1,134 research outputs found
Parâmetros de consistência dos solos: seu estudo e avaliação ao longo de perfis pedológicos para aplicação na engenharia rodoviária.
Foram estudados os limites de consistencia dos solos ao longo de perfis pedologicos para aplicacao na engenharia rodoviaria. As amostras foram coletadas de horizontes superficiais e subsuperficiais em dez perfis de diferentes classes de solos. As analises das amostras foram efetuadas em laboratorio seguindo a rotina usada em pedologia. Foram determinados tambem, para cada horizonte considerado, os limites de liquidez(LL), plasticidade(LP) e contracao(LC); o indice de plasticidade(IP), e o grau de contracao(GC). A analise dos dados de laboratorio, aliada as observacoes de campo, demonstrou haver uma correlacao empirica, entre as razoes "% de argila/IP" ou "IP//% de argila" e as propriedades dos solos considerados quanto a conservacao das estradas, no caso dossolos com mais de 35% de argila no horizonte B. Essas relacoes poderiam funcionar como indicadores das qualidades desses solos para a implantacao de rodovias. Obteve-se tambem uma certa evidencia neste sentido, para esses mesmos solos, atraves de graficos elaborados para cada perfil.bitstream/item/62536/1/CNPS-BOL.-PESQ.-13-82.pd
Synthesis, Photochemical, and Redox Properties of Gold(I) and Gold(III) Pincer Complexes Incorporating a 2,2′:6′,2″-Terpyridine Ligand Framework
Reaction of [Au(C6F5)(tht)] (tht = tetrahydrothiophene) with 2,2′:6′,2″-terpyridine (terpy) leads to complex [Au(C6F5)(η1-terpy)] (1). The chemical oxidation of complex (1) with 2 equiv of [N(C6H4Br-4)3](PF6) or using electrosynthetic techniques affords the Au(III) complex [Au(C6F5)(η3-terpy)](PF6)2 (2). The X-ray diffraction study of complex 2 reveals that the terpyridine acts as tridentate chelate ligand, which leads to a slightly distorted square-planar geometry. Complex 1 displays fluorescence in the solid state at 77 K due to a metal (gold) to ligand (terpy) charge transfer transition, whereas complex 2 displays fluorescence in acetonitrile due to excimer or exciplex formation. Time-dependent density functional theory calculations match the experimental absorption spectra of the synthesized complexes. In order to further probe the frontier orbitals of both complexes and study their redox behavior, each compound was separately characterized using cyclic voltammetry. The bulk electrolysis of a solution of complex 1 was analyzed by spectroscopic methods confirming the electrochemical synthesis of complex 2
Low-cost test measurement setup for real IoT BLE sensor device characterization
The methodology presented in this paper aims to characterize impairments shown by real devices which are usually neglected on standardized tests but that become very important in massive IoT scenarios. For instance, we have measured that real BLE scanners are not able to scan continuously even though they are configured to do so. Besides, we have also found and demonstrated that some manufacturers seem not to apply any backoff mechanism although it is mandatory. These two unexpected behaviors have a significant impact on the performance of massive wireless sensor networks based on BLE. So, it becomes necessary to characterize these and other impairments. The proposed tests are based on device current consumption measurements and their association with the information obtained from upper layers. We describe a new low-cost generic measurement setup and provide all the necessary data (configuration parameters, scripts, etc.) for applying the proposed methodology. As an example, we use it to profile the behavior of Bluetooth Low Energy devices. Furthermore, the proposed setup can also inspire researchers to characterize other wireless technology devices, like Wi-Fi, Zigbee, LoRa, etc
Infected Vertebroplasty Due to Uncommon Bacteria Solved Surgically: A Rare and Threatening Life Complication of a Common Procedure
Case report. OBJECTIVE: The aim of this work is to describe a case
of infected vertebroplasty due to uncommon bacteria solved surgically with 2
years of follow-up and to discuss 6 other cases found in literature. SUMMARY OF
BACKGROUND DATA: Vertebroplasty is a well-known and useful technique for the
treatment of painful osteoporotic vertebral fractures. Complications, such as
cord or root compression or pulmonary embolisms, are infrequent and are mainly
related with the frequent escape of cement throughout the vertebral veins.
Infection is even more rare, but when it occurs is difficult to manage and can be
a life-threatening complication. METHODS: A 63-year-old-man had a spondylitis of
L2 after vertebroplasty. The patient was initially managed with antibiotics
without clinical improvement. Surgical treatment by anterior debridement and
anterior and posterior stabilization was done. The bacteria isolated from the
intraoperative cultures were Serratia marcescens, Stenotrophomonas maltophilia,
and Burkholderia cepacia. After surgery, the patient was treated with antibiotics
for 3 month. RESULTS: After 2 years of follow-up, the patient was free of pain,
without signs of infection, and a correct fusion was achieved. CONCLUSION: When
facing an infected vertebroplasty, initial conservative treatment with needle
biopsy culture and antibiotic administration are a rational option to start. If
this treatment fails, surgical debridement is then indicated in order to remove
the infected tissue and the acrylic cement and to stabilize the spine. Although
this can be an effective treatment, it could be a difficult and hazardous
surgical procedure
Exclusive measurement of coherent eta photoproduction from the deuteron
Coherent photoproduction of eta mesons from the deuteron has been measured
from threshold up to incident photon energies of 750 MeV using the photon
spectrometer TAPS at the tagged photon facility at the Mainz microtron MAMI.
For the first time, differential coherent cross sections have been deduced from
the coincident detection of the eta meson and the recoil deuteron. A missing
energy analysis was used for the suppression of background events so that a
very clean identification of coherent eta-photoproduction was achieved. The
resulting cross sections agree with previous experimental results except for
angles around 90 deg in the photon-deuteron cm-system where they are smaller.
They are compared to various model calculations.Comment: 4 pages, 4 figure
5G Radio Resource Allocation for Communication and Computation Offloading
Edge computing is envisioned as a key enabler in future cellular networks by bringing the computing, networking and storage resources closer to the end users and enabling offloading for computation-intensive or latency-critical tasks coming from the emerging 5G/6G applications. Such technology also introduces additional challenges when it comes to deciding when to offload or not since the dynamic wireless environment plays a significant role in the overall communication and computation costs when offloading workload to the nearby edge nodes. In this paper, we focus on the communication cost in computation offloading via wireless channels, by formulating an α -fair utility-based radio resource allocation (RRA) problem tailored for offloading in a multi-user urban scenario where the uplink connection is the main focus. We begin by modeling the wireless channel with large- and small-scale fading at both lower and millimetre-wave frequencies, followed by data rate calculation based on 3GPP for a more realistic approach. Then, while assessing the fairness of the RRA, we simulate the resource allocation framework while taking into account both users who need to offload and users who are only interested in high downlink data rates. Simulation results show that the weighted proportional fairness method adapted for computation offloading can provide a good trade-off between fairness and performance compared to other benchmark schemes
Neutron polarizabilities investigated by quasi-free Compton scattering from the deuteron
Measuring Compton scattered photons and recoil neutrons in coincidence,
quasi-free Compton scattering by the neutron has been investigated at MAMI
(Mainz) at in an energy range from 200 to 400 MeV.
From the data a polarizability difference of in units of has been
determined. In combination with the polarizability sum deduced from photo absorption data, the neutron electric and
magnetic polarizabilities, and ,
are obtained
Quasi-free Compton Scattering and the Polarizabilities of the Neutron
Differential cross sections for quasi-free Compton scattering from the proton
and neutron bound in the deuteron have been measured using the Glasgow/Mainz
tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48
cm 64 cm NaI(Tl) photon detector and the G\"ottingen SENECA
recoil detector. The data cover photon energies ranging from 200 MeV to 400 MeV
at . Liquid deuterium and hydrogen targets
allowed direct comparison of free and quasi-free scattering from the proton.
The neutron detection efficiency of the SENECA detector was measured via the
reaction . The "free" proton Compton scattering cross
sections extracted from the bound proton data are in reasonable agreement with
those for the free proton which gives confidence in the method to extract the
differential cross section for free scattering from quasi-free data.
Differential cross sections on the free neutron have been extracted and the
difference of the electromagnetic polarizabilities of the neutron have been
obtained to be
in units . In combination with the polarizability sum deduced from photoabsorption data, the neutron electric and
magnetic polarizabilities, and
are obtained. The backward spin polarizability of the neutron was determined to
be
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