Collapse on the line - how synthetic dimensions influence nonlinear effects.

Power induced wave collapse is one of the most fascinating phenomena in optics as it provides extremely high intensities, thus stimulating a range of nonlinear processes. For low power levels, propagation of beams in bulk media is dominated by diffraction, while above a certain threshold self-focusing is steadily enhanced by the action of a positive nonlinearity. An autocatalytic blow-up occurs, which is only stopped by saturation of the nonlinearity, material damage or the inherent medium discreteness. In the latter case, this leads to energy localization on a single site. It is commonly believed that for cubic nonlinearities, this intriguing effect requires at least two transverse dimensions to occur and is thus out of reach in fiber optics. Following the concept of synthetic dimensions, we demonstrate that mixing short and long-range interaction resembles a two-dimensional mesh lattice and features wave collapse at mW-power levels in a genuine 1D system formed by coupled fiber loops.

Kapitza light guiding in photonic mesh lattice.

We experimentally demonstrate the transverse confinement of light in the presence of a longitudinally periodic photonic potential with vanishing average. In agreement with Kapitza's original findings in classical mechanics, we confirm that light undergoes a transverse localization due to the action of an effective potential proportional to the square of the first derivative of the potential. Experiments are performed based on (1+1) D synthetic dimensions realized in a fiber loop system, allowing for complete control of the transverse and longitudinal distributions of the potential.

2D Solitons in PT-Symmetric Photonic Lattices.

Over the last few years, parity-time (PT) symmetry has been the focus of considerable attention. Ever since, pseudo-Hermitian notions have permeated a number of fields ranging from optics to atomic and topological physics, as well as optomechanics, to mention a few. Unlike their Hermitian counterparts, nonconservative systems do not exhibit a priori real eigenvalues and hence unitary evolution. However, once PT symmetry is introduced, such dissipative systems can surprisingly display a real eigenspectrum, thus ensuring energy conservation during evolution. In optics, PT symmetry can be readily established by incorporating, in a balanced way, regions having an equal amount of optical gain and loss. However, thus far, all optical realizations of such PT symmetry have been restricted to a single transverse dimension (1D), such as arrays of optical waveguides or active coupled cavity arrangements. In most cases, only the loss function was modulated-a restrictive aspect that is only appropriate for linear systems. Here, we present an experimental platform for investigating the interplay between PT symmetry and nonlinearity in two-dimensional (2D) environments, where nonlinear localization and soliton formation can be observed. In contrast to typical dissipative solitons, we demonstrate a one-parameter family of soliton solutions that are capable of displaying attributes similar to those encountered in nonlinear conservative arrangements. For high optical powers, this new family of PT solitons tends to collapse on a discrete network-thus giving rise to an amplified, self-accelerating structure.

Clinical manifestations in individuals with recent diagnosis of HTLV type I infection.

BACKGROUND: Human T-lymphotropic virus type 1 (HTLV-1) is known to cause HTLV-associated myelopathy (HAM)/tropical spastic paraparesis and adult T cell leukemia. A growing body of evidence links HTLV-1 infection with an increasing spectrum of disease, including uveitis, periodontal disease, arthropathy, sicca syndrome, and neurologic deficits. OBJECTIVES: Despite recent findings, the natural history of HTLV-1 infection remains poorly defined. This study was designed to better characterize initial clinical and neurological findings in individuals diagnosed with HTLV-1 infection. STUDY DESIGN: We conducted a cross-sectional study of 71 individuals recently diagnosed with HTLV-1 and 71 uninfected age- and sex-matched blood donors in Salvador, Brazil. Subjects were administered a standardized questionnaire and underwent physical exam. RESULTS: HTLV-1 infected subjects were significantly more likely than controls to report complaints of hand and foot numbness (OR=5.3; 95% CI: 1.8-15.3; p=0.002 and OR=4.0; 95% CI: 1.3-12; p=0.013 respectively), difficulty running (OR=4.0; 95% CI: 1.1-14.2; p=0.032), nocturia (OR=5.0; 95% CI: 1.1-22.8; p=0.038), arthralgia (OR=3.3; 95% CI: 1.4-7.7; p=0.006), and photophobia (OR=3.3; 95% CI: 1.4-7.7; p=0.006). CONCLUSIONS: Neurologic, ocular and rheumatologic complaints may be the first manifestations of HTLV-1 infection. Therefore, all patients presenting with initial diagnosis should be rigorously screened for these symptoms.

Prevalence of erectile dysfunction in HTLV-1-infected patients and its association with overactive bladder.

OBJECTIVES: To determine the prevalence of erectile dysfunction (ED) in human T-cell lymphotropic virus type I (HTLV-I)-infected patients, and its association with overactive bladder (OB). METHODS: In a cross-sectional study, 111 male patients with positive serology for HTLV-I (by enzyme-linked immunosorbent assay and Western blot) were examined between October 2003 and December 2006. Exclusion criteria were age <18 and >80 years, other neurological diseases, penile prosthesis, neoplasm, and psychological and mental disease. Patients were evaluated by a urologist and neurologist. ED was determined by application of the abridged form of 5-item International Index of Erectile Function (IIEF-5). ED was defined as IIEF-5 0 e 2). Diagnosis of HAM/TSP was performed according to World Health Organization recommendations. RESULTS: Of the total of 111 patients, 6 were excluded and 105 were analyzed. The mean age was 48 +/- 10.7 years. ED was observed in 55.2%. ED was documented in all patients who had HAM/TSP, in 79% of the group with EDSS > 0 and

Brain magnetic resonance imaging white matter lesions are frequent in HTLV-I carriers and do not discriminate from HAM/TSP.

Human T lymphotropic virus (HTLV)-I is known to cause HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other pronounced disease in less than 4% of those infected. However, evidence is accumulating that a proportion of HTLV-I carriers have neurological and urological symptoms without fulfilling criteria for HAM/TSP. Brain white matter (WM) lesions on magnetic resonance imaging (MRI) are frequently seen in HAM/TSP. HTLV-I carriers with MRI scans for other neurological diagnoses have WM lesions more frequently than expected. We studied 10 patients with HAM/TSP and 20 HTLV-I carriers without overt neurological disease and evaluated clinical characteristics, viral load, total, small, large, confluent WM lesion number, and lesion volume on MRI. Cerebral WM lesions were found in of 85% of HTLV-I carriers and 80% of HAM/TSP patients. Lesion number, size or location was no different between carriers and HAM/TSP. Cognitive function was lower in HAM/TSP (p = 0.045) but did not correlate with WM lesion number. Viral load and peripheral blood mononuclear cell interferon production correlated positively (p = 0.001) but did not correlate with lesion number or volume. Conventional brain MRI frequently shows WM lesions in HTLV-I-infected individuals suggesting potential early central nervous system inflammation with rare development of progressive disease.

Clinical manifestations associated with HTLV type I infection: a cross-sectional study.

Human T-lymphotropic virus type I (HTLV-I) causes HTLV-I-associated myelopathy/tropical spastic paraparesis and adult T cell leukemia in a small percentage of infected individuals. HTLV-I infection is increasingly associated with clinical manifestations. To determine the prevalence of clinical manifestations in HTLV-I infected individuals, we conducted a cross-sectional study of 115 HTLV-I-infected blood donors without myelopathy and 115 age- and sex-matched seronegative controls. Subjects answered a standardized questionnaire and underwent physical examination. Compared with controls, HTLV-I-infected subjects were more likely to report arm or leg weakness (OR = 3.8, 95% CI: 1.4-10.2; OR = 4.0, 95% CI: 1.6-9.8, respectively), hand or foot numbness (OR = 2.1, 95% CI: 1.1-3.9; OR = 4.8, 95% CI: 2.0-11.7, respectively), arthralgia (OR = 3.3, 95% CI: 1.7-6.4), nocturia (OR = 2.7, 95% CI: 1.04-6.8), erectile dysfunction (OR = 4.0, 95% CI: 1.6-9.8), and to have gingivitis (OR = 3.8, 95% CI: 1.8-7.9), periodontitis (OR = 10.0, 95% CI: 2.3-42.8), and dry oral mucosa (OR = 7.5, 95% CI: 1.7-32.8). HTLV-I infection is associated with a variety of clinical manifestations, which may occur in patients who have not developed myelopathy.

The cause of urinary symptoms among Human T Lymphotropic Virus Type I (HLTV-I) infected patients: a cross sectional study.

BACKGROUND: HTLV-I infected patients often complain of urinary symptomatology. Epidemiological studies have suggested that these individuals have a higher prevalence and incidence of urinary tract infection (UTI) than seronegative controls. However, the diagnosis of UTI in these studies relied only on patient information and did not require confirmation by urine culture. The purpose of this study was to investigate the role of urinary tract infection (UTI) as the cause of urinary symptoms in HTLV-I infected patients. METHODS: In this cross sectional study we interviewed, and cultured urine from, 157 HTLV-I seropositive individuals followed regularly at a specialized clinic. All patients were evaluated by a neurologist and classified according to the Expanded Disability Status Scale (EDSS). Urodynamic studies were performed at the discretion of the treating physician. RESULTS: Sixty-four patients complained of at least one active urinary symptom but UTI was confirmed by a positive urine culture in only 12 of these patients (19%); the majority of symptomatic patients (81%) had negative urine cultures. To investigate the mechanism behind the urinary complaints in symptomatic individuals with negative urine cultures, we reviewed the results of urodynamic studies performed in 21 of these patients. Most of them (90.5%) had abnormal findings. The predominant abnormalities were detrusor sphincter hyperreflexia and dyssynergia, findings consistent with HTLV-I-induced neurogenic bladder. On a multivariate logistic regression, an abnormal EDSS score was the strongest predictor of urinary symptomatology (OR 9.87, 95% CI 3.465 to 28.116, P < 0.0001). CONCLUSION: Urinary symptomatology suggestive of UTI is highly prevalent among HTLV-I seropositive individuals but true UTI is responsible for the minority of cases. We posit that the main cause of urinary symptoms in this population is neurogenic bladder. Our data imply that HLTV-I infected patients with urinary symptomatology should not be empirically treated for UTI but rather undergo urine culture; if a UTI is excluded, further investigation with urodynamic studies should be considered.

Helminthic infection down-regulates type 1 immune responses in human T cell lymphotropic virus type 1 (HTLV-1) carriers and is more prevalent in HTLV-1 carriers than in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis.

Human T cell lymphotropic virus type 1 (HTLV-1) infection is associated with an exacerbated type 1 immune response and secretion of high levels of proinflammatory cytokines. In contrast, helminthic infection induces a type 2 immune response. In the present study, the cytokine profile in HTLV-1 carriers coinfected with helminths (Strongyloides stercoralis and/or Schistosoma mansoni) was compared with that in HTLV-1 carriers not coinfected with helminths. Levels of interferon (IFN)- gamma were higher in HTLV-1 carriers not coinfected with helminths than in HTLV-1 carriers coinfected with helminths (P<.05). The overall frequency of IFN- gamma -expressing CD8+ and CD4+ cells was decreased in HTLV-1 carriers coinfected with helminths (P<.05). The percentage of interleukin (IL)-5- and IL-10-expressing T cells in HTLV-1 carriers coinfected with helminths was higher than that in HTLV-1 carriers not coinfected with helminths (P<.05). Moreover, we found that the prevalence of helminthic infection was 7-fold higher in HTLV-1 carriers than in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (P<.05). These data show that helminthic infection decreases activation of type 1 cells, which may influence the clinical outcome of HTLV-1 infection.