Segmented Strings in AdS3AdS_3

We study segmented strings in flat space and in $AdS_3$. In flat space, these well known classical motions describe strings which at any instant of time are piecewise linear. In $AdS_3$, the worldsheet is composed of faces each of which is a region bounded by null geodesics in an $AdS_2$ subspace of $AdS_3$. The time evolution can be described by specifying the null geodesic motion of kinks in the string at which two segments are joined. The outcome of collisions of kinks on the worldsheet can be worked out essentially using considerations of causality. We study several examples of closed segmented strings in $AdS_3$ and find an unexpected quasi-periodic behavior. We also work out a WKB analysis of quantum states of yo-yo strings in $AdS_3$ and find a logarithmic term reminiscent of the logarithmic twist of string states on the leading Regge trajectory.Comment: 38 pages, 5 figure

cranial nerve abnormalities in oculo auriculo vertebral spectrum

BACKGROUND AND PURPOSE: Cranial nerve abnormalities might be observed in hemifacial microsomia and microtia (oculo-auriculo-vertebral spectrum), but the rate, features, and relationship with functional impairment or phenotype severity have not yet been defined. This study aimed at investigating absence/asymmetry, abnormal origin, morphology and course of cranial nerves, and presence/asymmetry of the foramen ovale and inferior alveolar nerve canal in a cohort of oculo-auriculo-vertebral spectrum patients. MATERIALS AND METHODS: Twenty-nine patients with oculo-auriculo-vertebral spectrum (mean age, 7 years; age range, 0.2–31 years; 12 females) underwent brain MR imaging, CT, and neurologic evaluation; 19 patients had a more severe phenotype (Goldenhar syndrome). RESULTS: Cranial nerve abnormalities were detected only in patients with Goldenhar syndrome (17/19, bilaterally in 8) and were involved the second (4/19), third (1/18), fifth (11/19), sixth (8/16), seventh (11/18), and eighth (8/18) cranial nerves. Multiple cranial nerve abnormalities were common (11/17). Eleven patients showed bone foramina abnormalities. Trigeminal and facial nerve dysfunctions were common (44% and 58%, respectively), especially in patients with Goldenhar syndrome. Trigeminal abnormalities showed a good correlation with ipsilateral dysfunction ( P = .018), which further increased when bone foramina abnormalities were included. The facial nerve showed a trend toward correlation with ipsilateral dysfunction ( P = .081). Diplopia was found only in patients with Goldenhar syndrome and was associated with third and sixth cranial nerve abnormalities ( P = .006). CONCLUSIONS: Among patients with oculo-auriculo-vertebral spectrum, cranial nerve morphologic abnormalities are common, correlate with phenotype severity, and often entail a functional impairment. The spectrum of cranial nerve abnormalities appears wider than simple hypo-/aplasia and includes an anomalous cisternal course and partial/complete fusion of diverse cranial nerves. CN : cranial nerve OAVS : oculo-auriculo-vertebral spectru

neuroimaging changes in menkes disease part 2

SUMMARY: This is the second part of a retrospective and review MR imaging study aiming to define the frequency rate, timing, imaging features, and evolution of gray matter changes in Menkes disease, a rare multisystem X-linked disorder of copper metabolism characterized by early, severe, and progressive neurologic involvement. According to our analysis, neurodegenerative changes and focal basal ganglia lesions already appear in the early phases of the disease. Subdural collections are less common than generally thought; however, their presence remains important because they might challenge the differential diagnosis with child abuse and might precipitate the clinical deterioration. Anecdotal findings in our large sample seem to provide interesting clues about the protean mechanisms of brain injury in this rare disease and further highlight the broad spectrum of MR imaging findings that might be expected while imaging a child with the suspicion of or a known diagnosis of Menkes disease

Alterations in the Interleukin-1/Interleukin-1 Receptor Antagonist Balance Modulate Cardiac Remodeling following Myocardial Infarction in the Mouse

Background Healing after acute myocardial infarction (AMI) is characterized by an intense inflammatory response and increased Interleukin-1 (IL-1) tissue activity. Genetically engineered mice lacking the IL-1 receptor (IL-1R1-/-, not responsive to IL-1) or the IL-1 receptor antagonist (IL-1Ra, enhanced response to IL-1) have an altered IL-1/IL-1Ra balance that we hypothesize modulates infarct healing and cardiac remodeling after AMI. Methods IL-1R1-/- and IL-1Ra-/- male mice and their correspondent wild-types (WT) were subjected to permanent coronary artery ligation or sham surgery. Infarct size (trichrome scar size), apoptotic cell death (TUNEL) and left ventricular (LV) dimensions and function (echocardiography) were measured prior to and 7 days after surgery. Results When compared with the corresponding WT, IL-1R1-/- mice had significantly smaller infarcts (−25%), less cardiomyocyte apoptosis (−50%), and reduced LV enlargement (LV end-diastolic diameter increase [LVEDD], −20%) and dysfunction (LV ejection fraction [LVEF] decrease, −50%), whereas IL-1Ra-/- mice had significantly larger infarcts (+75%), more apoptosis (5-fold increase), and more severe LV enlargement (LVEDD increase,+30%) and dysfunction (LVEF decrease, +70%)(all P values \u3c0.05). Conclusions An imbalance in IL-1/IL-1Ra signaling at the IL-1R1 level modulates the severity of cardiac remodeling after AMI in the mouse, with reduced IL-1R1 signaling providing protection and unopposed IL-1R1 signaling providing harm

Incised valley paleoenvironments interpreted by seismic stratigraphic approach in Patos Lagoon, Southern Brazil

<div><p>ABSTRACT: The Rio Grande do Sul (RS) coastal plain area (33,000 km 2 ) had its physiography modified several times through the Quaternary, responding to allogenic and autogenic forcings. The Patos Lagoon covers a significant area of RS coastal plain (10,000 km 2 ), where incised valleys were identified in previous works. About 1,000 km of high resolution (3.5 kHz) seismic profiles, radiocarbon datings, Standard Penetration Test (SPT) and gravity cores were analyzed to interpret the paleoenvironmental evolution as preserved in incised valley infills. Seismic facies were recognized by seismic parameters. The sediment cores were used to ground-truth the seismic interpretations and help in the paleoenvironmental identification. Key surfaces were established to detail the stratigraphical framework, and seismic facies were grouped into four seismic units, which one classified in respective system tracts within three depositional sequences. The oldest preserved deposits are predominantly fluvial and estuarine facies, representing the falling stage and lowstand system tracts. The Holocene transgressive records are dominated by muddy material, mainly represented by estuarine facies with local variations. The transgression culminated in Late Holocene deposits of Patos Lagoon, representing the highstand system tract. The depositional pattern of the vertical succession was controlled by eustatic variations, while the autogenic forcing (paleogeography and sediment supply) modulated the local facies variation.</p></div

Descarga sólida em suspensão do sistema fluvial do Guaíba, RS, e sua variabilidade temporal

The suspended load of the Guaíba fluvial system and its temporal variability were assessed. A dataset was assembled gathering river discharge daily data from the main rivers that form the Guaíba (Jacuí, Sinos and Caí rivers), and water turbidity data from a water treatment plant of Water and Sewage Municipal Department (DMAE), recorded at 30 minutes interval. The turbidity data were converted to suspended sediment concentration (SSC) throughout calibration procedures with samples of suspended sediments from the Guaíba. The turbidity monitoring station was also validated for representativeness to the Guaíba waters, with synoptic sampling.  The turbidity data were reduced do mean daily values. The function of the SSC (kg.m-3 ) as function of river discharge (Q, m3 .s-1) was built given the rating curve SSC(Q) = 0.0057 + 0.00450,2884 Q with r2 = 0,68. The suspended load was directly obtained by the product of river discharge and SSC. The results indicated that the suspended load varies considerably along the time, mainly during short period discharge peaks. The major ity of suspended load is carried with river discharge between 1,000 and 3,000 m3 .s-1 , representing 47.2% of the total. The averaged suspended load to Patos Lagoon for the 2003-2006 period was of the order of 1,1 x 106 t/yr, or, of about 400.000 m of sediments (2650 kg/m3 ) from the Guaíba's drainage basin towards the lagoon depositional sites, and further the continental shelf.O presente trabalho apresenta uma avaliação da variação temporal da descarga sólida em suspensão no sistema fluvial do Guaíba. Foi utilizada uma base de dados históricos entre 2003 a 2006, constituída de vazões diárias dos rios afluentes (rios Jacuí, Sinos e Caí), e da turbidez da água monitorada em intervalos de 30 minutos na estação de tratamento de água do Departamento Municipal de Água e Esgoto (DMAE). Os dados de turbidez foram convertidos em concentração de sedimentos em suspensão (CSS) através da calibração do sensor de turbidez com amostras de sedimentos em suspensão coletadas no Guaíba. Também foi realizada uma validação da estação de monitoramento para verificar se os dados obtidos a partir da estação representavam as condições simultâneas no Guaíba. Os dados de turbidez foram reduzidos para médias diárias. Foi elaborada a curva chave de CSS (em kg.m-3) em função da vazão (Q em m3.s-1), representada por CSS(Q) = 0,0057 + 0,0045 Q 0,2884 com r2 = 0,68. A descarga sólida em suspensão foi obtida pelo produto simples entre a vazão e a CSS. Os resultados demonstraram que a descarga sólida em suspensão varia consideravelmente ao logo do tempo, principalmente durante eventos de alta vazão de curta duração. A maior parte dos sedimentos em suspensão é transportada com valores de vazões entre 1.000 e 3.000 m3.s-1 e representou 47,2% do total. O valor médio de descarga sólida transportada para a Lagoa dos Patos entre os períodos de 2003 a 2006 foi da ordem de 1,1 x 106 t/ano, o que representa uma exportação da ordem de 400.000 m3 de sedimentos (2.650 kg/m3) da bacia de drenagem do rio Guaíba para os sistemas deposicionais lagunares e, posteriormente a plataforma continental adjacente

Right Ventricular Dysfunction following Acute Myocardial Infarction in the Absence of Pulmonary Hypertension in the Mouse

Background Cardiac remodelling after AMI is characterized by molecular and cellular mechanisms involving both the ischemic and non-ischemic myocardium. The extent of right ventricular (RV) dilatation and dysfunction and its relation to pulmonary hypertension (PH) following AMI are unknown. The aim of the current study was to evaluate changes in dimensions and function of the RV following acute myocardial infarction (AMI) involving the left ventricle (LV). Methods We assessed changes in RV dimensions and function 1 week following experimental AMI involving the LV free wall in 10 mice and assessed for LV and RV dimensions and function and for the presence and degree of PH. Results RV fractional area change and tricuspidal annular plane systolic excursion significantly declined by 33% (P = 0.021) and 28% (P = 0.001) respectively. Right ventricular systolic pressure measured invasively in the mouse was within the normal values and unchanged following AMI. Conclusion AMI involving the LV and sparing the RV induces a significant acute decline in RV systolic function in the absence of pulmonary hypertension in the mouse indicating that RV dysfunction developed independent of changes in RV afterload