Search

Periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis syndrome (PFAPA) are the most common autoinflammatory syndromes in children. This study aimed to evaluate the clinical and laboratory parameters that may predict colchicine responsiveness.This retrospective, multicenter, cross-sectional study involved nine pediatric rheumatology centers from our country., The patients diagnosed with PFAPA were compared on the basis of their responses to colchicine. In the 806 (42.3% female 57.7% male) patients, the most common clinical findings were fever (100%), exudative tonsillitis (86.5%), pharyngitis (80.9%), and aphthous stomatitis (50.5%). The mean attack frequency was 13.5 ± 6.8 attacks per year lasting for a mean of 3.9 ± 1.1 days. Colchicine treatment was attempted in 519 (64.4%) patients, with 419 (80.7%) showing a favorable response. In patients who underwent MEFV gene analysis (70.8%), the most common variant was M694V heterozygous (16.8%). The presence of pharyngitis (p = 0.03, 95% CI 0.885 to 0.994), the presence of arthralgia (p = 0.04, 95% CI 0.169 to 0.958), and having more frequent attacks (p = 0.001, 95% CI 0.028 to 0.748) were found to be associated with colchicine unresponsiveness, whereas the carriage of the M694V variant (p = 0.001, 95% CI 0.065 to 0.242) was associated with colchicine responsiveness. Conclusion: This study identified the presence of pharyngitis, arthralgia, and increased attack frequency in patients with PFAPA as factors predicting colchicine unresponsiveness, whereas the carriage of the M694V variant emerged as a predictor of colchicine responsiveness. Predicting colchicine response at disease onset may facilitate a more effective management of PFAPA. What is Known: • Colchicine treatment can be used in the prophylaxis of PFAPA disease. • Having the MEFV variant is the most commonly known factor in predicting response to colchicine. What is New: • The presence of pharyngitis or arthralgia, and more frequent attacks in PFAPA disease were found to be independently associated with colchicine unresponsiveness. • Carrying the M694V variant was identified as the sole factor predicting colchicine responsiveness. [ABSTRACT FROM AUTHOR]

Classical attacks of familial Mediterranean fever (FMF) are often accompanied by fever, but some of the patients have attacks without fever. This study aimed to compare the characteristics of FMF patients with and without fever during their attacks and draw attention to the different clinical presentations of FMF in children. Medical files of patients aged 0–18 years who were followed up with the diagnosis of FMF in two reference pediatric rheumatology centers were reviewed retrospectively. The patients were divided into two groups: children who had had no fever in any of their attacks were assigned as group 1, and those who had fever during their attacks were classified as group 2. Out of 2003 patients evaluated, 191 (9.53%) patients had attacks not accompanied by fever and their median age at onset of symptoms (7.0 vs. 4.0 years, p < 0.001) and the median age at diagnosis (8.6 vs. 6.0 years, p < 0.001) were significantly higher; however, group 2 had a delay in diagnosis. The annual number of attacks and abdominal attacks were more common in group 2; arthritis, arthralgia, erysipelas-like rash, exercise-induced leg pain, and myalgia were more common in group 1. Conclusion: The data from the assessment of children with FMF attacks not accompanied with fever were presented for the first time. Children with late age onset of FMF and dominance of musculoskeletal features may display attacks not accompanied with fever. What is Known: • Familial Mediterranean fever (FMF) is the most common inherited auto-inflammatory disease, characterized by recurrent attacks of fever, serositis, and musculoskeletal symptoms. • Although fever is the most common symptom, few studies have reported attacks without fever. What is New: • The aim of this study was to identify patients with FMF but without fever during attacks and to demonstrate their distinctive presentations. • We found that 7% of our patients had afebrile attacks with predominant musculoskeletal symptoms and were diagnosed earlier than patients with febrile attacks, probably due to early referral to pediatric rheumatology clinics. [ABSTRACT FROM AUTHOR]

Pediatric mixed connective tissue disease (MCTD) is a subgroup of overlap syndromes. We aimed to compare the characteristics and outcomes in children with MCTD and other overlap syndromes. All MCTD patients met either Kasukawa or Alarcon-Segovia and Villareal criteria. The patients with other overlap syndromes had the features of ≥ 2 autoimmune rheumatic diseases but did not meet MCTD diagnostic criteria. Thirty MCTD (F/M = 28/2) and thirty (F/M = 29/1) overlap patients were included (disease onset < 18 years). The most prominent phenotype at disease onset and the last visit was systemic lupus erythematosus (SLE) in the MCTD group; juvenile idiopathic arthritis and dermatomyositis/polymyositis, respectively, in the overlap group. At the last visit, systemic sclerosis (SSc) phenotype was more frequent among MCTD than overlap patients (60% vs. 33.3%; p = 0.038). The frequency of the predominant SLE phenotype had decreased (60% to 36.7%), while predominant SSc phenotype had increased (13.3% to 33.3%) during follow-up in MCTD patients. Weight loss (36.7% vs. 13.3%), digital ulcers (20% vs. 0), swollen hands (60% vs. 20%), Raynaud phenomenon (86.7% vs. 46.7%), hematologic involvement (70% vs. 26.7%), and anti-Sm positivity (29% vs. 3.3%) were more common, while Gottron papules (16.7% vs. 40%) were less frequent among MCTD than overlap patients (p < 0.05). A higher percentage of overlap patients achieved complete remission than MCTD patients (51.7% vs. 24.1%; p = 0.047). The disease phenotype and outcome differ between pediatric MCTD and other overlap syndromes where MCTD may be regarded as a more severe disease. Analyzing these patients could pave the way for early and effective treatment. [ABSTRACT FROM AUTHOR]

To evaluate the safety profile of measles, mumps and rubella (MMR) booster in children diagnosed with rheumatic diseases receiving biological agents. The study included retrospective safety data of children administered MMR booster dose receiving biologics or biologics with methotrexate. The files of 182 patients were accessed from the pediatric rheumatology biological therapy archive, and the vaccination status of these children was obtained by accessing electronic records. Of 182 patients, 14 patients were vaccinated with MMR booster dose. Thirteen of the patients were followed up with a diagnosis of juvenile idiopathic arthritis and one with colchicine-resistant familial Mediterranean fever. None of the patients had disease exacerbation after vaccination, and three patients had mild side effects consisting of rash, angioedema, joint pain, and fatigue. Conclusion: This study supports the data regarding evidence of the safety of MMR booster dose administration in children with rheumatic diseases receiving bDMARDs. What is Known: • MMR booster is avoided in immunocompromised pediatric patients receiving bDMARDs except in specific conditions. What is New: • The MMR booster dose may be safe in children with PedRD receiving bDMARDs or bDMARDs with MTX. These bullets can be added to the manuscript. [ABSTRACT FROM AUTHOR]

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease manifesting with phenotypic heterogeneity. The phenotype–genotype correlation is not established clearly yet. Furthermore, some comorbidities such as vasculitis and inflammatory arthritis may accompany FMF. Herein, we aimed to define phenotype–genotype correlation and comorbid diseases of children with FMF. The medical records of 1687 children diagnosed and followed up as FMF were reviewed retrospectively. Disease severity was assessed by PRAS score. A total of 1687 children (841 girls, 846 boys) were involved in the study. The mean ± standard deviation of current age, age at symptom onset, and age at diagnosis were 13.1 ± 5.4, 5.4 ± 4, and 8 ± 4.2 years, respectively. Median (min–max) follow-up period was 3 (0.5–18) years. Among them, 118 (7%) patients had at least one concomitant disease and 72% of them were carrying at least one M694V mutation. Patients with a concomitant disease expressed a more severe course of disease when compared to ones without a concomitant disease (23.7% vs 8.8%, p < 0.001). Children carrying homozygous M694V mutation had significantly earlier age of disease onset and severe disease course (p < 0.001). Forty-four patients (2.6%) were colchicine resistant and most of them were carrying homozygous M694V mutation. Sixteen colchicine-resistant patients were treated with anakinra while 28 received canakinumab. Juvenile idiopathic arthritis (JIA) and immunoglobulin A vasculitis were the most commonly seen associated diseases and the patients with a concomitant disease demonstrated more severe course. This is the largest pediatric cohort studied and presented since now. We confirmed that carrying M694V mutation is associated both with a severe disease course and a predisposition to comorbidities. [ABSTRACT FROM AUTHOR]

Juvenile-onset systemic lupus erythematosus (jSLE) patients typically have a more severe disease course than adults with SLE. We aimed to assess the prevalence and disease course of jSLE patients carrying MEFV variants. MEFV variant analyses were performed in 44 jSLE patients and effect of these variants on disease severity and course was analyzed by SLEDAI score and SLICC/ACR index. Ten of the patients (22.7%) had a MEFV variant. The median (min–max) SLEDAI score and SLICC/ACR index were 2(0–13) and 0(0–3), respectively. Median age at disease onset, disease duration, SLICC/ACR indexes, SLEDAI scores, clinical and laboratory findings of the patients were comparable in carriers of variants and non-carriers. Nineteen patients (43.2%) had biopsy-proven lupus nephritis and four of these patients had MEFV variants. There was no significant difference between patients with and without MEFV carriers in terms of lupus nephritis. Even though not significant statistically, renal involvement was milder in MEFV carriers than non-carriers. The presence of MEFV variants does not increase the overall susceptibility to jSLE in our cohort, while larger number of patients is required to display the protective role of MEFV variants in jSLE. [ABSTRACT FROM AUTHOR]

The aim of the research was to further extend current knowledge of whether severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disease 2019 (COVID-19) entails a risk for children with various rheumatic diseases under immunosuppressive treatment. Telephone survey was administered by conducting interviews with the parents from May 1, 2020 to May 20, 2020. A message containing a link to the actual questionnaire was sent to their phones simultaneously. The medical records of the patients were reviewed for gathering information about demographic data, clinical follow-up, and treatments. Patients who were followed-up under immunosuppressive treatment (n = 439) were attempted to be contacted. The diagnostic distribution of patients (n = 414) eligible for the study was as follows: juvenile idiopathic arthritis (JIA) (n = 243, 58.7%), autoinflammatory diseases (n = 109, 26.3%), connective tissue diseases (n = 51, 12.3%), and vasculitis (n = 11, 2.7%). In the entire cohort, the mean age was 12 ± 4.7 years, and 54.1% (n = 224) were female. Nine patients have attended the hospital for COVID-19 evaluation, 6 of whom were in close contact with confirmed cases. One patient with seronegative polyarticular JIA, previously prescribed methotrexate and receiving leflunomide during pandemic was identified to be diagnosed with COVID-19. None, including the confirmed case, had any severe symptoms. More than half of the patients with household exposure did not require hospitalization as they were asymptomatic. Although circumstances such as compliance in social distancing policy, transmission patterns, attitude following contact may have influenced the results, immunosuppressive treatment does not seem to pose an additional risk in terms of COVID-19. [ABSTRACT FROM AUTHOR]

We investigate the effects of exchange and correlation on the quasiparticle properties such as the self-energy, the many-body effective mass and the renormalization constant in a two-dimensional system of ultracold dipolar fermions with dipole moments aligned in the perpendicular direction to the plane. We use the G0W approximation along with the generalized random phase approximation, where the many-body effects have been incorporated in the effective interaction W through the Hubbard local-field factor. The many-body effective mass and the renormalization constant are reduced with the increase of coupling strength. We also study the effect of dipole-dipole interaction on the single-particle spectral function of the two dimensional dipolar Fermi liquid. We observe composite hole-zero sound excitation which is a bound state of quasiparticles with the collective mode (i.e. zero-sound) at intermediate and high coupling constants. These composite excitations are undamped at small wave vectors. Due to repulsion between quasiparticle and composite excitation resonances, we find a gap-like feature between quasiparticle and composite excitation dispersions at long wavelengths. [ABSTRACT FROM AUTHOR]

Parenteral treatments (either subcutaneous or intravenous) are frequently used in rheumatology practice. In this study, drug side effects in patients who were followed up with a rheumatic disease and treated with parenteral administration methods were evaluated. The drug side effects in children who were followed up with a rheumatic disease and treated with parenteral treatments between 2010 and 2019 were recorded, retrospectively. All parenteral treatments are applied by a clinical nurse specialist (CNS) who is experienced in pediatric rheumatology for 10 years. Four hundred and thirteen patients were evaluated in this study. The mean age was 12.09 ± 5.05 years. Most of them were diagnosed with juvenile idiopathic arthritis (n = 317) and colchicine-resistant familial Mediterranean fever (n = 57). Among the patients, 287 was treated with methotrexate, 130 with etanercept, 90 with adalimumab, 71 with anakinra, 64 with canakinumab, 55 with tocilizumab, seven with rituximab, six with infliximab, and four with abatacept. Two of the patients had a history of drug allergy (ceftriaxone = 1, ranitidine = 1). The most common adverse reactions were as follows: nausea–vomiting in 52, rash in 11, itching in three, chest tightening in two, bruising in two, headache in two, and abdominal pain in one of the patients. Drug side effects were observed after an average of three (1–4) administrations. Antihistaminic and steroids (tocilizumab = 3, infliximab = 1, methotrexate = 1) were administered to five patients due to hypersensitivity reactions. Considering the possible side effects and preparation protocols of parenteral treatments, experienced physicians and nurses are required in the field. [ABSTRACT FROM AUTHOR]

Since the Syrian civil war in 2011, an estimated number of 3.6 million Syrian refugees crossed into Turkey, and almost half of them were children. The distribution of rheumatic diseases in Syrian refugee children is not known. The aim of this study was to describe the profile of rheumatic diseases in Syrian refugee children living in Turkey. The demographic data, clinical and laboratory findings, medications, complications and outcome results of Syrian refugee children who had visited Pediatric Rheumatology Departments of University of Health Science Kanuni Sultan Süleyman Research and Training Hospital, Ümraniye Research and Training Hospital, Şanlıurfa Research and Training Hospital, and Cengiz Gökçek Maternity and Gynecology Hospital between April 1, 2011, and September 1, 2019, were evaluated retrospectively. A total of 151 patients were included in the study. Among them, 51 patients had juvenile idiopathic arthritis (JIA), 49 had familial Mediterranean fever (FMF), 43 had vasculitis, and 8 had connective tissue diseases. Homozygous M694V mutation was the most common mutation among FMF patients. Oligoarticular JIA (41.2%) was the most frequent type of JIA, and enthesitis-related arthritis (ERA) (27.5%) was the second one. The frequency of systemic JIA was 11.8%. One patient with SLE died due to complicated meningitis. This is the first study evaluating the distribution of rheumatic diseases in Syrian refugee children. Clinical follow-up of rheumatologic diseases is difficult in Syrian refugees due to language barriers, social and cultural differences. Health care systems should be well organized to provide appropriate care to asylum seekers. [ABSTRACT FROM AUTHOR]

Objective: To describe the clinical features, genotype, and treatment approaches of patients with confirmed adenosine deaminase 2 (ADA2) deficiency with dissimilar phenotypes. Methods: A case series of five DADA2 patients from three families was presented. The clinical and laboratory data, treatment protocols, and outcome of the patients were recorded from the patients' medical charts. ADA2 gene was screened by next generation sequencing first and then verified by Sanger sequencing. Serum ADA2 enzyme activity was measured by modified spectrophotometric method. Results: The median (min–max) age at onset of symptoms and age at diagnosis were 11 (9–13.8) years and 15 (9–19) years, respectively. The median (min–max) follow-up period was 8 (6–45) months. There was consanguinity in two families (2/3). The main clinical manifestations are musculoskeletal (5/5), dermatological (4/5), and neurological (2/5). Homozygosity for the p.G47R mutation in ADA2 gene was detected in three patients. A homozygous mutation in ADA2 gene (c.650 T > A; p.Val217Asp) was detected in two siblings. Plasma ADA2 enzymatic activity was absent in all patients. Anti-tumor necrosis factor (TNF) therapy was commenced, and all patients became clinically inactive with normal acute-phase reactants. Conclusion: ADA2 mutations should be checked in patients with presence of inflammation and livedoid vasculitis when they have neurological findings, especially in the form of stroke; and a history suggesting for an inherited disease; or presence of resistance to conventional treatment. Besides, anti-TNF seems to be useful for treatment of DADA2. [ABSTRACT FROM AUTHOR]

To describe the demographic characteristics and clinical features of patients referred to a pediatric rheumatology outpatient clinic in Turkey and to compare the final diagnoses with the previous literature data. All new patients referred to pediatric rheumatology outpatient clinic of Kanuni Sultan Süleyman Research and Training Hospital between March 2018 and March 2019 were enrolled to the study. Demographic data, referral patterns, disease related features, physical examination findings and final diagnoses of new referrals were collected prospectively. A total of 2982 new referrals were evaluated in 1-year period. Among them 1561 (52%) had a diagnosis of a rheumatic disease. The frequencies of most common rheumatic diseases were; periodic fever syndromes (47.3%), juvenile idiopathic arthritis (18%) and vasculitis (14.4%), respectively. Non-rheumatic conditions were diagnosed in 1243 patients, among them orthopedic/mechanic problems (27.4%) were the most frequent ones followed by vitamin D deficiency (17.5%) and dermatological problems (9.8%). Patients with non-rheumatic conditions comprised a large part of the pediatric rheumatology outpatient clinic. National registries are required to establish the frequencies of pediatric rheumatic diseases in Turkey. [ABSTRACT FROM AUTHOR]

Until now, the diagnosis of familial Mediterranean fever (FMF) was based on validated subsets of clinical criteria, but recently new Eurofever/PRINTO classification criteria concerning genetic analyses were proposed. The study aimed to compare the performances of three validated diagnostic criteria (Tel-Hashomer, Livneh, pediatric criteria) and new Eurofever/PRINTO classification criteria. The medical charts of study and control groups were reviewed retrospectively. Patients were evaluated for three diagnostic criteria and new Eurofever/PRINTO classification criteria. Control group consists of patients with other autoinflammatory diseases. A total of 1291 patients were classified into three groups according to their mutations: group 1: 447 patients with homozygous mutations; group 2: 429 patients with compound heterozygous mutations; and group 3: 415 patients with one heterozygous mutation. Similar diagnostic utility was found according to Livneh criteria between groups. But, proportion of patients fulfilling Tel-Hashomer and pediatric criteria was higher in groups 1 and 2. According to Eurofever/PRINTO criteria, 98.2% of patients with homozygous mutations, 94.2% of patients with compound heterozygous mutations and 80.2% of patients with heterozygous mutations were classified as FMF. In control group, 99.2% of them fulfilled the Livneh criteria, 66.9% met the pediatric criteria and 0.8% satisfied the Tel-Hashomer criteria, while none of control patients met the Eurofever/PRINTO classification criteria. Performances of three validated diagnostic criteria and new Eurofever/PRINTO classification criteria for FMF were similar and provide high utility in diagnosing/classifying patients with homozygous and compound heterozygous mutations. However, both Eurofever/PRINTO classification criteria and Tel-Hashomer criteria had significantly lower performance in heterozygous patients. [ABSTRACT FROM AUTHOR]

Objective: To determine the capability of serum amyloid A (SAA) in differentiating attacks of familial Mediterranean fever (FMF) from acute febrile upper respiratory tract infections. Method: Children diagnosed with FMF during febrile attacks were recorded as the patient group. The control group consisted of children with febrile upper respiratory tract infections. Complete blood count, serum amyloid A (SAA), C-reactive protein (CRP), and erythrocyte sedimentation rate were recorded in both groups during febrile episodes. Results: The cohort consisted of 28 children with FMF attack and 28 previously healthy children with acute febrile infection. While CRP and SAA levels were elevated in both groups, elevations during FMF attacks were significantly higher in the FMF group than in the control group. Median CRP was 85 mg/L in the FMF attack group and was 36 mg/L in the control group (p = 0.001). Median SAA was 497.5 mg/L in the FMF attack group and was 131.5 mg/L in the control group (p < 0.001). Correlation analyses showed that SAA and CRP were positively correlated in the FMF attack group (r = 0.446, p = 0.01). The best cut-off value for SAA in differentiating FMF attack from an acute febrile infection was 111.5 mg/L (sensitivity 100%, specificity 65.1%, area under curve (AUC) = 0.78, confidence interval 0.66–0.90, p < 0.001). Conclusion: Serum amyloid A is a sensitive but not specific marker for demonstrating inflammation in FMF. SAA levels rise substantially in febrile upper respiratory tract infections. Key Points • SAA levels rise substantially in febrile upper respiratory tract infections. • SAA is a sensitive but not specific method for demonstrating inflammation. • SAA cut-off value for discriminating FMF attacks from febrile infection is 111.5 mg/L (sensitivity 100%, specificity 65.1%). [ABSTRACT FROM AUTHOR]

Juvenile idiopathic arthritis is the most common chronic rheumatic disease of childhood resulting in disability in untreated cases. Disease modifying anti-rheumatic drugs form the first-line treatment in JIA. However, the data about leflunomide (LFN) in treatment of JIA is limited. We reviewed the medical files of JIA patients who were followed-up regularly and had received LFN. A total of 38 patients were included to the study. Among them, 24 had oligoarticular JIA, eleven had polyarticular JIA, two had ERA and one had psoriatic arthritis. 36 were initially treated with methotrexate and two patients diagnosed with ERA were treated with sulfasalazine. Sulfasalazine treatment was switched to LFN due to inadequate response at the 3rd month of therapy. Methotrexate was ceased due to gastrointestinal intolerance in 36 patients. Of these 36 patients, 19 patients had either low disease activity (n = 13) or remission (n = 6). LFN was administered to 13 patients with low disease activity. During the follow-up of the six patients in remission, relapse ensued and LFN treatment was started. The remaining 17 patients had moderate (n = 10) or high (n = 7) disease activity requiring biologic agents. But due to inadequate response to biologic agents, LFN was added to the therapy. All of the patients were clinically inactive at the last visit. Only two adverse events resolving within 2 weeks were noted (Lymphopenia = 1, elevated liver enzymes = 1). LFN may be an alternative therapy in case of MTX intolerance or toxicity. [ABSTRACT FROM AUTHOR]

Most iron-based superconductors are characterized by the s± symmetry of their order parameter, and are expected to go through a transition to the s++ state if enough disorder is introduced. We previously reported the observation of this transition in Ba(Fe1−xRhx)2As2 through a study of the disorder dependence of the critical temperature and low-temperature London penetration depth. In this paper we report on the analysis of the electrodynamic response of the same sample across the transition and we identify peculiarities in the behaviour of the surface resistance and normal conductivity, that can be considered as traces of the transition itself. [ABSTRACT FROM AUTHOR]

Objectives: Henoch–Schönlein purpura (HSP) is the most common vasculitis of children. The aim of this study is to evaluate the demographic and clinic findings of patients with HSP and also to determine predictive factors for assessing the development of gastrointestinal system (GIS) and renal involvement. Methods: This study was performed prospectively among children with HSP who are under 18 years of age and being followed-up in the Pediatric Rheumatology Unit of Health Sciences University Kanuni Sultan Süleyman Training and Research Hospital between January 2016 and January 2018. Results: A total of 265 patients, 137 boys (51.7%) and 128 girls (48.3%), were involved to the study. The mean ± standard deviation of age at the diagnosis was 7.5 ± 3.2. The most common disease onset season was spring (31.7%). The rate of arthritis, GIS involvement, and renal involvement were 54%, 51.3%, and 29.1%, respectively. GIS bleeding was more frequent in males than females (p = 0.007). Boys over 7 years of age had significantly more common GIS bleeding (p = 0.04). Intussusception, relapse, and serious GIS involvement requiring hospitalization and steroid treatment were highly associated with severe renal involvement. Conclusions: We demonstrated that patients suffering intussusception, relapse, and serious GIS involvement or requiring hospitalization and steroid treatment had tendency to present with severe renal involvement. Therefore, these patients should be followed up carefully for not overlooking renal involvement of HSP. [ABSTRACT FROM AUTHOR]

The interplay between superconductivity and charge-density wave (CDW) in 2H-NbSe2 is not fully understood despite decades of study. Artificially introduced disorder can tip the delicate balance between two competing long-range orders, and reveal the underlying interactions that give rise to them. Here we introduce disorder by electron irradiation and measure in-plane resistivity, Hall resistivity, X-ray scattering, and London penetration depth. With increasing disorder, the superconducting transition temperature, Tc, varies non-monotonically, whereas the CDW transition temperature, TCDW, monotonically decreases and becomes unresolvable above a critical irradiation dose where Tc drops sharply. Our results imply that the CDW order initially competes with superconductivity, but eventually assists it. We argue that at the transition where the long-range CDW order disappears, the cooperation with superconductivity is dramatically suppressed. X-ray scattering and Hall resistivity measurements reveal that the short-range CDW survives above the transition. Superconductivity persists to much higher dose levels, consistent with fully gapped superconductivity and moderate interband pairing. [ABSTRACT FROM AUTHOR]

The iron-based high temperature superconductors exhibit a rich phase diagram reflecting a complex interplay between spin, lattice, and orbital degrees of freedom. The nematic state observed in these compounds epitomizes this complexity, by entangling a real-space anisotropy in the spin fluctuation spectrum with ferro-orbital order and an orthorhombic lattice distortion. A subtle and less-explored facet of the interplay between these degrees of freedom arises from the sizable spin-orbit coupling present in these systems, which translates anisotropies in real space into anisotropies in spin space. We present nuclear magnetic resonance studies, which reveal that the magnetic fluctuation spectrum in the paramagnetic phase of BaFe2As2 acquires an anisotropic response in spin-space upon application of a tetragonal symmetry-breaking strain field. Our results unveil an internal spin structure of the nematic order parameter, indicating that electronic nematic materials may offer a route to magneto-mechanical control. [ABSTRACT FROM AUTHOR]

We consider a two-dimensional system of ultracold dipolar fermions with dipole moments aligned in the perpendicular direction. We use the static structure factor information from Fermi-Hypernetted-Chain calculations to obtain the effective many-body dipole-dipole interaction and calculate the many-body effective mass of the system within the $$G_{0}W$$ approximation to the self-energy. A large cancellation between different contributions to the self-energy results in a weak dependence of the effective mass on the interaction strength over a large range of coupling constants. [ABSTRACT FROM AUTHOR]

We have read the letter "How to define disease severity accurately in patients with familial Mediterranean fever" [[1]] with great interest and we appreciate for giving us the opportunity to explain the poorly understood parts of our work. Familial Mediterranean fever (FMF) is the most common monogenic disease that accounts for almost half of the referrals to pediatric rheumatology clinics especially in the Mediterranean region [[2]]. [Extracted from the article]

We consider the collective modes of a bilayer dipolar Fermi system in which the particles interact via long range (∼1/ r) interaction. Assuming that each layer has a background flow which varies little and that the dynamics of the superfluid near T=0 is the same as that of a normal fluid, we obtain the dispersion relations for the collective modes in the presence of background flow. Decomposing the background flow into two parts, the center-of-mass flow and counterflow, we focus on the properties of the counterflow. We first find an estimate of the change in the zero-point energy ΔE due to counterflow for a unit area of bilayer. Combining this with the free energy F of the system and taking the partial derivatives with respect to background velocities in the layers, we determine the current densities which reveal the fact that current in one layer does not only depend on the velocity in the same layer but also on the velocity of the other layer. This is the drag effect and we calculate the drag coefficient. [ABSTRACT FROM AUTHOR]

We develop the formalism for BCS-BEC crossover in the presence of weak random impurity and calculate the effect of the random potentials on the basic mean-field quantities. The disorder has been included through the Nozières and Schmitt-Rink theory of superconducting fluctuations, and we obtain the disorder induced superfluid order parameter and chemical potential through a self-consistent calculation. We also calculate the condensate fraction which reveals a distinct nonmonotonic behavior. The downturn in the latter result occurs at the crossover regime with gradual depletion on the BEC side. The non-monotonic feature in the condensate fraction data has been measured in clean systems. Motivated by the above result, we discuss the stability of a disordered fermionic superfluid in the crossover regime. [ABSTRACT FROM AUTHOR]

We derive the general effective-medium expression for the surface-guided magnetic polaritons and magnetostatic waves, which propagate in the antiferromagnetic superlattice with antiferromagnetic impurity film, and investigate the influence of the external magnetic field on the energy of localized magnetic polaritons. Similarly as in the free-standing antiferromagnetic film, the spectrum of magnetic polaritons in the presence of an external magnetic field is reciprocal in the sense that the frequency is independent of the direction of propagation. In the system under consideration one finds both the surface polaritons which are strongly localized in the antiferromagnetic film which acts as a waveguide, and waves which are weakly localized within film. The first waves are the pure surface modes or guided modes where excitations have a standing-wave-like character. This important feature of the localized magnetic polaritons enables us to use these antiferromagnetic systems in the technologies for devices (for example, in resonators) that work at wavelengths in the infrared region. Second waves have the very small value of the decay parameter and appear in the regions where the surface mode penetrates into the bulk band, i.e. the magnetic polaritons are weakly localized in the impurity film region. Now we obtain the mixed type mode having both bulk and surface characteristics. Also, the general way in which the dispersion curves vary with the volume fraction of the superlattice components and with impurity film is illustrated in this study. [ABSTRACT FROM AUTHOR]

We report magnetic susceptibility measurements of RB (R = Gd, Tb, Ho, Er, and Lu) boron-rich rare earth containing borides down to 50 mK. The data suggest a spin glass low temperature state for RB (R = Gd, Tb, Ho, and Er) with the freezing temperatures below 1 K. The magnetic properties appear to be influenced by the anisotropy of the magnetic moments, probably via the crystalline electric field effects. [ABSTRACT FROM AUTHOR]

We study the coherent transport in a one-dimensional lead with two side-coupled quantum dots using the Keldysh’s Green function formalism.The effect of the interdot Coulomb interaction is taken into account by computing the firstand second order contributions to the self-energy.We show that the Fano interference due to the resonance of one dotis strongly affected by the fixed parameters that characterize the second dot. If the second dot is tuned close to resonance an additionalpeak develops between the peak and dip of the Fano line shape of the current. In contrast, when the second dotis off-resonance and its occupation number is close to unity the interdot Coulomb interaction merely shifts the Fano line and no other maxima appear.The system we consider is more general than the single-dot interferometer studied experimentally by Kobayashi et al. [Phys. Rev. B 70, 035319 (2004)] and may be used for controlling quantum interference and studying decoherence effects in mesoscopic transport. [ABSTRACT FROM AUTHOR]

Abstract   We study the ground-state properties of a Bose-Einstein condensate (BEC) with the short-range repulsion and gravitylike 1/r interatomic attraction in two-dimensions (2D). Using the variational approach, we obtain the ground-state energy and show that the condensate is stable for all interaction strenghts in 2D. We also determine the collective excitations at zero temperature using the time-dependent variational method. We analyze the properties of the Thomas-Fermi-gravity (TF-G) and gravity (G) regimes. [ABSTRACT FROM AUTHOR]

We consider the quasi-particle properties such as the effective mass and spin susceptibility of quasi-two-dimensional electron systems. The finite quantum well width effects are incorporated into the local-field factors that describe the charge and spin correlations. We employ the Fermi-hypernetted chain formalism in conjunction with fluctuation-dissipation theorem to obtain the local-field factors. Our results are in good agreement with recent experiments. [ABSTRACT FROM AUTHOR]

No Heading We consider a trapped system of atomic boson-fermion mixture with a quantized vortex. We investigate the density profiles of bosonic and fermionic components as functions of the boson-boson and boson-fermion short-range interaction strengths within the mean-filed approach. Stability of a vortex and conditions for the phase segregation are studied. We compare and contrast our results with the related system of droplets of 3He-4He mixtures. [ABSTRACT FROM AUTHOR]

We study the dynamical correlation effects in a one-dimensional Fermion gas with repulsive delta-function interaction within the quantum version of the self-consistent field approximation of Singwi, Tosi, Land, and Sjölander [Phys. Rev. 176, 589 (1968)]. The dynamic correlation effects are described by a frequency dependent local-field correction . There is a corresponding local-field factor for the spin-density correlations. We investigate the structure factors, spin-dependent pair-correlation functions, the frequency dependences of and , and the plasmon dispersion relation within this formalism. We compare our results with other theoretical approaches, in particular the static version of the self-consistent field approximation to highlight the importance of dynamical correlations. [ABSTRACT FROM AUTHOR]

The upper critical field B c2 of the organic superconductor λ-(BETS)2GaCl4 has been determined from resistance measurements for orientation of the magnetic field along three perpendicular crystallographic directions. The Ginzburg–Landau coherence length was estimated from the slope of B c2( T) curve near T c as 12.5 nm, 1.6 nm, and 12.5 nm for the a*-, b*-, and c-directions. Angular dependence of the critical field within highly conducting ac plane at 1.5 K was shown to possess two-fold symmetry, which can be related to the band structure anisotropy. [ABSTRACT FROM AUTHOR]

Electromigration stability of TlBaCuO ceramics is shown to decrease significantly when the material is treated in water vapor atmosphere. The T decrease in these samples is accompanied by a resistance increase, while the Seebeck coefficient, S, remains unchanged. The authors conclude that the main effect comes from grain-boundary degradation under the water vapor treatment. For initial samples, electromigration stability strongly depends on the sample oxygen doping level and increases for materials with higher oxygen content. The effect is assumed to be due to the filling of interstitials in Tl-O layers by oxygen atoms. [ABSTRACT FROM AUTHOR]

We study the spin correlations in two- and three-dimensional electron liquids within the sum-rule version of the self-consistent field approach of Singwi, Tosi, Land, and Sjölander. Analytic expressions for the spin-antisymmetric static structure factor and the corresponding local-field correction are obtained with density dependent coefficients. We calculate the spin-dependent pair-correlation functions, paramagnon dispersion, and static spin-response function within the present model, and discuss the spin-density wave instabilities in double-layer electron systems. [ABSTRACT FROM AUTHOR]

In terms of the Blonder-Tinkham-Klapwjik theory, the differential conductivity of Ho(NiB)[sub 2]C/Ag point contacts is explained by the coexistence of magnetic ordering and superconductivity in holmium boron carbides. [ABSTRACT FROM AUTHOR]

The insulating state of κ-(BEDT-TTF)[sub 2]Cu[N(CN)[sub 2]]I salt appearing at ambient pressure at low temperatures is suppressed by hydrostatic pressure. The resistive measurements showed that the emerging metallic state reveals superconductivity in high-quality crystals. The superconducting state with the transition temperature of about 8 K is stable at pressures higher than 0.1 GPa. © 2001 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

We have synthesized the organic conductor (BEDT-TTF)AgI (X ≅ 1.8 and Y≅ 2.9). This compound has, in addition to high electronic conductivity (σ ≅ 5-10 Ω · cm), significant ionic conductivity connected with the motion of silver ions. The value of this ionic conductivity at room temperature is 10 Ω · cm. The activation energy for diffusion of Ag ions is equal to 0.2 eV. [ABSTRACT FROM AUTHOR]

The electrical and optical properties of four charge-transfer complexes based on a molecule of tetracyanoquinodimethane (an acceptor) and donor molecules of quaternary salts of amines have been studied. It has been shown that the conductivity of the complexes has a semiconductor character and is determined by conduction along stacks of tetracyanoquinodimethane molecules. [ABSTRACT FROM AUTHOR]

The response of superconductors to controlled introduction of point-like disorder is an important tool to probe their microscopic electronic collective behavior. In the case of iron-based superconductors, magnetic fluctuations presumably play an important role in inducing high-temperature superconductivity. In some cases, these two seemingly incompatible orders coexist microscopically. Therefore, understanding how this unique coexistence state is affected by disorder can provide important information about the microscopic mechanisms involved. In one of the most studied pnictide family, hole-doped Ba1−xKxFe2As2 (BaK122), this coexistence occurs over a wide range of doping levels, 0.16 ≲ x ≲ 0.25. We used relativistic 2.5 MeV electrons to induce vacancy-interstitial (Frenkel) pairs that act as efficient point-like scattering centers. Upon increasing dose of irradiation, the superconducting transition temperature Tc decreases dramatically. In the absence of nodes in the order parameter this provides a strong support for a sign-changing s± pairing. Simultaneously, in the normal state, there is a strong violation of the Matthiessen's rule and a decrease (surprisingly, at the same rate as Tc) of the magnetic transition temperature Tsm, which indicates the itinerant nature of the long-range magnetic order. Comparison of the hole-doped BaK122 with electron-doped Ba(FexCo1−x)2As2 (FeCo122) with similar Tsm ~ 110 K, x = 0.02, reveals significant differences in the normal states, with no apparent Matthiessen's rule violation above Tsm on the electron-doped side. We interpret these results in terms of the distinct impact of impurity scattering on the competing itinerant antiferromagnetic and s± superconducting orders. [ABSTRACT FROM AUTHOR]

Unconventional superconductivity usually originates from several strongly coupled degrees of freedom, such as magnetic, charge and elastic. A highly anisotropic electronic phase, not driven by lattice degrees of freedom, has been proposed in some of these superconductors, from cuprates to iron-based compounds. In the iron pnictide BaFe2As2, this nematic phase arises in the paramagnetic phase and is present for wide doping and temperature ranges. Here we probe the in-plane electronic anisotropy of electron- and hole-doped BaFe2As2 compounds. Unlike other materials, the resistivity anisotropy behaves very differently for electron- and hole-type dopants and even changes sign on the hole-doped side. This behaviour is explained by Fermi surface reconstruction in the magnetic phase and spin-fluctuation scattering in the paramagnetic phase. This unique transport anisotropy unveils the primary role played by magnetic scattering, demonstrating the close connection between magnetism, nematicity and unconventional superconductivity. [ABSTRACT FROM AUTHOR]