3,834 research outputs found
The impact of the American Civil War on city growth
This paper analyses the persistence of the shock caused by the American Civil War on the relative city size distribution of the USA. Two features make the study of this conflict interesting. First, it took place at an earlier stage of the industrialisation and urbanisation processes than those previously analysed in the related literature. Second, the battles were fought in the open field, not in urban areas. In line with previous results for the Second World War in Japanese and German cities, our findings suggest that the effects of the shock were transitory. Furthermore, some evidence regarding the possible presence of a ‘safe harbour effect’ is reported
Bmi1+ Progenitor Cell Dynamics in Murine Cornea During Homeostasis and Wound Healing
The outermost layer of the eye, the cornea, is renewed continuously throughout life. Stem cells of the corneal epithelium reside in the limbus at the corneal periphery and ensure homeostasis of the central epithelium. However, in young mice, homeostasis relies on cells located in the basal layer of the central corneal epithelium. Here, we first studied corneal growth during the transition from newborn to adult and assessed Keratin 19 (Krt19) expression as a hallmark of corneal maturation. Next, we set out to identify a novel marker of murine corneal epithelial progenitor cells before, during and after maturation, and we found that Bmi1 is expressed in the basal epithelium of the central cornea and limbus. Furthermore, we demonstrated that Bmi1+ cells participated in tissue replenishment in the central cornea. These Bmi1+ cells did not maintain homeostasis of the cornea for more than 3 months, reflecting their status as progenitor rather than stem cells. Finally, after injury, Bmi1+ cells fueled homeostatic maintenance, whereas wound closure occurred via epithelial reorganization. Stem Cells 2018
Características citopatológicas del carcinoma de células acinares (CCA) de glándula salival: a propósito de cuatro observaciones
Objetivo: Presentar las características citopatológicas del carcinoma
acinar (CCA), así como su correlación cito-histológica,
comentando los problemas de diagnóstico diferencial de esta
entidad en base a cuatro observaciones estudiadas mediante
PAAF.
Casos clínicos: Dos varones de 52 y 53 años, una mujer de
79 años, y una niña de 12 años que presentaron tumoraciones
localizadas en territorio parotídeo (casos 1, 2 y 4), y a nivel
laterocervical (caso 3).
En tres pacientes, la PAAF fue, junto a los estudios de imagen,
la primera aproximación diagnóstica; correspondiendo el caso
3 a una punción de adenopatías laterocervicales metastásicas en
una paciente con antecedentes de CCA de parótida.
Hallazgos citológicos: Las extensiones citológicas mostraron
abundante celularidad tumoral dispuesta en pequeñas placas
monocapa, formando estructuras acinares, o como células aisladas.
Es de destacar la abundancia de núcleos desnudos en el
fondo de los frotis, y la ausencia de grasa y de epitelio ductal.
Las células poseían núcleos monomorfos redondeados u ovales,
nucleólo poco evidente y abundante citoplasma granular o
finamente vacuolado.
Discusión: La PAAF proporciona información esencial en la
actuación diagnóstico-terapeútica de las tumoraciones de la
glándula salival, resultando esta metodología muy sensible
en su eficacia diagnóstica. La identificación de los CCA frecuentemente
presenta dificultades, debido a la gran similitud citológica de las células tumorales con el componente acinar
normal propio de la glándula salival. El diagnóstico diferencial
se plantea, fundamentalmente, con carcinomas de células claras,
con carcinomas mucoepidermoides, con el tumor de Warthin
y con los oncocitomas. Nuestras observaciones confirman la
validez de la PAAF en una primera aproximación diagnóstica
de estas lesiones tumorales accesibles a la punción directa.Objective: To present the cytopathological characteristics of
acinic cell carcinoma (ACC) as well as its cyto-histological
correlation, commenting on the differential diagnostic problems
of this entity based on four observations studied using fine-needle
aspiration biopsy (FNAB).
Clinical Cases: Two males of 52 and 53 years of age, one 79
year-old woman and a girl of 12 years of age, who presented
tumors located in the parotid area (cases 1, 2 and 4) and at the
laterocervical level (case 3).
In 3 patients, the FNAB was, together with the image studies,
the first diagnostic indication; case 3 corresponding to a puncture
of metastatic laterocervical adenopathies in a patient with
a history of parotid ACC.
Cytological findings: The cytologic smears revealed abundant
tumoral cellularity arranged in small monolayered sheets,
forming acinar structures or isolated cells. The abundance of
bare nuclei at the background of the smears, and the absence of
adipose tissue and ductal epithelium are highlighted. The cells
possessed round or oval monomorphic nuclei, few nucleoli and
abundant granular or finely vacuolate cytoplasm.
Discussion: FNAB provides essential information on the diagnostic-
therapeutic management of salivary gland tumors; this
methodology is highly sensitive in its diagnostic efficacy. The
diagnosis of ACCs frequently presents difficulties, owing to
the great cytologic similarity of the tumor cells with the normal
acinar component of the salivary gland. The differential diag-nosis is considered, fundamentally, with clear cell carcinomas,
mucoepidermoid carcinomas, Warthin's tumor, and oncocytomas.
Our observations confirm the validity of FNAB in a first
diagnostic approximation for those lesions accessible to direct
puncture
Crystallization and preliminary X-ray diffraction analysis of the N-terminal domain of Paenibacillus barcinonensis xylanase 10C containing the CBM22-1-CBM22-2 tandem
A construct containing the CBM22-1-CBM22-2 tandem forming the N-terminal domain of Paenibacillus barcinonensis xylanase 10C (Xyn10C) has been purified and crystallized. A xylan-binding function and an affinity for mixed [beta]-1,3/[beta]-1,4 glucans have previously been demonstrated for some members of the CBM22 family. The sequence of the tandem is homologous to the N-terminal domains found in several thermophilic enzymes. Crystals of this tandem were grown by the streak-seeding method after a long optimization strategy. The structure has been determined by molecular replacement to a resolution of 2.43 Å and refinement is under way. This study represents the first structure containing two contiguous CBM22 modules, which will contribute to a better understanding of the role that this multiplicity plays in fine-tuning substrate affinit
Diagnóstico citológico de las recidivas tumorales de ameloblastoma: presentación de dos casos clínicos
Introducción: Los ameloblastomas son los tumores odontogénicos
más frecuentes del maxilar. A pesar de su aspecto citohistológico
de benignidad, se comportan como tumores invasivos,
recidivantes y con posibilidad de metastatizar.
La P.A.A.F. es una prueba rápida e incruenta que proporciona
un diagnóstico prequirúrgico evitando, en ocasiones, tomas
biópsicas destinadas al diagnóstico.
Presentamos las características citológicas de dos casos de
recidiva yugal de ameloblastoma de rama mandibular diagnosticados
por PAAF, así como su correlación citohistológica.
Casos clínicos: Dos pacientes, una mujer de 36 años y un varón
de 62 años, que acuden por tumoración mandibular de escasos
meses de evolución. En ambos casos, la primera aproximación
diagnóstica fue junto a los estudios radiológicos el estudio
histológico de la masa tumoral. Tras la extirpación terapeútica,
ambos casos recidivaron. El diagnóstico de las recidivas fue
establecido citológicamente mediante PAAF.
Las extensiones citológicas mostraron un fondo granular con
aislados macrófagos y células multinucleadas gigantes y una
abundante celularidad epitelial de aspecto basaloide dispuesta
en grupos cohesivos configurando imágenes de empalizada
periférica, así como pequeños grupos de células de metaplasia
escamosa.
Discusión: La PAAF se considera como un método diagnóstico rápido, incruento y fiable en el diagnóstico del ameloblastoma.
La citología de estos tumores revela los componentes de la lesión
que, en general, son suficientes para llegar al diagnóstico de
ameloblastoma, especialmente en casos de recidiva.Introduction: Ameloblastomas are the most frequent odontogenic
tumors of the maxilla. In spite of their benign cytohistological
appearance, they behave as invasive recurring tumors, with the
possibility of metastasis.
FNAB is a rapid, bloodless test that provides a pre-surgical
diagnosis, thus, on occasions avoiding the need for diagnostic
biopsies.
We present the cytological characteristics of two cases of jugal
recurrences of mandibular ameloblastomas diagnosed by FNAB,
as well as their cytohistological correlation.
Clinical cases: Two patients, a 36-year-old woman, and a 62-
year-old male who both attended with mandibular swelling
of a few months evolution. In both cases the first diagnostic
approximation was the histological study of the tumoral mass,
together with the radiological studies. Following therapeutic
extirpation both cases recurred. The diagnosis of the recurrences
was established cytologically by means of FNAB.
The cytologic smears revealed a granular background with isolated
macrophages and giant multinucleate cells and an abundant
epithelial cellularity of basaloid appearance arranged in cohesive
groups forming images of peripheral palidasing, as well as small
groups of squamous metaplastic cells.
Discussion: FNAB is considered to be a rapid, bloodless and reliable
method for the diagnosis of ameloblastoma. The cytology of these tumors reveals components of the lesion that, in general,
are sufficient for the diagnosis of ameloblastoma, especially in
cases of recurrence
A computerized analysis of the entire retinal ganglion cell population and its spatial distribution in adult rats
AbstractIn adult albino (SD) and pigmented (PVG) rats the entire population of retinal ganglion cells (RGCs) was quantified and their spatial distribution analyzed using a computerized technique. RGCs were back-labelled from the optic nerves (ON) or the superior colliculi (SCi) with Fluorogold (FG). Numbers of RGCs labelled from the ON [SD: 82,818±3,949, n=27; PVG: 89,241±3,576, n=6) were comparable to those labelled from the SCi [SD: 81,486±4,340, n=37; PVG: 87,229±3,199; n=59]. Detailed methodology to provide cell density information at small scales demonstrated the presence of a horizontal region in the dorsal retina with highest densities, resembling a visual streak
An optimal filter for the detection of galaxy clusters through weak lensing
We construct a linear filter optimised for detecting dark-matter halos in
weak-lensing data. The filter assumes a mean radial profile of the halo shear
pattern and modifies that shape by the noise power spectrum. Aiming at
separating dark-matter halos from spurious peaks caused by large-scale
structure lensing, we model the noise as being composed of weak lensing by
large-scale structures and Poisson noise from random galaxy positions and
intrinsic ellipticities. Optimal filtering against the noise requires the
optimal filter scale to be smaller than typical halo sizes. Although a perfect
separation of halos from spurious large-scale structure peaks is strictly
impossible, we use numerical simulations to demonstrate that our filter
produces substantially more sensitive, reliable and stable results than the
conventionally used aperture-mass statistic.Comment: 9 pages, 6 figures, A&A submitte
Ti(III) Catalysts for CO2/Epoxide Copolymerization at Unusual Ambient Pressure Conditions
Titanium compounds in low oxidation states are highly reducing species and hence powerful tools for the functionalization of small molecules. However, their potential has not yet been fully realized because harnessing these highly reactive complexes for productive reactivity is generally challenging. Advancing this field, herein we provide a detailed route for the formation of titanium(III) orthophenylendiamido (PDA) species using [LiBHEt3] as a reducing agent. Initially, the corresponding lithium PDA compounds [Li2(ArPDA)(thf)3] (Ar = 2,4,6-trimethylphenyl (MesPDA), 2,6-diisopropylphenyl (iPrPDA)) are combined with [TiCl4(thf)2] to form the heterobimetallic complexes [{TiCl(ArPDA)}(?-ArPDA){Li(thf)n}] (n = 1, Ar = iPr 3 and n = 2, Ar = Mes 4). Compound 4 evolves to species [Ti(MesPDA)2] (6) via thermal treatment. In contrast, the transformation of 3 into [Ti(iPrPDA)2] (5) only occurs in the presence of [LiNMe2], through a lithium-assisted process, as revealed by density functional theory (DFT). Finally, the Ti(IV) compounds 3?6 react with [LiBHEt3] to give rise to the Ti(III) species [Li(thf)4][Ti(ArPDA)2] (Ar = iPr 8, Mes 9). These low-valent compounds in combination with [PPN]Cl (PPN = bis(triphenylphosphine)iminium) are proved to be highly selective catalysts for the copolymerization of CO2 and cyclohexene epoxide. Reactions occur at 1 bar pressure with activity/selectivity levels similar to Salen? Cr(III) compounds.Comunidad de MadridUniversidad de AlcaláPrograma Estímulo a la Investigación de Jóvenes Investigadore
Constraints on the inner density profile of dark-matter haloes from weak gravitational lensing
We construct two linear filtering techniques based on weak gravitational
lensing to constrain the inner slope of the density profile of
dark-matter halos. Both methods combine all available information into an
estimate of this single number. Under idealised assumptions, is
constrained to ~15% if the halo concentration c is known, and to < 30% if not.
We argue that the inevitable degeneracy between density-profile slope and halo
concentration cannot be lifted under realistic conditions, and show by means of
Fisher-matrix methods which linear combination of and c is best
constrained by our filtering of lensing data. This defines a new parameter,
called P1, which is then constrained to ~15% for a single massive halo. If the
signals of many halos can be stacked, their density profiles should thus be
well constrained by the linear filters proposed here with the advantagebe
insensitive to the cluster substructures.Comment: 11 pages, 13 figures, Accepted MNRA
Hydrolase–like catalysis and structural resolution of natural products by a metal–organic framework
The exact chemical structure of non–crystallising natural products is still one of the main challenges in Natural Sciences. Despite tremendous advances in total synthesis, the absolute structural determination of a myriad of natural products with very sensitive chemical functionalities remains undone. Here, we show that a metal–organic framework (MOF) with alcohol–containing arms and adsorbed water, enables selective hydrolysis of glycosyl bonds, supramolecular order with the so–formed chiral fragments and absolute determination of the organic structure by single–crystal X–ray crystallography in a single operation. This combined strategy based on a biomimetic, cheap, robust and multigram available solid catalyst opens the door to determine the absolute configuration of ketal compounds regardless degradation sensitiveness, and also to design extremely–mild metal–free solid–catalysed processes without formal acid protons.This work was supported by the Ministero dell’Istruzione, dell’Università e della Ricerca
(Italy) and the MINECO (Spain) (Projects CTQ2016-75671-P, CTQ 2017-86735-P,
RTC-2017-6331-5, Severo Ochoa program SEV-2016-0683 and Excellence Unit “Maria
de Maeztu” MDM-2015-0538). R.B. thanks the MIUR (Project PON R&I FSE-FESR
2014–2020) for grant. L.B wishes to thank Italian MIUR for grant n. AIM1899391–1 in
the framework of the project “Azione I.2, Mobilità dei Ricercatori, PON R&I 2014–2020”.
Thanks are also extended to the “2019 Post-doctoral Junior Leader-Retaining Fellowship,
la Caixa Foundation (ID100010434 and fellowship code LCF/BQ/PR19/11700011” (J. F.-
S.). S. S.-N. thanks ITQ for the concession of a contract. D.A. acknowledges the financial
support of the Fondazione CARIPLO/“Economia Circolare: ricerca per un futuro sostenibile”
2019, Project code: 2019–2090, MOCA. E.P. acknowledges the financial support
of the European Research Council under the European Union’s Horizon 2020 research
and innovation program/ERC Grant Agreement No. 814804, MOF-reactors
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