Unconditional Security of Three State Quantum Key Distribution Protocols

Quantum key distribution (QKD) protocols are cryptographic techniques with security based only on the laws of quantum mechanics. Two prominent QKD schemes are the BB84 and B92 protocols that use four and two quantum states, respectively. In 2000, Phoenix et al. proposed a new family of three state protocols that offers advantages over the previous schemes. Until now, an error rate threshold for security of the symmetric trine spherical code QKD protocol has only been shown for the trivial intercept/resend eavesdropping strategy. In this paper, we prove the unconditional security of the trine spherical code QKD protocol, demonstrating its security up to a bit error rate of 9.81%. We also discuss on how this proof applies to a version of the trine spherical code QKD protocol where the error rate is evaluated from the number of inconclusive events.Comment: 4 pages, published versio

Robust Quantum Communication Using A Polarization-Entangled Photon Pair

Noise and imperfection of realistic devices are major obstacles for implementing quantum cryptography. In particular birefringence in optical fibers leads to decoherence of qubits encoded in polarization of photon. We show how to overcome this problem by doing single qubit quantum communication without a shared spatial reference frame and precise timing. Quantum information will be encoded in pair of photons using ``tag'' operations which corresponds to the time delay of one of the polarization modes. This method is robust against the phase instability of the interferometers despite the use of time-bins. Moreover synchronized clocks are not required in the ideal situation no photon loss case as they are only necessary to label the different encoded qubits.Comment: 4 pages, 2 figure

Novel Blood Biomarkers for an Earlier Diagnosis of Alzheimer’s Disease: A Literature Review

Alzheimer’s disease is a neurodegenerative condition associated with neurofibrillary tangles and cortical deposition of amyloid plaques. Clinical presentation of the disease involves manifestations such as memory loss, cognitive decline and dementia with some of the earliest reported deficits being episodic memory impairment and olfactory dysfunction. Current diagnostic approaches rely on autopsy characterization of gross brain pathology, or brain imaging of biomarkers late in the disease course. The aim of this literature review is to identify and compare novel blood-based biomarkers with the potential of making an earlier clinical diagnosis of Alzheimer’s disease. Utilizing such techniques may allow for earlier therapeutic intervention, reduction of disability and enhancement of patients’ quality of life. Literature review and analysis was performed by screening the PubMed database for relevant studies between July 1, 2014 and December 31, 2019. Sixteen studies were reviewed with biomarker candidates categorized under microRNAs (miRNAs), auto-antibodies, other blood-based proteins or circulating nucleic acids. Three biomarker candidates – serum neurofilament light chain, plasma ?-secretase 1 activity and a panel of three miRNAs (miR-135a/193b/384) – reported statistically significant differences in testing between patients and controls, with high discriminative potential and high statistical power. In conclusion, certain blood biomarkers have shown promising results with high sensitivity and specificity, high discriminative potential for Alzheimer’s disease early in its progression, and statistically significant results in larger study samples. Utilization of such diagnostic biomarkers could increase the efficacy of making an earlier clinical diagnosis of Alzheimer’s disease

FKBP5 Gene Variants as Predictors for Antidepressant Response in Individuals with Major Depressive Disorder Who Have Experienced Childhood Trauma. A Systematic Review

FKBP5 gene variants may predict antidepressant treatment response in individuals with Major Depressive Disorder. PubMed and Web of Science were searched systematically for articles studying individuals who had received a diagnosis of Major Depressive Disorder (MDD) and were given antidepressant treatment. Inclusion criteria were studies that researched FKBP5 and its variants and focused on antidepressant treatment response. Previous studies support a potential underlying epigenetic mechanism, demethylation at FKBP5 polymorphisms (rs1360780, rs3800373, rs9470080, and rs4713916) after experiencing childhood trauma, leading to increased hypothalamic-pituitary-adrenal (HPA) axis sensitivity and a propensity for the development of MDD. These polymorphisms informed the review, but additional polymorphisms (rs9380514, rs352428) were also considered. Studies conducted prior to 2008, reviews, meta-analyses, editorials, and non-research-based articles were excluded. Studies examined in this article suggest FKBP5 polymorphism rs4713916 and FKBP5 RNA levels may be associated with antidepressant response. Variants rs1360780, rs3800373, and rs9470080 were associated with both positive response and non-response or lack of remission. Variants rs9380514, rs352428, and rs936882 were associated with poor response to antidepressant treatment or non-remission. Further insights into the role FKBP5 plays in development and antidepressant treatment response may be aided by future studies focused on individuals who previously experienced childhood trauma and later developed MDD

Self-Reported Energy Intake and Energy Expenditure in Elderly Women

The elderly are a growing population; however, limited information concerning energy requirements of the elderly is available. Dietary intake data have been collected in research and clinical settings to determine the intakes of energy and nutrients, but the accuracy of dietary intake data has been difficult to verify. Studies using doubly labeled water have suggested that dietary energy intake is underreported by obese subjects (1), adolescents (2), and athletes (3). Diet records were collected for 6 to 14 days in these studies (1), (2), (3). Elderly subjects have also underreported energy intake compared with total energy expenditure (TEE), either measured (4), (5), (6) or predicted (7). However, these studies only collected dietary data for 3 or 4 days, while energy expenditure was measured for 10 to 14 days using doubly labeled water. It is generally accepted that a major source of random variation in dietary energy can be ascribed to a person\u27s day-to-day variation in energy consumption, which averages 20% to 30% (8). This random variation decreases as the square root of the number of study days increases, such that it is approximately 10% for a 7-day record (9). Thus, some of the variability in self-reported energy intake may be attributable to the limited number of observations taken in previous studies of elderly women. To our knowledge, a comparison of TEE using doubly labeled water and concurrent diet records for a full week for elderly women has not been reported previously. The purpose of our study was to determine whether a complete recording of dietary intake would improve the accuracy of and reduce the individual variation in self-reported dietary energy intake compared with energy expenditure measurements using doubly labeled water

Higher Security Thresholds for Quantum Key Distribution by Improved Analysis of Dark Counts

We discuss the potential of quantum key distribution (QKD) for long distance communication by proposing a new analysis of the errors caused by dark counts. We give sufficient conditions for a considerable improvement of the key generation rates and the security thresholds of well-known QKD protocols such as Bennett-Brassard 1984, Phoenix-Barnett-Chefles 2000, and the six-state protocol. This analysis is applicable to other QKD protocols like Bennett 1992. We examine two scenarios: a sender using a perfect single-photon source and a sender using a Poissonian source.Comment: 6 pages, 2 figures, v2: We obtained better results by using reverse reconciliation as suggested by Nicolas Gisi