Phase-coherent lightwave communications with frequency combs

Fiber-optical networks are a crucial telecommunication infrastructure in society. Wavelength division multiplexing allows for transmitting parallel data streams over the fiber bandwidth, and coherent detection enables the use of sophisticated modulation formats and electronic compensation of signal impairments. In the future, optical frequency combs may replace multiple lasers used for the different wavelength channels. We demonstrate two novel signal processing schemes that take advantage of the broadband phase coherence of optical frequency combs. This approach allows for a more efficient estimation and compensation of optical phase noise in coherent communication systems, which can significantly simplify the signal processing or increase the transmission performance. With further advances in space division multiplexing and chip-scale frequency comb sources, these findings pave the way for compact energy-efficient optical transceivers.Comment: 17 pages, 9 figure

Durability of antireflective SiO2 coatings with closed pore structure

The use of antireflective coatings to increase the transmittance of the cover glass is a central aspect of achieving high efficiencies for solar collectors and photovoltaics alike. Considering an expected lifetime of 20-30 years for solar energy installations, the durability of the antireflective surfaces is essential. Here, a novel antireflective SiO2 coating with a hexagonally ordered closed pore structure, produced with an aerosol-based sol-gel method is benchmarked against two commercial coatings; produced with acid etching and sol-gel roll coating. The optical and mechanical properties together with contact angle characteristics were evaluated before and after various durability tests, including climate chamber tests, outdoor exposure, and abrasion. Compared to the commercial antireflective coatings with open pore structures, the novel coating performed in parity, or better, in all tests. Based on the results of humidity freeze and industrial climate chamber tests, it appears that the coating with closed pore structure has a better ability to prevent water adsorption. Additionally, the closed pore structure of the coating seems to minimize the accumulation of dirt and deposits. The abrasion and cleanability test further confirm the advantages of a closed pore structure, showcasing the coating's mechanical durability. While the coatings exhibit similar hardness and reduced elastic modulus, the closed pore coating proves to be even harder after undergoing the industrial climate chamber test, but also slightly more brittle, as indicated by the probability of crack initiation. In summary the closed pore structure is well suited for tempered and arid climates, making it a truly competitive alternative to existing antireflective coatings

Electroconvulsive Therapy in Depression: Improvement in Quality of Life Depending on Age and Sex

Objectives It is uncertain if there are variations in the improvement of quality in life between sexes and age groups after electroconvulsive therapy (ECT). The aim of this study was to investigate how health-related quality of life changed after treatment and to examine differences in the results between sex and age groups. Methods This register-based study used data from the Swedish national quality register for ECT. The study population was patients diagnosed with depression who had received ECT. Health-related quality of life was quantified using the 3-level version the EuroQol 5-dimensional questionnaire (EQ-5D 3 L). Analysis of variance was used to compare change in EQ-5D score from pretreatment to posttreatment between sex and age groups. Results There was a statistically significant improvement in EQ-5D index score and EQ visual analog scale (VAS) score in all patient groups after ECT. The mean improvement in EQ-5D index score and EQ-VAS score ranged from 0.31 to 0.46 and 28.29 to 39.79, respectively. Elderly patients had greater improvement in EQ-5D index score and EQ-VAS score than younger patients. There was no significant difference in improvement between the sexes. The mean improvement in EQ-5D index score was 0.40 for male patients and 0.41 for female patients. Conclusions Electroconvulsive therapy had a considerable effect on health-related quality of life in patients with depression of both sexes and all age groups. The improvement was greatest in elderly patients, who more often had psychotic features. More studies are needed to investigate the long-term effects of ECT and to further explain the varying treatment results between elderly and younger patients.publishedVersio

Pain and the biochemistry of fibromyalgia: patterns of peripheral cytokines and chemokines contribute to the differentiation between fibromyalgia and controls and are associated with pain, fat infiltration and content

ObjectivesThis explorative study analyses interrelationships between peripheral compounds in saliva, plasma, and muscles together with body composition variables in healthy subjects and in fibromyalgia patients (FM). There is a need to better understand the extent cytokines and chemokines are associated with body composition and which cytokines and chemokines differentiate FM from healthy controls.MethodsHere, 32 female FM patients and 30 age-matched female healthy controls underwent a clinical examination that included blood sample, saliva samples, and pain threshold tests. In addition, the subjects completed a health questionnaire. From these blood and saliva samples, a panel of 68 mainly cytokines and chemokines were determined. Microdialysis of trapezius and erector spinae muscles, phosphorus-31 magnetic resonance spectroscopy of erector spinae muscle, and whole-body magnetic resonance imaging for determination of body composition (BC)—i.e., muscle volume, fat content and infiltration—were also performed.ResultsAfter standardizing BC measurements to remove the confounding effect of Body Mass Index, fat infiltration and content are generally increased, and fat-free muscle volume is decreased in FM. Mainly saliva proteins differentiated FM from controls. When including all investigated compounds and BC variables, fat infiltration and content variables were most important, followed by muscle compounds and cytokines and chemokines from saliva and plasma. Various plasma proteins correlated positively with pain intensity in FM and negatively with pain thresholds in all subjects taken together. A mix of increased plasma cytokines and chemokines correlated with an index covering fat infiltration and content in different tissues. When muscle compounds were included in the analysis, several of these were identified as the most important regressors, although many plasma and saliva proteins remained significant.DiscussionPeripheral factors were important for group differentiation between FM and controls. In saliva (but not plasma), cytokines and chemokines were significantly associated with group membership as saliva compounds were increased in FM. The importance of peripheral factors for group differentiation increased when muscle compounds and body composition variables were also included. Plasma proteins were important for pain intensity and sensitivity. Cytokines and chemokines mainly from plasma were also significantly and positively associated with a fat infiltration and content index.ConclusionOur findings of associations between cytokines and chemokines and fat infiltration and content in different tissues confirm that inflammation and immune factors are secreted from adipose tissue. FM is clearly characterized by complex interactions between peripheral tissues and the peripheral and central nervous systems, including nociceptive, immune, and neuroendocrine processes

Visual assessment of biliary excretion of Gd-EOB-DTPA in patients with suspected diffuse liver disease – A biopsy-verified prospective study

AbstractObjectivesTo qualitatively evaluate late dynamic contrast phases, 10, 20 and 30min, after administration of Gd-EOB-DTPA with regard to biliary excretion in patients presenting with elevated liver enzymes without clinical signs of cirrhosis or hepatic decompensation and to compare the visual assessment of contrast agent excretion with histo-pathological fibrosis stage, contrast uptake parameters and blood tests.Methods29 patients were prospectively examined using 1.5T MRI. The visually assessed presence or absence of contrast agent for each of five anatomical regions in randomly reviewed time-series was summarized on a four grade scale for each patient. The scores, including a total visual score, were related to the histo-pathological findings, the quantitative contrast agent uptake parameters, expressed as KHep or LSC_N, and blood tests.ResultsNo relationship between the fibrosis grade or contrast uptake parameters could be established. A negative correlation between the visual assessment and alkaline phosphatase (ALP) was found. Comparing a sub-group of cholestatic patients with fibrosis score and Gd-EOB-DTPA dynamic parameters did not add any additional significant correlation.ConclusionsNo correlation between visually assessed biliary excretion of Gd-EOB-DTPA and histo-pathological or contrast uptake parameters was found. A negative correlation between the visual assessment and alkaline phosphatase (ALP) was found

Laser Frequency Combs for Coherent Optical Communications

Laser frequency combs with repetition rates on the order of 10 GHz and higher can he used as multi-carrier sources in wavelength-division multiplexing (WDM). They allow replacing tens of tunable continuous-wave lasers by a single laser source. In addition, the comb\u27s line spacing stability and broadband phase coherence enable signal processing beyond what is possible with an array of independent lasers. Modern WDM systems operate with advanced modulation formats and coherent receivers. This introduces stringent requirements in terms of signal-to-noise ratio, power per line, and optical linewidth which can be challenging to attain for frequency comb sources. Here, we set quantitative benchmarks for these characteristics and discuss tradeoffs in terms of transmission reach and achievable data rates. We also highlight recent achievements for comb-based superchannels, including >10 Tb/s transmission with extremely high spectral efficiency, and the possibility to significantly simplify the coherent receiver by realizing joint digital signal processing. We finally discuss advances with microresonator frequency combs and compare their performance in terms of flatness and conversion efficiency against state-of-the-art electro-optic frequency comb generators. This contribution provides guidelines for developing frequency comb sources in coherent fiber-optic communication systems

Clinical and societal burden of incident major depressive disorder : A population-wide cohort study in Stockholm

Objective Major depressive disorder (MDD) is a highly prevalent condition and a significant contributor to global disability. The vast majority of MDD is handled by primary care, but most real-life studies on MDD only include data from secondary care. The aim of this study was therefore to estimate the total clinical and societal burden of incident MDD including data from all healthcare levels in a large well-defined western European healthcare region. Methods Population-wide observational study included healthcare data from Region Stockholm, Sweden's largest region with approximately 2.4 million inhabitants. All patients in Region Stockholm having their first unipolar MDD episode between January 1, 2012, and December 31, 2018, were included. The sample also included matched study population controls. Outcomes were psychiatric and non-psychiatric comorbid conditions, antidepressant therapy use, healthcare resource utilization, work loss, and all-cause mortality. Results In the study period, 137,822 patients in Region Stockholm were diagnosed with their first unipolar MDD episode. Compared with matched controls, MDD patients had a higher burden of non-psychiatric and psychiatric comorbid conditions, 3.2 times higher outpatient healthcare resource utilization and 8.6 times more work loss. MDD was also associated with a doubled all-cause mortality compared with matched controls (HR: 2.2 [95% CI: 2.0-2.4]). Conclusions The high mortality, morbidity, healthcare resource utilization, and work loss found in this study confirms that MDD is associated with individual suffering and low functioning leading to substantial costs for patients and society. These findings should motivate additional efforts in improving outcomes for MDD patients.Peer reviewe

Validity of diagnoses, treatment dates, and rating scales in the Swedish national quality register for electroconvulsive therapy

Background The Swedish national quality register for electroconvulsive therapy (Q-ECT) contains data on patients receiving treatment with electroconvulsive therapy (ECT) in Sweden. Aim This study determined the validity of diagnoses, treatment dates, and rating scales in the Q-ECT by investigating the degree of accordance between data from the Q-ECT and patient records. Materials and methods From January 2016 to December 2017, 200 treatment series were randomly selected from the Q-ECT. The corresponding patient records were requested from the treating hospitals. Data on the indicative diagnosis, dates for the first and the last ECT session, and rating scales were compared between the Q-ECT and patient records using (i) a strict and (ii) a liberal method of assessment. Using the liberal method, each variable was assessed as accordant if it belonged to the same diagnosis group, or if the dates differed by less than 1 week, or ratings differed by only 1 point on the Clinical Global Impression Scale (CGI- S), or no more than 3 points on the Montgomery Åsberg Depression Rating Scale between the Q-ECT and the patient record. Results A total of 179 patient records were received. The strict method of assessment showed an accordance of 89% or higher for all studied variables. The liberal method showed an accordance of 95% or higher. Conclusions We conclude that data on the studied variables in the Q-ECT have high validity. However, limited use of some rating scales makes the results uncertain. Measures can be taken to further improve the data quality.publishedVersio

Associations between cognition and serotonin receptor 1B binding in patients with major depressive disorder : a pilot study

The neurotransmitter serotonin has been widely implicated in the pathophysiology of major depressive disorder (MDD). In animal studies and human neuroimaging studies, involvement of the serotonin receptor 1B (5-HT1BR) in MDD and memory performance has been reported. However, the role of the 5-HT1BR in cognitive functions affected in MDD remains to be clarified. Ten patients with MDD diagnosis were examined with positron emission tomography (PET) and a battery of cognitive tests before and after Internet-based Cognitive Behavioral Therapy (ICBT). The results were compared to ten matched control subjects in order to investigate putative changes in 5-HT1BR availability and cognitive performance. Patients treated with ICBT showed statistically significant improvement relative to baseline in Verbal fluency, both letter and category production. Significant correlations were found between improvement in letter production and changes in 5-HT1BR availability in ventral striatum, between category production and amygdala, as well as between the improvement in Trailmaking test B and change in 5-HT1BR binding in dorsal brainstem, in amygdala and in hippocampus. The results suggest an association between 5-HT1BR binding and improvement in cognitive functioning. Replications in larger-scale studies are required to confirm these findings.Swedish Research Council (523-2013-2982)Birgitta and Sten WesterbergSwedish Society of MedicineStiftelsen Söderström-Königska sjukhemmetStockholm County CouncilThe Stockholm Centre for Psychiatric ResearchKarolinska InstitutetAccepte

Frequency Comb-Based WDM Transmission Systems Enabling Joint Signal Processing

We review the use of optical frequency combs in wavelength-division multiplexed (WDM) fiber optic communication systems. In particular, we focus on the unique possibilities that are opened up by the stability of the comb-line spacing and the phase coherence between the lines. We give an overview of different techniques for the generation of optical frequency combs and review their use in WDM systems. We discuss the benefits of the stable line spacing of frequency combs for creating densely-packed optical superchannels with high spectral efficiency. Additionally, we discuss practical considerations when implementing frequency-comb-based transmitters. Furthermore, we describe several techniques for comb-based superchannel receivers that enables the phase coherence between the lines to be used to simplify or increase the performance of the digital carrier recovery. The first set of receiver techniques is based on comb-regeneration from optical pilot tones, enabling low-overhead self-homodyne detection. The second set of techniques takes advantage of the phase coherence by sharing phase information between the channels through joint digital signal processing (DSP) schemes. This enables a lower DSP complexity or a higher phase-noise tolerance