30 research outputs found
A direct anatomical study of additional renal arteries in a Colombian mestizo population
Traditional anatomy describes each kidney as receiving irrigation from a single
renal artery. However, current literature reports great variability in renal blood
supply, the number of renal arteries mentioned being the most frequently found
variation. Such variation has great implications when surgery is indicated, such
as in renal transplants, uroradiological procedures, renovascular hypertension,
renal trauma and hydronephrosis. This article pretends to determine the frequency
of additional renal arteries and their morphological expression in
Colombian population in a cross-sectional study. A total of 196 of renal blocks
were analysed from autopsies carried out in the Bucaramanga Institute of
Forensic Medicine, Colombia; these renal blocks were processed by the injection-
corrosion technique. The average age of the people being studied was
33.8 ± 15.6 years; 85.4% of them were male and the rest female. An additional
renal artery was found in 22.3% of the whole population and two additional
ones were found in 2.6% of the same sample. The additional renal artery was
most frequently found on the left side. The additional artery arose from the
aorta’s lateral aspect (52.4%); these additional arteries usually entered the renal
parenchyma through the hilum. No difference was established according to gender.
Nearly a third of the Colombian population presents one additional renal
artery and about 3% of the same population presents two additional renal arteries.
Most of them reached the kidney through its hilar region. (Folia Morphol
2008; 67: 129–13
25th-order high-temperature expansion results for three-dimensional Ising-like systems on the simple cubic lattice
25th-order high-temperature series are computed for a general
nearest-neighbor three-dimensional Ising model with arbitrary potential on the
simple cubic lattice. In particular, we consider three improved potentials
characterized by suppressed leading scaling corrections. Critical exponents are
extracted from high-temperature series specialized to improved potentials,
obtaining , , ,
, , . Moreover, biased
analyses of the 25th-order series of the standard Ising model provide the
estimate for the exponent associated with the leading scaling
corrections. By the same technique, we study the small-magnetization expansion
of the Helmholtz free energy. The results are then applied to the construction
of parametric representations of the critical equation of state, using a
systematic approach based on a global stationarity condition. Accurate
estimates of several universal amplitude ratios are also presented.Comment: 40 pages, 15 figure
Development of a versatile laboratory experiment to teach the metabolic transformation of hydrolysis
In this paper we describe an easy, reliable, versatile and inexpensive laboratory experiment to teach the metabolic transformation of hydrolysis to Pharmacy students. The experiment does not require the sacrifice of any experimental animal, or any work with organs or tissues, and so can be implemented in a typical university chemistry laboratory. We used acetylsalicylic acid (ASA), hexyl salicylate (HS) and two enzymes, a lipase and an esterase. Since both ASS and HS liberate salicylic acid (SA) upon hydrolysis, students can evaluate the different enzymatic transformations by monitoring the amount of SA liberated. The learning outcomes are an enhanced student understanding of: (1) the process of hydrolysis; (2) the application of enzymatic transformations of molecules from food to xenobiotics; (3) the differences between the general specificity of substrate of both enzymes; (4) the concepts of the lipophilic pocket; (5) the catalytic triad and its regioselectivity in relation to the ester bond. A questionnaire was administered to participating students at three points in time: at the beginning of the module, after enzymatic hydrolysis was taught in class, and after the laboratory experiment. From an analysis of the questionnaire data we conclude that this practical helped Pharmacy students to understand these concepts
The Physics of Star Cluster Formation and Evolution
© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe
Taming the terminological tempest in invasion science
Standardised terminology in science is important for clarity of interpretation and communication. In invasion science â a dynamic and rapidly evolving discipline â the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions. A standardised framework is therefore needed for a clear, universally applicable, and consistent terminology to promote more effective communication across researchers, stakeholders, and policymakers. Inconsistencies in terminology stem from the exponential increase in scientific publications on the patterns and processes of biological invasions authored by experts from various disciplines and countries since the 1990s, as well as publications by legislators and policymakers focusing on practical applications, regulations, and management of resources. Aligning and standardising terminology across stakeholders remains a challenge in invasion science. Here, we review and evaluate the multiple terms used in invasion science (e.g. ânon-nativeâ, âalienâ, âinvasiveâ or âinvaderâ, âexoticâ, ânon-indigenousâ, ânaturalisedâ, âpestâ) to propose a more simplified and standardised terminology. The streamlined framework we propose and translate into 28 other languages is based on the terms (i) ânon-nativeâ, denoting species transported beyond their natural biogeographic range, (ii) âestablished non-nativeâ, i.e. those non-native species that have established self-sustaining populations in their new location(s) in the wild, and (iii) âinvasive non-nativeâ â populations of established non-native species that have recently spread or are spreading rapidly in their invaded range actively or passively with or without human mediation. We also highlight the importance of conceptualising âspreadâ for classifying invasiveness and âimpactâ for management. Finally, we propose a protocol for classifying populations based on (i) dispersal mechanism, (ii) species origin, (iii) population status, and (iv) impact. Collectively and without introducing new terminology, the framework that we present aims to facilitate effective communication and collaboration in invasion science and management of non-native species
The impact on retrieval effectiveness of skewed frequency distributions
We present an analysis of word senses that provides a fresh insight
into the impact of word ambiguity on retrieval effectiveness with
potential broader implications for other processes of information
retrieval. Using a methodology of forming artificially ambiguous,
words known as pseudo-words, and through reference to other
researchersâ work, the analysis illustrates that the distribution of
the frequency of occurrence of the senses of a word plays a strong
role in ambiguityâs impact on effectiveness. Further investigation
shows that this analysis may also be applicable to other processes
of retrieval, such as Cross Language Information Retrieval, query
expansion, retrieval of OCRâed texts, and stemming. The analysis
appears to provide a means of explaining, at least in part, reasons
for the processesâ impact (or lack of it) on effectiveness
The local microenvironment drives activation of neutrophils in human brain tumors.
Neutrophils are abundant immune cells in the circulation and frequently infiltrate tumors in substantial numbers. However, their precise functions in different cancer types remain incompletely understood, including in the brain microenvironment. We therefore investigated neutrophils in tumor tissue of glioma and brain metastasis patients, with matched peripheral blood, and herein describe the first in-depth analysis of neutrophil phenotypes and functions in these tissues. Orthogonal profiling strategies in humans and mice revealed that brain tumor-associated neutrophils (TANs) differ significantly from blood neutrophils and have a prolonged lifespan and immune-suppressive and pro-angiogenic capacity. TANs exhibit a distinct inflammatory signature, driven by a combination of soluble inflammatory mediators including tumor necrosis factor alpha (TNF-É) and Ceruloplasmin, which is more pronounced in TANs from brain metastasis versus glioma. Myeloid cells, including tumor-associated macrophages, emerge at the core of this network of pro-inflammatory mediators, supporting the concept of a critical myeloid niche regulating overall immune suppression in human brain tumors
Identification of different subtypes of auditory neuropathy using electrocochleography
Currently, the physiological mechanisms underlying auditory neuropathy are unclear, and there are likely to be multiple sites of lesion. A better understanding of the disruption in individual cases may lead to more effective management and device selection. Frequency-specifi c round-window electrocochleography (ECochG) waveforms were used to assess local hair cell, dendritic, and axonal currents generated within the cochlea in 15 subjects with auditory neuropathy (16 ears). These results were compared with electrically evoked auditory brainstem response (EABR) measured after cochlear implantation. The results of this study demonstrate that predominantly two patterns of ECochG waveforms can be identifi ed: (i) a prolonged latency of the hair cell summating potential (SP) waveform with or without residual CAP activity and (ii) a normal latency SP, typically followed by a dendritic potential (DP). We show that seven of eight subjects with a prolonged SP showed a normal EABR waveform, consistent with a presynaptic lesion, whereas six of seven subjects with a normal latency SP showed poor morphology or absent EABR waveforms, consistent with a postsynaptic lesion. We suggest that a presynaptic and postsynaptic type of auditory neuropathy exist, which may have implications for the fi tting of cochlear implants.16 page(s