120 research outputs found
Photon Wave-packet Manipulation via Dynamic Electromagnetically Induced Transparency in Multilayer Structures
We present a Maxwell-Bloch description of the dynamics of a light pulse
propagating through a spatially inhomogeneous system consisting of alternating
layers of EIT media and vacuum. We study the effect of a dynamical modulation
of the EIT control field on the shape of the wave packet: interesting effects
due to the presence of interfaces with group velocity mismatch are found. An
effective description based on a continuity equation is developed. Modulation
schemes that can be realized in ultracold atomic samples with standard
experimental techniques are proposed and discussed
Energy performance and climate control in mechanically ventilated greenhouses: A dynamic modelling-based assessment and investigation
Controlled environment agriculture in greenhouse is a promising solution for meeting the increasing food demand of world population. The accurate control of the indoor environmental conditions proper of greenhouses enhances high crop productivity but, contemporarily, it entails considerable energy consumption due to the adoption of mechanical systems. This work presents a new modelling approach for estimating the energy consumption for climate control of mechanically ventilated greenhouses. The novelty of the proposed energy model lies in its integrated approach in simulating the greenhouse dynamics, considering the dynamic thermal and hygric behaviour of the building and the dynamic response of the cultivated crops to the variation of the solar radiation. The presented model simulates the operation of the systems and the energy performance, considering also the variable angular speed fans that are a new promising energy-efficient technology for this productive sector. The main outputs of the model are the hourly thermal and electrical energy use for climate control and the main indoor environmental conditions. The presented modelling approach was validated against a dataset acquired in a case study of a new fully mechanically controlled greenhouse during a long-term monitoring campaign. The present work contributes to increase the knowledge about the dynamics and the energy consumption of greenhouses, and it can be a valuable decision support tool for industry, farmers, and researchers to properly address an energy efficiency optimisation in mechanically ventilated greenhouses to reach the overall objective of decreasing the rising energy consumption of the agricultural sector
Observation of coherent many-body Rabi oscillations
A two-level quantum system coherently driven by a resonant electromagnetic
field oscillates sinusoidally between the two levels at frequency
which is proportional to the field amplitude [1]. This phenomenon, known as the
Rabi oscillation, has been at the heart of atomic, molecular and optical
physics since the seminal work of its namesake and coauthors [2]. Notably, Rabi
oscillations in isolated single atoms or dilute gases form the basis for
metrological applications such as atomic clocks and precision measurements of
physical constants [3]. Both inhomogeneous distribution of coupling strength to
the field and interactions between individual atoms reduce the visibility of
the oscillation and may even suppress it completely. A remarkable
transformation takes place in the limit where only a single excitation can be
present in the sample due to either initial conditions or atomic interactions:
there arises a collective, many-body Rabi oscillation at a frequency
involving all N >> 1 atoms in the sample [4]. This is true even
for inhomogeneous atom-field coupling distributions, where single-atom Rabi
oscillations may be invisible. When one of the two levels is a strongly
interacting Rydberg level, many-body Rabi oscillations emerge as a consequence
of the Rydberg excitation blockade. Lukin and coauthors outlined an approach to
quantum information processing based on this effect [5]. Here we report initial
observations of coherent many-body Rabi oscillations between the ground level
and a Rydberg level using several hundred cold rubidium atoms. The strongly
pronounced oscillations indicate a nearly complete excitation blockade of the
entire mesoscopic ensemble by a single excited atom. The results pave the way
towards quantum computation and simulation using ensembles of atoms
Acoustic multi-detection of Gliadin using QCM crystals patterned with controlled sectors of tem grid and annealed Nanoislands on gold electrode
Celiac diseases are a group of gluten ingestion-correlated pathologies that are widespread and, in some cases, very dangerous for human health. The only effective treatment is the elimination of gluten from the diet throughout life. Nowadays, the food industries are very interested in cheap, easy-to-handle methods for detecting gluten in food, in order to provide their consumers with safe and high-quality food. Here, for the first time, the manufacture of controlled micropatterns of annealed gold nanoislands (AuNIs) on a single QCM crystal (QCM-color) and their biofunctionalization for the specific detection of traces of gliadin is reported. In addition, the modified quartz crystal with a TEM grid and 30 nm Au (Q-TEM grid crystal) is proposed as an acoustic sensitive biosensing platform for the rapid screening of the gliadin content in real food products
Quartz crystal microbalance genosensing of brettanomyces bruxellensis yeast in wine using a rapid and efficient drop and collect protocol
A miniaturized quartz crystal microbalance (QCM) genosensor is proposed for sensitive and real-time detection of short ssDNA sequences (53 bp) or DNA extracted from Brettanomyces bruxellensis (Brett) yeast cells. The presence of Brett yeast causes a depreciation of the quality of aged fine wines, producing molecules of unpleasant odors and biogenic amines that are harmful to human health. More specifically, standard quartz crystal (S-QCM) and homemade 4 nm gold transmission electron microscopy (TEM)-grid patterned quartz (multi-TEM QCM) are herein proposed for biofunctionalization steps with different ssDNA sequences. By employing a rapid and efficient drop and collect protocol, the specific detection of 1 pg/\ub5L ssDNA Brett of a short sequence and 100 ng/\ub5L DNA of B. bruxellensis extracted from a wine sample (VR2008) is reported
Optical properties of atomic Mott insulators: from slow light to dynamical Casimir effects
We theoretically study the optical properties of a gas of ultracold,
coherently dressed three-level atoms in a Mott insulator phase of an optical
lattice. The vacuum state, the band dispersion and the absorption spectrum of
the polariton field can be controlled in real time by varying the amplitude and
the frequency of the dressing beam. In the weak dressing regime, the system
shows unique ultra-slow light propagation properties without absorption. In the
presence of a fast time modulation of the dressing amplitude, we predict a
significant emission of photon pairs by parametric amplification of the
polaritonic zero-point fluctuations. Quantitative considerations on the
experimental observability of such a dynamical Casimir effect are presented for
the most promising atomic species and level schemes
Criação de insetos para pesquisa sobre controle biológico: Bactrocera carambolae e Fopius arisanus.
A mosca-da-carambola (Bactrocera carambolae) é uma praga quarentenária presente no Brasil, restrita aos estados do Amapá, Roraima e Pará. A Embrapa vem estudando diferentes formas de controle químico e biológico para essa praga. Para realização dos experimentos é necessária a obtenção de diferentes fases de desenvolvimento da praga e elevado número de indivíduos, determinação do índice de infestação, percentual de parasitismo e razão sexual. Desde 2013, a Embrapa Amapá mantém uma criação de B. carambolae e a partir de 2015, do seu inimigo natural Fopius arisanus, para realização de pesquisas sobre o controle biológico. O objetivo deste trabalho foi avaliar se as colônias de B. carambolae e de Fopius arisanus, mantidas na Embrapa Amapá, estão bem adaptadas às condições laboratoriais
Eficiência de dieta larval à base de cenoura para criação de Bactrocera carambolae em laboratório.
A criação de Bactrocera carambolae Drew & Hancock em laboratório é fundamental para o desenvolvimento de estudos bioecológicos e de controle dessa espécie. Buscando otimizar a criação em laboratório avaliou-se a eficiência da dieta larval à base de cenoura, em comparação a dieta larval à base de bagaço de cana no Laboratório de Entomologia da Embrapa Amapá, Macapá/AP. O estudo foi realizado em dois ensaios com cinco repetições. Cada repetição foi composta por um recipiente com dieta e 100 ovos de B. carambolae. Em gaiolas de criação de B. carambolae (30 dias de idade) foram disponibilizados dispositivos artificiais de oviposição expostos por três horas para obtenção dos ovos. No dia 07/02/2018, os recipientes contendo a dieta à base de bagaço de cana foram acondicionados em bandejas de plástico contendo vermiculita
Biologia de Bactrocera carambolae Drew & Hancock, 1994: duração do período embrionário em laboratório.
Value of a Multidisciplinary Approach in Sinonasal Inverted Papilloma with Extensive Ossification
Objective: Background: Casa Report: Conclusions: Rare disease Inverted papilloma is a benign epithelial lesion of the nasal cavities. Although commonly encountered in clinical practice, it rarely presents with extensive ossification and few cases have been described in the literature. Herein, we describe the case of a 51-year-old man who presented to clinical attention for persistent right nasal obstruction. Magnetic resonance imaging (MRI) and computed tomography (CT) scans of the facial bones showed a lobated lesion with ossification occupying most of the right nasal cavity. The lesion was removed by endoscopic sinus surgery, leaving the surrounding bone structures intact. On pathological examination, mature bone tissue was found within an inverted papilloma. The pathologist contacted the surgeon, who confirmed that no healthy bone tissue was removed during the procedure. Therefore, a diagnosis of inverted papilloma with ossification could be made without the use of ancillary techniques. Inverted papilloma with ossification is a common lesion with a rare feature. Our report investigates the diagnostic difficulties of a paradigmatic case, highlighting the importance of multidisciplinary teamwork in reach-ing the final diagnosis
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