 10 years. Chile is also characterized as being in an advanced demographic transition. Unique challenges are posed by the intersection of rapid economic development and an aging population, making Chile an intriguing case study for examining the impact of these societal-level trends on the aging experience. This paper highlights essential characteristics of this country for understanding its emerging aging society. It reveals that there is a fundamental lack of adequate and depthful epidemiologic and country-specific research from which to fully understand the aging experience and guide new policies in support of health and well-being.
MeSH term(s)	Adolescent ; Adult ; Age Distribution ; Aged ; Aged, 80 and over ; Aging ; Child ; Child, Preschool ; Chile ; Demography ; Economic Development ; Health Care Reform ; Health Status Indicators ; Humans ; Income ; Infant ; Infant, Newborn ; Middle Aged ; Population Dynamics ; Public Policy ; Social Planning ; Socioeconomic Factors ; Young Adult
Language	English
Publishing date	2012-04-25
Publishing country	United States
Document type	Journal Article
ZDB-ID	216760-8
ISSN	1758-5341 ; 0016-9013
ISSN (online)	1758-5341
ISSN	0016-9013
DOI	10.1093/geront/gns054
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Book ; Online: Multi-qubit time-varying quantum channels for NISQ-era superconducting quantum processors

Martinez, Josu Etxezarreta / Fuentes, Patricio / iOlius, Antonio deMarti / Garcia-Frías, Javier / Fonollosa, Javier Rodríguez / Crespo, Pedro M.

2022

Abstract: Recent experimental studies have shown that the relaxation time ($T_1$) and the dephasing time ($T_2$) of superconducting qubits fluctuate considerably over time. To appropriately consider this time-varying nature of the $T_1$ and $T_2$ parameters, a new ...

Abstract	Recent experimental studies have shown that the relaxation time ($T_1$) and the dephasing time ($T_2$) of superconducting qubits fluctuate considerably over time. To appropriately consider this time-varying nature of the $T_1$ and $T_2$ parameters, a new class of quantum channels, known as Time-Varying Quantum Channels (TVQCs), has been proposed. In previous works, realizations of multi-qubit TVQCs have been assumed to be equal for all the qubits of an error correction block, implying that the random variables that describe the fluctuations of $T_1$ and $T_2$ are block-to-block uncorrelated, but qubit-wise perfectly correlated for the same block. Physically, the fluctuations of these decoherence parameters are explained by the incoherent coupling of the qubits with unstable near-resonant two-level-systems (TLS), which indicates that such variations may be local to each of the qubits of the system. In this article, we perform a correlation analysis of the fluctuations of the relaxation times of multi-qubit quantum processors ibmq\_quito, ibmq\_belem, ibmq\_lima, ibmq\_santiago and ibmq\_bogota. Our results show that it is reasonable to assume that the fluctuations of the relaxation and dephasing times of superconducting qubits are local to each of the qubits of the system. Based on these results, we discuss the multi-qubit TVQCs when the fluctuations of the decoherence parameters for an error correction block are qubit-wise uncorrelated (as well as from block-to-block), a scenario we have named the Fast Time-Varying Quantum Channel (FTVQC). Furthermore, we lower bound the quantum capacity of general FTVQCs based on a quantity we refer to as the ergodic quantum capacity. Finally, we use numerical simulations to study the performance of quantum error correction codes (QECC) when they operate over FTVQCs. Comment: 21 pages
Keywords	Quantum Physics
Subject code	612
Publishing date	2022-07-14
Publishing country	us
Document type	Book ; Online
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