Kustaanheimo-Stiefel Regularization and the Quadrupolar Conjugacy

In this note, we present the Kustaanheimo-Stiefel regularization in a symplectic and quaternionic fashion. The bilinear relation is associated with the moment map of the $S^{1}$- action of the Kustaanheimo-Stiefel transformation, which yields a concise proof of the symplecticity of the Kustaanheimo-Stiefel transformation symplectically reduced by this circle action. The relation between the Kustaanheimo-Stiefel regularization and the Levi-Civita regularization is established via the investigation of the Levi-Civita planes. A set of Darboux coordinates (which we call Chenciner-F\'ejoz coordinates) is generalized from the planar case to the spatial case. Finally, we obtain a conjugacy relation between the integrable approximating dynamics of the lunar spatial three-body problem and its regularized counterpart, similar to the conjugacy relation between the extended averaged system and the averaged regularized system in the planar case.Comment: 19 pages, corrected versio

Candida bracarensis, an emerging yeast involved in human infections

Sir, Invasive candidiasis is an increasingly detected complication in hospitalized adult patients, due to an increase in patients at risk (patients admitted to intensive care units, post-surgical patients, neutropenic and immunosuppressed patients). Non- albicans Candida species have increased in multiple centers and new species are proposed. This is the case of Candida nivariensis and Candida bracarensis that are phylogenetically related with C. glabrata, although with sufficiently genotypically different to justify their assignment as separate species..

Volume-preserving normal forms of Hopf-zero singularity

A practical method is described for computing the unique generator of the algebra of first integrals associated with a large class of Hopf-zero singularity. The set of all volume-preserving classical normal forms of this singularity is introduced via a Lie algebra description. This is a maximal vector space of classical normal forms with first integral; this is whence our approach works. Systems with a non-zero condition on their quadratic parts are considered. The algebra of all first integrals for any such system has a unique (modulo scalar multiplication) generator. The infinite level volume-preserving parametric normal forms of any non-degenerate perturbation within the Lie algebra of any such system is computed, where it can have rich dynamics. The associated unique generator of the algebra of first integrals are derived. The symmetry group of the infinite level normal forms are also discussed. Some necessary formulas are derived and applied to appropriately modified R\"{o}ssler and generalized Kuramoto--Sivashinsky equations to demonstrate the applicability of our theoretical results. An approach (introduced by Iooss and Lombardi) is applied to find an optimal truncation for the first level normal forms of these examples with exponentially small remainders. The numerically suggested radius of convergence (for the first integral) associated with a hypernormalization step is discussed for the truncated first level normal forms of the examples. This is achieved by an efficient implementation of the results using Maple

Equilibria, periodic orbits around equilibria, and heteroclinic connections in the gravity field of a rotating homogeneous cube

This paper investigates the dynamics of a particle orbiting around a rotating homogeneous cube, and shows fruitful results that have implications for examining the dynamics of orbits around non-spherical celestial bodies. This study can be considered as an extension of previous research work on the dynamics of orbits around simple shaped bodies, including a straight segment, a circular ring, an annulus disk, and simple planar plates with backgrounds in celestial mechanics. In the synodic reference frame, the model of a rotating cube is established, the equilibria are calculated, and their linear stabilities are determined. Periodic orbits around the equilibria are computed using the traditional differential correction method, and their stabilities are determined by the eigenvalues of the monodromy matrix. The existence of homoclinic and heteroclinic orbits connecting periodic orbits around the equilibria is examined and proved numerically in order to understand the global orbit structure of the system. This study contributes to the investigation of irregular shaped celestial bodies that can be divided into a set of cubes.Comment: 29 pages, 16 figures, accepted for publication in Astrophysics & Space Scienc

Penicillin susceptibility among invasive MSSA infections: a multicentre study in 16 Spanish hospitals

Objectives: To determine the prevalence of penicillin susceptibility among MSSA causing bloodstream infections (BSIs) in 16 Spanish hospitals and to characterize the penicillin-susceptible MSSA (MSSA-PENS) isolates. Methods: A total of 1011 Staphylococcus aureus isolates were collected from blood cultures in 16 Spanish hospitals during 2018–19 (6–12 months) and their susceptibility to 18 antimicrobials was determined. The MSSA-PENS isolates were selected and examined by PCR to determine the presence of the blaZ gene, other resistance genes and the genes lukF/lukS-PV, eta, etb and tst. The immune evasion cluster (IEC) type was also analysed. All the MSSA-PENS isolates were submitted to S. aureus protein A (spa) typing and the clonal complexes (CCs) were assigned according to their spa type. Results: The prevalence of MSSA was 74.6% (754/1011) and 14.9% (151/1011) were MSSA-PENS-blaZnegative. MSSA-PENS-blaZnegative isolates (n = 151) were ascribed to 88 spa types and 11 CCs. The most frequent CCs were CC5 (35/151) and CC398 (25/151), with t002-CC5 and t571-CC398 being the most common lineages. Pan-susceptibility was identified in 117 of the 151 MSSA-PENS-blaZnegative isolates (77.5%). In the remaining isolates, erythromycin and clindamycin resistance was the most frequent resistance found, although tobramycin, ciprofloxacin, fusidic acid, mupirocin and/or tetracycline resistance was also detected. Thirty-eight MSSA-PENS-blaZnegative isolates were IEC negative and four isolates were Panton–Valentine leucocidin (‘PVL’) positive. Conclusions: A high penicillin susceptibility rate was detected among MSSA, opening therapeutic opportunities for BSIs. The emergence of new successful MSSA-PENS clones could be responsible for these data. The detection among MSSA-PENS-blaZnegative isolates of the clonal lineage CC398 or the absence of an IEC raises questions about their possible animal origin, requiring further analysis

Periodic orbits in the gravity field of a fixed homogeneous cube

In the current study, the existence of periodic orbits around a fixed homogeneous cube is investigated, and the results have powerful implications for examining periodic orbits around non-spherical celestial bodies. In the two different types of symmetry planes of the fixed cube, periodic orbits are obtained using the method of the Poincar\'e surface of section. While in general positions, periodic orbits are found by the homotopy method. The results show that periodic orbits exist extensively in symmetry planes of the fixed cube, and also exist near asymmetry planes that contain the regular Hex cross section. The stability of these periodic orbits is determined on the basis of the eigenvalues of the monodromy matrix. This paper proves that the homotopy method is effective to find periodic orbits in the gravity field of the cube, which provides a new thought of searching for periodic orbits around non-spherical celestial bodies. The investigation of orbits around the cube could be considered as the first step of the complicated cases, and helps to understand the dynamics of orbits around bodies with complicated shapes. The work is an extension of the previous research work about the dynamics of orbits around some simple shaped bodies, including a straight segment, a circular ring, an annulus disk, and simple planar plates.Comment: 23 pages, 10 figures, accepted for publication in Astrophysics & Space Scienc

Lack of EGFR catalytic activity in hepatocytes improves liver regeneration following DDC-induced cholestatic injury by promoting a pro-restorative inflammatory response

Despite the well-known hepatoprotective role of the epidermal growth factor receptor (EGFR) pathway upon acute damage, its specific actions during chronic liver disease, particularly cholestatic injury, remain ambiguous and unresolved. Here, we analyzed the consequences of inactivating EGFR signaling in the liver on the regenerative response following cholestatic injury. For that, transgenic mice overexpressing a dominant negative mutant human EGFR lacking tyrosine kinase activity (ΔEGFR) in albumin-positive cells were submitted to liver damage induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC), an experimental model resembling human primary sclerosing cholangitis. Our results show an early activation of EGFR after 1–2 days of a DDC-supplemented diet, followed by a signaling switch-off. Furthermore, ΔEGFR mice showed less liver damage and a more efficient regeneration following DDC injury. Analysis of the mechanisms driving this effect revealed an enhanced activation of mitogenic/survival signals, AKT and ERK1/2-MAPKs, and changes in cell turnover consistent with a quicker resolution of damage in response to DDC. These changes were concomitant with profound differences in the profile of intrahepatic immune cells, consisting of a shift in the M1/M2 balance towards M2 polarity, and the Cd4/Cd8 ratio in favor of Cd4 lymphocytes, overall supporting an immune cell switch into a pro-restorative phenotype. Interestingly, ΔEGFR livers also displayed an amplified ductular reaction, with increased expression of EPCAM and an increased number of CK19-positive ductular structures in portal areas, demonstrating an overexpansion of ductular progenitor cells. In summary, our work supports the notion that hepatocyte-specific EGFR activity acts as a key player in the crosstalk between parenchymal and non-parenchymal hepatic cells, promoting the pro-inflammatory response activated during cholestatic injury and therefore contributing to the pathogenesis of cholestatic liver disease. © 2022 The Pathological Society of Great Britain and Ireland.This work was supported by the Ministry of Science,Innovation and Universities (MICIU) and AgenciaEstatal de Investigacion (AEI), Spain (co-funded byFEDER funds/Development Fund–a Way to BuildEurope): RTI2018-099098-B-100 to AS/BH andRTI2018-094052-B-100 to AMV; and the RamonAreces Foundation: 20th National Competition forScientific and Technical Research in Life and MatterScience (2020) to IF. NL and JGS were recipients ofresearch assistant contracts linked to grant SAF2015-69145-R and RTI2018-099098-B-100, respectively. CMR was the recipient of a researchcontract (PEJD-2019-POST/BMD-16090) from the Education, Universities, Research and Spokesperson Counseling of the Community of Madrid

Efectos y seguridad del perfluorohexiloctano en la superficie ocular y el endotelio corneal

Objetivo Evaluar los efectos y la seguridad del perfluorohexiloctano (F6H8) tópico en la superficie ocular y el endotelio corneal. Métodos Fueron diagnosticados 45 pacientes (90 ojos) de enfermedad de ojo seco, se seleccionaron y se les prescribió tratamiento con F6H8 durante 6 meses. Las variables en la tinción corneal se documentaron usando la escala National Eye Institute/Industry Workshop (NEI), las variables conjuntivales usando la escala Oxford y los parámetros corneales, como el espesor corneal central, la densidad celular, el coeficiente de variación, la hexagonalidad y el área celular promedio, al inicio del estudio, a los 3 meses y a los 6 meses. Se evaluó también el cumplimiento y la satisfacción. Resultados El tratamiento con F6H8 redujo la tinción corneal promedio en pacientes cumplidores a una media de -0, 84 ± 1, 95 a los 3 meses (p = 0, 001) y a -1, 65 ± 2, 42 a los 6 meses (p < 0, 001). La tinción conjuntival a los 6 meses mostró una disminución promedio de -0, 13 (p = 0, 319). Los parámetros endoteliales no mostraron diferencia significativa, excepto el espesor corneal central, que mostró una disminución estadísticamente significativa (era de 545, 30 ± 32, 25 µm al comienzo del estudio y 538, 40 ± 31, 36 µm tras 6 meses, p = 0, 009). Al final del estudio, el 46% de los pacientes informaron sentirse subjetivamente mejor, el 40, 5% no sintió cambios y el 13, 5% se sintió subjetivamente peor. Conclusiones El tratamiento tópico con F6H8 para la enfermedad de ojo seco no alteró las variables medidas del endotelio corneal, aunque sí mostró mejoría en la tinción corneal y en la satisfacción. Objective: To evaluate the effects and safety of topical drops of perfluorohexyloctane (F6H8) on the ocular surface and the corneal endothelium. Methods: Forty-five patients (90 eyes) diagnosed with dry eye disease were recruited and prescribed treatment with F6H8 as part of a six-month prospective multicentre study. Variables in corneal staining were documented using the National Eye Institute/Industry Workshop scale. The conjunctival variables included using the Oxford scale, as well as corneal parameters, such as central corneal thickness, cell density, coefficient of variation, hexagonality, and mean cell area, at the start of the study, and at 3 months and 6 months. Compliance and satisfaction with the treatment were measured. Results: F6H8 drops reduced mean corneal staining based on the NEI scale in compliant patients to a mean of -0.84 ± 1.95 at 3 months (P=.001) and to -1.65 ± 2.42 at 6 months (P<.001). Conjunctival staining at 6 months showed a mean decrease of -0.13 (P=.319). The endothelial parameters did not show a significant difference, in contrast to the central corneal thickness that showed a statistically significant decrease (545.30 ± 32.25 at the start of the study to 538.40 ± 31.36 after 6 months, P=.009). At the end of the study, 46% of patients reported feeling subjectively better, 40.5% felt the same, and 13.5% felt subjectively worse. Conclusions: Topical treatment with F6H8 for dried eye disease did not alter the measured variables of the corneal endothelium, but showed improvement in corneal staining and satisfaction