Projected Entangled Pair States: Fundamental Analytical and Numerical Limitations.

Matrix product states and projected entangled pair states (PEPS) are powerful analytical and numerical tools to assess quantum many-body systems in one and higher dimensions, respectively. While matrix product states are comprehensively understood, in PEPS fundamental questions, relevant analytically as well as numerically, remain open, such as how to encode symmetries in full generality, or how to stabilize numerical methods using canonical forms. Here, we show that these key problems, as well as a number of related questions, are algorithmically undecidable, that is, they cannot be fully resolved in a systematic way. Our work thereby exposes fundamental limitations to a full and unbiased understanding of quantum many-body systems using PEPS.

Retinal Sensitivity in Patients with Type I Diabetes without Retinopathy or with Minor Retinal Changes.

Objective: To evaluate the ability of short-wavelength automated perimetry (SWAP) for the detection of visual impairment in patients with type I diabetes without retinopathy or with minor retinal vascular changes. Design: Comparative cross-sectional study. Participants: 30 eyes of 30 healthy subjects and 73 eyes of 73 patients with type I diabetes mellitus were studied. Methods: Ophthalmic examination of diabetic patients showed no retinopathy or minimal changes (less than 5 microaneurisms in each eye) with no previous laser treatment. All patients were examined by means of the SWAP 24-2 strategy. Mean Deviation (MD) and Pattern Standard Deviation (PSD) were compared between both groups. Results: There were differences in the clusters of altered points between both groups (p=0.004). SWAP MD was lower in the diabetic group than in the controls (-2.89 dB vs. -0.20 dB, p<0.001). SWAP PSD also differed between both groups (2.50 dB in control group, 3.12 dB in the diabetic group, p=0.003). In the diabetic group, mean period from the onset of diabetes was 12.6±6.7 years and minimal vascular changes were observed in the retina of 18 eyes (24.7%), while 55 had no lesions (75.3%). No differences in SWAP changes were found between patients without and with minimal diabetic retinopathy. Conclusions: Retinal sensitivity assessed by SWAP is depressed in patients with type I diabetes regardless of the presence of retinal vascular changes.

Lateral preference in Williams-Beuren syndrome is associated with cognition and language.

Williams-Beuren syndrome (WBS) is a genetically defined neurodevelopmental disorder presenting with intellectual disability associated with a specific neurocognitive profile characterized by anxiety, hypersociability, poor visuospatial skills and relatively preserved language. We have defined the lateral preference in 69 individuals (40 males and 29 females, age range 5-47 years) with WBS confirmed by molecular testing, and explored its correlation with cognition, behavior problems, the main aspects of the behavioral phenotype, and specific molecular variants (parental origin and size of the 7q11.23 deletion). Lateral preference (hand, foot, eye and ear) and neurobehavioral features [intelligence quotient (IQ), sociability, visuospatial construction, narrative skills and behavior] were assessed by a battery of tests and parental interviews. A large proportion of WBS individuals showed either left or mixed handedness (26 and 19%, respectively). Hand, foot and ear lateral preference showed significant association with IQ, with individuals with mixed lateral preference presenting lower general IQ, especially verbal IQ, with respect to subjects with well-defined laterality. Approachability, visuospatial ability, behavior problems or molecular variants were not associated with lateral preference. Our results indicate that, as in other neurodevelopmental disorders, laterality is poorly defined in a significant proportion of WBS individuals, and reinforces the idea that a correct definition of lateral preference is important for cognition and language.

Complicaciones de tapones lagrimales: granuloma piogénico del punto lagrimal / Complicationof punctual plugs insertion: pyogenic granuloma

Caso Clínico. Mujer de 45 años que acude a consultas de oftalmología por sensación de cuerpo extraño al parpadeo. A la exploración presenta una tumoración rojiza en la zona superior del canto interno de su ojo derecho. La paciente era tratada por síndrome de ojo seco, con lágrimas artificiales y suero autólogo. Llevaba tres meses con tapones lagrimales de tamaño mediano. Discusión. Destacamos la importancia de una correcta elección del tamaño del tapón lagrimal para disminuir la probabilidad de complicaciones. Presentamos el caso clínico de un granuloma piogénico del punto y canalículo lagrimal, en una portadora de tapones lagrimales (AU)

Case Report. A 45-year-old female was referred to our department due to foreign-body sensation in her right eye. Biomicroscopy examination showed a red ampullary lesion over the right inferior puncta, clinically diagnosed as pyogenic granuloma. This patient, with a longstanding history of dry eyes, had undergone previous treatment with autologous serum eye drops and preservative-free artificial eye drops. Also, for the last three months she was treated with medium size silicone punctal plugs. Discussion. We report a case of a pyogenic granuloma caused by a silicone lagrimal plug. It is important to emphasize the correct choice of plug size and its appropiate placement. Patients with this devices should be informed about possible complications (AU)

Utilidad de las retinografías en el diagnóstico del edema macular diabético / Use of retinal photography in the diagnosis of diabetic macular edema

Objetivo: Determinar la validez de las retinografías en el diagnóstico del edema macular diabético. Fijar el número y amplitud de las fotografías necesarias para su correcto diagnóstico. Métodos: Estudio observacional transversal constituido por 650 ojos de pacientes con retinopatía diabética, a los que se realizó una combinación de retinografías (simples, estereoscópicas y luz aneritra), previa dilatación, para determinar su validez, en el diagnóstico del edema macular diabético. Se calcularon sensibilidad, especificidad, valores predictivo positivo y negativo, así como la concordancia con la prueba de referencia (tomografía de coherencia óptica). Las fotografías fueron evaluadas por tres expertos y sus resultados analizados con el programa estadístico SPSS 15.0 Windows. Resultados: Se obtuvieron valores de sensibilidad inferiores al 80% en el caso de fotografías simples, superando el 80% las retinografías estereoscópicas o aquellas que asocian filtros verdes, siendo la fotografía estereoscópica verde a 30° la que alcanzó mayor sensibilidad, próxima al 94,3%. La especificidad fue del 95% en el caso de fotografías estereoscópicas en color y aneritra a 45 y 30°, respectivamente. El valor predictivo positivo superior al 95% y negativo del 90% con un coeficiente de acuerdo del 80% y un grado de concordancia con la prueba de referencia superior al 80%. Conclusiones: Las retinografías estereoscópicas ofrecen resultados suficientes, como para ser utilizadas en el cribado del edema macular diabético. La utilización de filtros verde (luz aneritra) y su combinación con la agudeza visual mejora los resultados en el diagnóstico de esta enfermedad (AU)

Objective: To determine the validity of retinal photography in the diagnosis of diabetic macular edema. Determine the number and size of the photographs for its correct diagnosis. Methods: Cross-sectional observational study consisting of 420 eyes of patients with diabetic retinopathy, using a combination of retinography (simple, stereoscopic, red-free light), after expansion, to determine its validity in the diagnosis of diabetic macular edema. Sensitivity, specificity, positive and negative predictive values and the correlation with the gold standard test (optical coherence tomography) were calculated. The retinographs were evaluated by three experts and their results analyzed by the statistical program SPSS 15.0 Windows. Results: Sensitivities were below 80% in simple photographs and above 80% in the stereoscopic retinography, whereas those associated with red-free filters, reaching the 30° green stereoscopic photography, showed a sensitivity of 94.3%. The specificity was 95% in color and red-free stereoscopic retinography of 45° and 30°. The positive predictive value was greater than 95% and the negative value greater than 90% with a coefficient of agreement of 80%, and a degree of consistency with the benchmark of over 80%. Conclusions: The results of the stereoscopic retinographs are sufficient to enable them to be used in screening for diabetic macular edema. The use of a green filter and its combination with visual acuity improves results in the diagnosis of this disease (AU)

[Use of retinal photography in the diagnosis of diabetic macular edema]. / Utilidad de las retinografías en el diagnóstico del edema macular diabético.

OBJECTIVE: To determine the validity of retinal photography in the diagnosis of diabetic macular edema. Determine the number and size of the photographs for its correct diagnosis. METHODS: Cross-sectional observational study consisting of 420 eyes of patients with diabetic retinopathy, using a combination of retinography (simple, stereoscopic, red-free light), after expansion, to determine its validity in the diagnosis of diabetic macular edema. Sensitivity, specificity, positive and negative predictive values and the correlation with the gold standard test (optical coherence tomography) were calculated. The retinographs were evaluated by three experts and their results analyzed by the statistical program SPSS 15.0 Windows. RESULTS: Sensitivities were below 80% in simple photographs and above 80% in the stereoscopic retinography, whereas those associated with red-free filters, reaching the 30° green stereoscopic photography, showed a sensitivity of 94.3%. The specificity was 95% in color and red-free stereoscopic retinography of 45° and 30°. The positive predictive value was greater than 95% and the negative value greater than 90% with a coefficient of agreement of 80%, and a degree of consistency with the benchmark of over 80%. CONCLUSIONS: The results of the stereoscopic retinographs are sufficient to enable them to be used in screening for diabetic macular edema. The use of a green filter and its combination with visual acuity improves results in the diagnosis of this disease.

Lieb-Robinson bounds for spin-boson lattice models and trapped ions.

We derive a Lieb-Robinson bound for the propagation of spin correlations in a model of spins interacting through a bosonic lattice field, which satisfies a Lieb-Robinson bound in the absence of spin-boson couplings. We apply these bounds to a system of trapped ions and find that the propagation of spin correlations, as mediated by the phonons of the ion crystal, can be faster than the regimes currently explored in experiments. We propose a scheme to test the bounds by measuring retarded correlation functions via the crystal fluorescence.

Behavioral features of Williams Beuren syndrome compared to Fragile X syndrome and subjects with intellectual disability without defined etiology.

Williams-Beuren syndrome (WBS) is a genetically determined neurodevelopmental disorder caused by a heterozygous deletion of 26-28 genes on chromosome band 7q11.23. During the past few years, researchers and clinicians have significantly contributed to define the phenotype of the syndrome, including its cognitive and behavioral aspects. However, it is not well known yet whether the psychological problems are specific to the syndrome or secondary to the intellectual disability (ID). The aim of our study was to better define the psychopathological profile of WBS and whether or not it is related with IQ or anxiety symptoms. Twenty-five subjects (12 girls, 13 boys) with a diagnosis of WBS were compared to 27 boys with Fragile X Syndrome and to 24 boys with ID of non-specific etiology using the Child Behavior Checklist. Anxiety, depression and attention problems were the main behavioral problems found in WBS with no gender differences. Significant differences between cohorts were observed in somatic complaints, delinquent behavior, aggressive behavior, and externalizing problems. Some associations between IQ and anxiety items were found. The findings are discussed in terms of behavioral phenotypes, genetic implications and ID.

Operator space theory: a natural framework for bell inequalities.

In this Letter we show that the field of operator space theory provides a general and powerful mathematical framework for arbitrary Bell inequalities, in particular, regarding the scaling of their violation within quantum mechanics. We illustrate the power of this connection by showing that bipartite quantum states with local, Hilbert space dimension n can violate a Bell inequality by a factor of order sqrt[n]/(log{2}n) when observables with n possible outcomes are used. Applications to resistance to noise, Hilbert space dimension estimates, and communication complexity are given.

Sequential implementation of global quantum operations.

We study the possibility for a global unitary applied on an arbitrary number of qubits to be decomposed in a sequential unitary procedure, where an ancillary system is allowed to interact only once with each qubit. We prove that sequential unitary decompositions are in general impossible for genuine entangling operations, even with an infinite-dimensional ancilla, being the controlled-NOT gate a paradigmatic example. Nevertheless, we find particular nontrivial operations in quantum information that can be performed in a sequential unitary manner, as is the case of quantum error correction and quantum cloning.

String order and symmetries in quantum spin lattices.

We show that the existence of string order in a given quantum state is intimately related to the presence of a local symmetry by proving that both concepts are equivalent within the framework of finitely correlated states. Once this connection is established, we provide a complete characterization of local symmetries in these states. The results allow us to understand in a straightforward way many of the properties of string order parameters, like their robustness or fragility under perturbations and their typical disappearance beyond strictly one-dimensional lattices. We propose and discuss an alternative definition, ideally suited for detecting phase transitions, and generalizations to two and more spatial dimensions.

[Suburethral endometrioma]. / Endometrioma suburetral.

Endometriosis is a common disease affecting mostly women in childbearing age. It usually involves the internal pelvic organs but occasionally can present in unusual locations. We report on a 32-year-old nulliparos female presenting with a suburethral painful mass causing obstructive voiding symptoms; she had also a long history of dismenorreia, perimenstrual pelvic pain, urinary tract infections, disúria and dispareunia. The diagnostic work-up revealed a suburethral cystic lesion consistent with a complicated urethral diverticulum or a suburethral endometrioma. Complete surgical excision confirmed an endometriotic cyst. The differential diagnosis of this rare suburethral location of endometriosis with other vaginal cysts is discussed.

Endometrioma suburetral / Suburethral endometrioma

La endometriosis es una enfermedad común que afecta con preferencia a mujeres en edad fértil. Están implicados sobre todo órganos pélvicos internos y de forma ocasional puede tener localizaciones raras. Describimos el caso clínico de una paciente de 32 años de edad con dispareunia, disuria, dolor uretral y masa dolorosa suburetral que condicionaba sintomatología miccional obstructiva. El diagnóstico de sospecha era de un divertículo de uretra complicado o de un endometrioma suburetral. La exéresis quirúrgica realizada confirmó tratarse de un quiste de endometriosis. Se realizan breves comentarios sobre esta localización rara de endometriosis y sus implicaciones en el diagnóstico diferencial con otras entidades quísticas vaginales

Endometriosis is a common disease affecting mostly women in childbearing age. It usually involves the internal pelvic organs but occasionally can present in unusual locations. We report on a 32-year-old nulliparos female presenting with a suburethral painful mass causing obstructive voiding symptoms; she had also a long history of dismenorreia, perimenstrual pelvic pain, urinary tract infections, disúria and dispareunia. The diagnostic work-up revealed a suburethral cystic lesion consistent with a complicated urethral diverticulum or a suburethral endometrioma. Complete surgical excision confirmed an endometriotic cyst. The differential diagnosis of this rare suburethral location of endometriosis with other vaginal cysts is discussed

Criticality, the area law, and the computational power of projected entangled pair states.

The projected entangled pair state (PEPS) representation of quantum states on two-dimensional lattices induces an entanglement based hierarchy in state space. We show that the lowest levels of this hierarchy exhibit a very rich structure including states with critical and topological properties. We prove, in particular, that coherent versions of thermal states of any local 2D classical spin model correspond to such PEPS, which are in turn ground states of local 2D quantum Hamiltonians. This correspondence maps thermal onto quantum fluctuations, and it allows us to analytically construct critical quantum models exhibiting a strict area law scaling of the entanglement entropy in the face of power law decaying correlations. Moreover, it enables us to show that there exist PEPS which can serve as computational resources for the solution of NP-hard problems.

Anxiolytic and antidepressant-like activity of a standardized extract from Galphimia glauca.

An infusion prepared with aerial parts from Galphimia glauca has been widely used in Mexican traditional medicine as a remedy for nervous excitement. The sedative activity of a methanolic extract from this plant has been demonstrated by neuropharmacological tests. This effect was attributed to the nor-secotriterpene named galphimine B (GB). In the present work, the anxiolytic and antidepressant-like effects of G. glauca methanolic extract (standardized on GB content, 8.3mg/g) were assayed by using the elevated plus-maze, light-dark test and the forced swimming paradigm, on ICR albino mice. This extract, administered orally, three times (24, 18 and 1h before the test), and in different doses (125, 250, 500, 1,000 and 2,000 mg/kg) was able to increase significantly (p<0.05) the number of entries, as well as the time spent in the open arms of the elevated plus-maze, indicating an anxiolytic-like effect. A similar effect was observed in the light-dark paradigm test, the time spent in the light box was increased in treated mice. Nevertheless, this treatment was unable to change any parameter in the forced swimming test. Altogether, these results suggest an anxiolytic-like effect to the methanolic standardized extract of G. glauca on ICR inbred mice.

Leiomioma de uretra femenina / Leiomyoma of the female urethra

El leiomioma de la uretra femenina es un tumor mesenquimal benigno, muy poco frecuente en la práctica clínica. Existen controversias sobre su grado de dependencia hormonal estrogénica, y su diagnóstico se efectúa sólo tras el estudio histopatológico de la pieza de resección. Este tipo de tumor, presenta un pronóstico excelente, con escasas recidivas tumorales, y ningún caso de transformación maligna descrito hasta la fecha. Presentamos un caso de leiomioma de uretra femenina, con características clínico-epidemiológicas típicas, pero poco común desde el punto de vista topográfico, al hallarse localizado en la cara anterior de la uretra distal (AU)

[Metachronous tumors of the upper urinary tract following primary superficial tumors of the bladder]. / Tumores del tracto urinario superior metacrónicos subsiguientes a tumores superficiales primarios de vejiga.

OBJECTIVE: To evaluate the long term incidence of upper urinary tract tumours in patients with surface tumours of the bladder. MATERIAL AND METHODS: Analysis of 78 patients with primary tumour of the bladder pTa-pTl diagnosed between 1978 and 1988. These patients were followed for up to 10 to 21 years (mean follow-up 13.4 years) and were treated with transurethral resection and a variety of endovesical cytostatic agents. RESULTS: Of all 78 patients, 9 (11%) developed an upper urinary tract tumour over an average of 9 years (range 4-18); 2 in the first 5 years, 4 between 5 to 10 years, and 3 between 10 and 18 years. The likelihood of finding a tumour in the upper tract if all 20-year old patients were to be followed would be 25.6% (Kaplan-Meier's method). A high percentage of all upper urinary tract tumours are infiltrant, but the cause of death in 44% of these patients is progression of the tumour of the bladder. CONCLUSIONS: The percentage of tumours of the upper urinary tract that become metachronic following a tumour of the bladder, increases with the duration of the follow-up. A high percentage of these cases are already in high stages when diagnosed. It would be convenient to monitor the upper urinary tract with the same periodicity than the bladder in order to establish early diagnoses. These patients show a high mortality rate, in most cases secondary to progression of the tumour of the bladder.

[Bilateral testicular luxation]. / Luxación testicular bilateral.

Contribution of a case report of long-standing bilateral testicular luxation, the result of scrotal trauma caused by a soccer ball. Good aesthetic, endocrine and exocrine results were obtained with surgical treatment. Androgenic hormonal profile and spermiogram performed at six months showed values within the normal range.

Tumores del tracto urinario superior metacrónicos subsiguientes a tumores superficiales primarios de vejiga / Metachronic tumours of the upper urinary tract following primary surface tumours of the bladder

OBJETIVO: Evaluar a largo plazo la incidencia de los tumores del tracto urinario superior, en pacientes con tumores superficiales de vejiga. MATERIAL Y MÉTODOS: Se analizan 78 pacientes con tumor primario de vejiga pTa-pT1 diagnosticados entre 1978 y 1988, seguidos entre 10 y 21 años (seguimiento medio 13,4 años) y tratados con resección transuretral y diferentes citostáticos endovesicales. RESULTADOS: De los 78 pacientes, 9 (11 por ciento) desarrollaron tumor en el tracto urinario superior, en un tiempo medio de 9 años (rango 4-18 años); 2 en los primeros 5 años, 4 entre los 5 y 10 años, y 3 entre los 10 y los 18 años. Las posibilidades de desarrollar un tumor en el tracto superior si se siguiesen todos los pacientes 20 años, serían del 25,6 por ciento (método de Kaplan-Meier). Un porcentaje alto de los tumores del tracto urinario superior son infiltrantes, pero la causa de la muerte en el 44 por ciento de estos pacientes es la progresión del tumor de vejiga. CONCLUSIONES: El porcentaje de tumores del tracto urinario superior, metacrónicos siguientes a un tumor de vejiga se incrementa al aumentar el tiempo de seguimiento. Un porcentaje alto de ellos se diagnostican en esta-dios altos, por lo que sería conveniente monitorizar el aparato urinario superior, con la misma periodicidad que la vejiga, para hacer diagnósticos precoces. Estos pacientes tienen una alta tasa de mortalidad, secundaria en la mayoría de los casos a la progresión del tumor de vejiga (AU)