Susceptibility Spectrum Research Articles

Pattern of antimicrobial sensitivity in Enterococcus in case of urinary tract infection, 5 years experiences in a tertiary care hospital

Introduction: Urinary tract infection is very common in our community mostly in females and enterococcal infection is very frequent. There is gradual development of resistance against this organism thus narrowing the spectrum of susceptibility. Aims: So, the aim of this study to detect the spectrum of sensitivity pattern in case of enterococcus in case of urinary tract infection. Materials and Methods: In this retrospective cross sectional study, morning midstream clean-catch urine form total 1550 symptomatic patients was studied for the spectrum of antibiotic susceptibility according to Clinical & laboratory Standard Institute (CLSI) guideline. Results: Total 189 patients were infected with enterococci. They showed sensitivity to Vancomycin (87.83%), Teicoplanin (85.18%), Lenazolid (84.12%) and nitrofurantoin (74.07%), and moderate degree of sensitivity in piperacillin-tazobactam (67.19%), imipenem (64.60%) and gentamicin (46.56%) and Amoxycillin-clavulanic acid (54.49%). Conclusion: Proper antibiotic-stewardship is ultimate requirement to prevent the development of bacterial resistance. So, regular surveillance as well as monitoring is very much necessary to update the knowledge about the susceptibility pattern of urinary pathogens which will guide the therapy. Keyword: Enterococcus, Symptomatic urinary tract infections, Culture and sensitivity, Tertiary medical centre

Candidaemia in a Tertiary Care Centre of Developing Country: Monitoring Possible Change in Spectrum of Agents and Antifungal Susceptibility

AbstractPurpose: Candidaemia is a major cause of morbidity and mortality of hospitalised patients, especially in developing countries. This study was conducted to monitor any change in species distribution and antifungal susceptibility pattern of Candida species causing candidaemia over the last 20 years. Materials and Methods: The candidaemia cases reported during January 1999 and December 2018 at our centre were reviewed. The yeasts were identified by phenotypic characters (during 1999–2014) and matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) (during 2014–2018). Antifungal susceptibility testing (AFST) was performed in accordance with the Clinical and Laboratory Standards Institute guidelines. Results: A total of 602,963 blood samples from patients with suspected sepsis were processed. Candidaemia was diagnosed in 7927 (1.31%) cases. The frequency of cases rose significantly (P = 0.000) in the last quarter of the study. Candida tropicalis (40.1%) was the most common species, followed by Candida albicans (15.2%), Wickerhamomyces anomalus (13.1%), Candida krusei (6.6%), Candida parapsilosis (4.7%) and others. Rare species such as Candida auris, Candida lambica, Candida orthopsilosis, Candida vishwanathii were identified after the introduction of MALDI-TOF. The minimum inhibitory concentrations of amphotericin B rose significantly from the first to last quarter (0.5%–4.9%). Fluconazole resistance was fairly constant at 7.4%–8.8%. Conclusion: Local epidemiology of candidaemia at our centre was distinct regarding prevalence and change of spectrum of species. The identification of rare species was possible after the introduction of MALDI-TOF. With the emergence of multidrug-resistant C. auris and resistance in other species, routine AFST has become imperative.

Single-particle versus collective effects in assemblies of nanomagnets: Screening

We discuss experimentally realizable situations in which surface effects may “screen out” the dipolar interactions in an assembly of nanomagnets, which then seemingly behaves as a noninteracting system. To illustrate this screening effect we consider three examples of physical observables, equilibrium magnetization, ac susceptibility and ferromagnetic resonance spectrum. For this purpose, we summarize our formalism that accounts for both the intrinsic features of the nanomagnets and their collective effects within an assembly and establish the conditions for screening.

Acute air pollution exposure alters neutrophils in never-smokers and at-risk humans.

Outdoor air pollution exposure increases chronic obstructive pulmonary disease (COPD) hospitalisations, and may contribute to COPD development. The mechanisms of harm, and the extent to which at-risk populations are more susceptible are not fully understood. Neutrophils are recruited to the lung following diesel exhaust exposure, a model of traffic-related air pollution (TRAP), but their functional role in this response is unknown. The purpose of this controlled human-exposure crossover study was to assess the effects of acute diesel exhaust exposure on neutrophil function in never-smokers and at-risk populations, with support from additional in vitro studies.18 participants, including never-smokers (n=7), ex-smokers (n=4) and mild-moderate COPD patients (n=7), were exposed to diesel exhaust and filtered air for 2 h on separate occasions, and neutrophil function in blood (0 h and 24 h post-exposure) and bronchoalveolar lavage (24 h post-exposure) was assessed.Compared to filtered air, diesel exhaust exposure reduced the proportion of circulating band cells at 0 h, which was exaggerated in COPD patients. Diesel exhaust exposure increased the amount of neutrophil extracellular traps (NETs) in the lung across participants. COPD patients had increased peripheral neutrophil activation following diesel exhaust exposure. In vitro, suspended diesel exhaust particles increased the amount of NETs measured in isolated neutrophils. We propose NET formation as a possible mechanism through which TRAP exposure affects airway pathophysiology. In addition, COPD patients may be more prone to an activated inflammatory state following exposure.This is the first controlled human TRAP exposure study directly comparing at-risk phenotypes (COPD and ex-smokers) with lower-risk (never-smokers) participants, elucidating the human susceptibility spectrum.

Magnetic Susceptibility of Ferromagnetic Alloy Material Co (1-x) Ni (x) Nanocube and Nanosphere Models

A hard disk is a data storage medium composed of a thin layer of magnetic material. Hard drives take advantage of the characteristics of magnetic materials that are stable to heat and have sensitivity to magnetic fields. One of the best materials to use a thin layer ferromagnetic on a hard disk is CoNi alloy. Hard drives with larger storage capacities require magnetic materials with high magnetic susceptibility values and Curie temperatures to obtain the best magnetic properties. The magnetic susceptibility of alloy ferromagnetic material Co (1- x) Ni (x) nanocube and nanosphere is calculated using vampire-based micro magnetic simulation. The research was conducted using a literature review on the parameters of the CoNi alloy material, and then it was simulated in the vampire program. The data generated from the simulation are magnetic susceptibility (1/tesla) and temperature (K). The spectrum of the magnetic susceptibility graph that shifts to the right as the Ni (x) composition decreases, it is assumed that the higher Curie temperature is produced. Otherwise, The increase in Ni (x) composition causes the magnetic susceptibility spectrum to shift to the left, with the Curie temperature's predicted value getting minor than the other. The nanocube-shaped material has a higher susceptibility value than the nanosphere-shaped material in terms of each Ni (x) composition variation at its maximum magnetic susceptibility.

Prevalence and Spectrum of Cancer Susceptibility Among Patients With Advanced Colorectal Polyps

Prevalence and Spectrum of Cancer Susceptibility Among Patients With Advanced Colorectal Polyps

Stimulated spin noise in an activated crystal

In spin noise spectroscopy, the magnetic susceptibility spectrum is known to be provided by the spin-system untouched by any external perturbation, or, better to say, disturbed only by its thermal bath. We propose a new version of spin noise spectroscopy, with the detected magnetization (Faraday-rotation) noise being “stimulated” by an external fluctuating magnetic field with a quasiwhite spectrum. An experimental study of the stimulated spin noise performed on a BaF2:U3+ crystal in a longitudinal magnetic field has revealed specific features of this approach and allowed us to identify the Van-Vleck and population-related contributions to the AC susceptibility of the system and to discover unusual magnetic-field dependence of the longitudinal spin relaxation rate in low magnetic fields. It is shown that spectra of the stimulated and spontaneous spin noise, being both closely related to the spin-system magnetic susceptibility, are still essentially different. Distinctions between the two types of the spin-noise spectra and two approaches to spin noise spectroscopy are discussed.

The Phase Diagram and Exotic Magnetostrictive Behaviors in Spinel Oxide Co(Fe1-xAlx)2O4 System.

We report the magnetic and magnetostrictive behaviors of the pseudobinary ferrimagnetic spinel oxide system (1−x)CoFe2O4–xCoAl2O4 [Co(Fe1−xAlx)2O4], with one end-member being the ferrimagnetic CoFe2O4 and the other end-member being CoAl2O4 that is paramagnetic above 9.8 K. The temperature spectra of magnetization and magnetic susceptibility were employed to detect the magnetic transition temperatures and to determine the phase diagram of this system. Composition dependent and temperature dependent magnetostrictive behaviors reveal an exotic phase boundary that separates two ferrimagnetic states: At room temperature and under small magnetic fields (∼500 Oe), Fe-rich compositions exhibit negative magnetostriction while the Al-rich compositions exhibit positive magnetostriction though the values are small (<10 ppm). Moreover, the compositions around this phase boundary at room temperature (x = 0.35, 0.4, 0.45, 0.5) exhibit near-zero magnetostriction and enhanced magnetic susceptibility, which may be promising in the applications for magnetic cores, current sensors, or magnetic shielding materials.

Ferromagnetic and magnetostrictive properties of Tb0.3Dy0.7(Co1−xFex)2 alloys

Morphotropic phase boundary (MPB) have aroused wide interests due to the exotic properties exhibited by the compositions around MPB [Tb1−xDyxCo2, PRL 104, 197201 (2010); Tb1−xDyxFe2, PRL 111, 017203 (2013)]. By combining the two MPB compositions Tb0.3Dy0.7Co2 and Tb0.3Dy0.7Fe2, we designed a pseudo-binary system Tb0.3Dy0.7(Co1−xFex)2. The phase diagram is determined from the temperature spectra of magnetic susceptibility and magnetization. A Griffiths-like phase appears above the Curie temperature and gradually vanishes as the Fe content increases to x = 0.8. Magnetic hysteresis and magnetoelastic behavior are also investigated. Compared with the Terfenol-D composition x = 1.0, x = 0.8 exhibits higher Curie temperature (707 K) and comparable magnetostriction (818 ppm), which may be used in the sensors or transducers at high temperature.

Synthesis, Characterization and Biological Evaluation of Fe(III) and Cu(II) Complexes with 2,4-Dinitrophenyl hydrazine and Thiocyanate Ions

The metal complexes of Fe(III) and Cu(II) were prepared by using 2,4-dinitrophenyl hydrazine (DNPH) and thiocyanate (SCN) with stirrer refluxed for about 6 h. The prepared Fe(III) and Cu(II) complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility and electronic spectrum, FT-IR spectral studies. The result suggested the octahedral geometry for Fe(III) and Cu(II) complexes. Powder X-ray diffraction indicate the crystalline nature of the metal complexes. The antimicrobial activities of the Fe(III) and Cu(II) complexes were tested with various micro organisms by disc diffusion method. The antimicrobial results indicate that the metal complexes are highly active with compared to the free ligand. The in vitro antioxidant activity of the free ligand and its metal complexes was assayed by radical scavenging activity (DPPH). The result proposed that Fe (III) and Cu(II) complexes exhibited strong antioxidant activity than that of the ligand.

Linear complex susceptibility of long-range interacting dipoles with thermal agitation and weak external ac fields

An analytical formula for the linear complex susceptibility of dipolar assemblies subjected to thermal agitation, long-range interactions, and an externally applied uniform sinusoidal field of weak amplitude is derived using the forced rotational diffusion equation of Cugliandolo et al. [Phys. Rev. E 91, 032139 (2015)] in the virial approximation. If the Kirkwood correlation factor of the dipolar assembly ${g}_{K}$ exceeds unity, a thermally activated process arising from the interaction-specific component arises, while for ${g}_{K}&lt;1$ the susceptibility spectrum normalized by its static value is practically unaltered with respect to that of the ideal gas phase.

In vitro activity of four triazole antifungal drugs against clinically common and uncommon yeast species.

Background and Purpose:Incidence of fungal infections caused by opportunistic fungal pathogens, such as yeasts and yeast-like species, has undergone an increase in otherwise healthy individuals. These pathogens account for high mortality and show reduced susceptibility to the routine antifungal drugs. Accordingly, antifungal susceptibility testing is an urgent need in the determination of the susceptibility spectrum of antifungals and selection of appropriate antifungal agents for the management of patients with fungal infection.Materials and Methods:The present study was conducted on 110 yeast strains belonging to 15 species recovered from clinical specimens. Susceptibility of the isolates to four antifungal drugs (i.e., fluconazole, itraconazole, voriconazole, and posaconazole) was tested according to the Clinical and Laboratory Standards Institute guidelines M27-A3 and M27-S4.Results:Fluconazole exhibited no activity against 4.3% (n=2) of C. albicans isolates, whereas the remaining 44 isolates had a minimum inhibitory concentration (MIC) range of 0.125-4 μg/ml. Voriconazole had the lowest geometric mean MIC (0.03 µg/ml) against all isolated yeast species, followed by posaconazole (0.07 µg/ml), itraconazole (0.10 µg/ml), and fluconazole (0.60 µg/ml). Overall, all of the isolates had reduced voriconazole MICs with a MIC range of 0.016-0.5 μg/ml, except for one isolate of C. albicans that had a MIC of 1 μg/ml. Candida haemulonii as a multidrug-resistant fungus showed a fluconazole MIC of > 64 μg/ml.Conclusion:The current study provides insight into the antifungal susceptibility profiles of clinically common and uncommon yeast species to four triazole antifungal agents. According to our findings, voriconazole was the most active agent. Awareness about antifungal susceptibility patterns is highly helpful in the selection of appropriate antifungal drugs and identification of the efficiency of the currently used agents.

Spectrum of susceptibility to air quality and weather in individual children with atopic dermatitis.

Exposure to air pollution aggravates symptoms of atopic dermatitis (AD) in children in the population studies. Variability in individual patient's response from individual susceptibility is needed to be explored. This study aimed to investigate spectrum of individual variability in the associations between AD symptoms and air quality. We enrolled 89 children aged 0-6years with AD (22890 person-days). Daily manifestation of symptoms was recorded for an average of 257days (range 100-499). Both an individual analysis using logistic regression models and an overall analysis using a generalized estimating equation were performed. The odds ratios of an individual ranged 0.24-8.11 for particulate matter <10μm in diameter (PM10 ), 0.09-101.92 for nitrogen oxide (NO2 ), 0.03-44.00 for ozone (O3 ), 0.11-58.30 for sulfur dioxide (SO2 ), 0.00-15.83 for carbon monoxide (CO), 0.00-39446.94 for temperature, and 0.03-5.18 for relative humidity, demonstrating a wide individual variability. In the overall analysis, PM10 , NO2 , SO2 , and CO had a significantly positive association, whereas temperature and relative humidity were negatively associated with AD symptoms. Air pollution was responsible for aggravation of symptoms from 24.7% (O3 ) to 39.3% (SO2 ) of AD children. Overall, 71.9% of the AD children responded to at least one or more air pollution and weather variable. Responses of AD children to air pollution and weather variable were considerably variable among individuals. An individualized model would be useful to forecast and manage AD symptoms in patients.

Analysis on clinical distribution and drug resistance of Klebsiella pneumoniae isolated for 5 consecutive years

Objective: To analyze the clinical distribution and drug resistance of Klebsiella pneumoniae isolated from patients in a certain hospital and provide a basis for the rational use of antibiotics in the clinical treatment for the infection of Klebsiella pneumoniae . Methods: 1,192 strains of Klebsiella pneumoniae isolated from clinical specimens from 2012 to 2016 were collected. The strains were identified by VITEK-2 Compact Microbiological Identification System, and the corresponding results of the antimicrobial susceptibility test were interpreted in accordance with the standards recommended by Clinical and Laboratory Standards Institute (CLSI). Results: 1,192 strains of Klebsiella pneumoniae were mainly isolated from sputum (65.6%), and most of them were from Respiratory Medicine Department and Medical Intensive Care Unit of Respiratory Medicine Department (MICU), accounting for 41.4%. Out of 1,192 strains, 448 strains were detected to produce extended-spectrum beta-lactamases (ESBLs), accounting for 37.6%. In addition, the detection rates of ESBL-producing Klebsiella pneumoniae for 5 consecutive years showed an increasing trend year by year, and they were higher than the national average values published by China Antimicrobial Resistance Surveillance System (CARSS) in the corresponding period. The drug resistance rate of ESBL-producing Klebsiella pneumoniae was significantly higher than that of non ESBL-producing strains. Conclusions: The infection caused by Klebsiella pneumoniae mainly occurs in the lower respiratory tract, and the drug resistance rates of Klebsiella pneumoniae to antibiotics in the drug susceptibility spectrum are maintained at a high level. Therefore, the rational selection of antibiotics for the clinical treatment of lower respiratory tract infection caused by Klebsiella pneumoniae must be based on the production of ESBLs and the results of antimicrobial susceptibility test.

Analysis on clinical distribution and drug resistance of Klebsiella pneumoniae isolated for 5 consecutive years

Objective: To analyze the clinical distribution and drug resistance of Klebsiella pneumoniae isolated from patients in a certain hospital and provide a basis for the rational use of antibiotics in the clinical treatment for the infection of Klebsiella pneumoniae . Methods: 1,192 strains of Klebsiella pneumoniae isolated from clinical specimens from 2012 to 2016 were collected. The strains were identified by VITEK-2 Compact Microbiological Identification System, and the corresponding results of the antimicrobial susceptibility test were interpreted in accordance with the standards recommended by Clinical and Laboratory Standards Institute (CLSI). Results: 1,192 strains of Klebsiella pneumoniae were mainly isolated from sputum (65.6%), and most of them were from Respiratory Medicine Department and Medical Intensive Care Unit of Respiratory Medicine Department (MICU), accounting for 41.4%. Out of 1,192 strains, 448 strains were detected to produce extended-spectrum beta-lactamases (ESBLs), accounting for 37.6%. In addition, the detection rates of ESBL-producing Klebsiella pneumoniae for 5 consecutive years showed an increasing trend year by year, and they were higher than the national average values published by China Antimicrobial Resistance Surveillance System (CARSS) in the corresponding period. The drug resistance rate of ESBL-producing Klebsiella pneumoniae was significantly higher than that of non ESBL-producing strains. Conclusions: The infection caused by Klebsiella pneumoniae mainly occurs in the lower respiratory tract, and the drug resistance rates of Klebsiella pneumoniae to antibiotics in the drug susceptibility spectrum are maintained at a high level. Therefore, the rational selection of antibiotics for the clinical treatment of lower respiratory tract infection caused by Klebsiella pneumoniae must be based on the production of ESBLs and the results of antimicrobial susceptibility test.

1016. Bloodstream Infection Survey in High-Risk Oncology Patients (BISHOP) With Fever and Neutropenia (FN): Predictors for Morbidity and Mortality

BackgroundBlood stream infection (BSI) during neutropenia is associated with high risk for morbidity and mortality in patients with hematologic malignancies receiving chemotherapy or undergoing hematopoietic cell transplant (HCT). We sought to identify factors associated with increased risk for critical illness (CI) morbidities within 7 days of BSI with index FN following chemotherapy.MethodsA prospective ongoing survey among 14 high-volume US cancer centers submitting clinical and microbiologic data from consecutive HM patients with blood stream infection (BSI) during first FN after cytotoxic chemotherapy or HCT. We evaluated factors influencing poor outcomes defined as critical illness (need for pressor support, mechanical ventilation, new pneumonia or new BSI) within 7 days of BSI with index FN. Concordance between antibiotic and BSI isolate was determined by investigator (AZ, AF) interpretation of susceptibility reports provided by each center compared with the initial antimicrobial regimen (IAR) used, for single organism bacteremias only.ResultsAmong 294 FN bacteremic episodes (93 HCT) were 336 bacterial pathogens (48.5% Gram-negative [GN], 46.5% Gram-positive [GP], and 6% anaerobes). Death occurred in 11/294 (4%) and 41/294 (14%) had CI by day 8. At FN presentation, mean MASCC score of those with CI vs. those without was 16.9 vs. 18.6 (P = 0.03) and there was a trend toward higher mean PITT scores for patients with CI by day 8 vs. those without (1.54 vs. 0.82 (P = 0.08)). Among GN bacteremias, 15% developed CI vs. 14.5% in nonviridans group Streptococci (VGS) GP bacteremias, and 10.9% in VGS bacteremias (NS). Among patients with single organism bacteremias (88% of all BSI), mismatch of IAR coverage with isolate susceptibilities occurred in 16.7% (38/227). Among patients whom IAR was active vs. inactive against BSI isolate, 16% vs 14.3%, respectively, developed CI (P = 0.81).ConclusionThese data indicate that the MASCC score applied to high-risk inpatients may be a predictor for CI in the first week after bacteremia FN. The PITT shows less correlation with poor outcomes. There was no association between isolate type (GN, GP, or VGS) and CI. Notably there was no association between mismatched BSI susceptibility and antimicrobial spectrum of the IAR and early CI.Disclosures A. G. Freifeld, Merck: Investigator, Research grant. A. Zimmer, Merck: Investigator, Research grant. S. Pergam, Merck: Consultant, Consulting fee. Chimerix: Consultant, Consulting fee. K. V. Rolston, Merck: Investigator, Research grant. JMI Laboratories: Investigator, Research grant. Shionogi (Japan): Investigator, Research grant. S. Shoham, Merck: Investigator and Scientific Advisor, Consulting fee and Grant recipient. Astellas: Investigator, Grant recipient. Shionogi (Japan): Investigator, Grant recipient. Gilead: Investigator, Grant recipient. Shire: Investigator, Grant recipient. T. J. Walsh, Merck: Grant Investigator, Research grant. Atellas: Consultant, Grant Investigator and Scientific Advisor, Consulting fee and Research grant. Gilead: Scientific Advisor, Consulting fee. Allergan: Grant Investigator and Scientific Advisor, Consulting fee and Research grant. Scynexis: Grant Investigator, Research grant. Amplyx: Grant Investigator, Research grant. Shionogi: Scientific Advisor, Consulting fee. J. A. Young, GSK: Investigator, The University of Minnesota is reimbursed for contract costs associated with conducting clinical trials of vaccine. I receive no personal financial benefit. Y. Zhang, Merck: Investigator, Research grant. J. Meza, Merck: Investigator, Research grant.

Theory of the dynamic magnetic susceptibility of ferrofluids

The dynamic magnetic response of a ferrofluid to a weak ac magnetic field is studied using statistical mechanical theory and Brownian dynamics simulations, taking account of dipole-dipole interactions between the constituent ferromagnetic colloidal particles, and the presence of a range of particle sizes. The effects of interactions and polydispersity on the frequency dispersion are shown to be substantial: the amplitude of the response can be about twice that of a noninteracting system; the frequency for peak power loss can be reduced by about one half; and polydispersity effects can even change the qualitative appearance of the susceptibility spectrum.

Phenotypic antibiotic susceptibility testing of pathogenic bacteria using photonic readout methods: recent achievements and impact.

The development of antibiotic resistances in common pathogens is an increasing challenge for therapy of infections and especially severe complications like sepsis. To prevent administration of broad-spectrum and potentially non-effective antibiotics, the susceptibility spectrum of the pathogens underlying the infection has to be determined. Current phenotypic standard methods for antibiotic susceptibility testing (AST) require the isolation of pathogens from the patient and the subsequent culturing in the presence of antibiotics leading to results only after 24-72h. Since the early initialization of an effective antibiotic therapy is crucial for positive treatment result in severe infections, faster methods of AST are urgently needed. A large number of different assay systems are currently tested for their practicability for fast detection of antibiotic resistance profiles. They can be divided into genotypic ones which detect the presence of certain genes or gene products associated with resistances and phenotypic assays which determine the effect of antibiotics on the pathogens. In this mini-review, we summarize current developments in fast phenotypic tests that use photonic approaches and critically discuss their status. We further outline steps that are required to bring these assays into clinical practice.

The Belgian MicroArray Prenatal (BEMAPRE) database: A systematic nationwide repository of fetal genomic aberrations.

With the replacement of karyotyping by chromosomal microarray (CMA) in invasive prenatal diagnosis, new challenges have arisen. By building a national database, we standardize the classification and reporting of prenatally detected copy number variants (CNVs) across Belgian genetic centers. This database, which will link genetic and ultrasound findings with postnatal development, forms a unique resource to investigate the pathogenicity of variants of uncertain significance and to refine the phenotypic spectrum of pathogenic and susceptibility CNVs. The Belgian MicroArray Prenatal (BEMAPRE) consortium is a collaboration of all genetic centers in Belgium. We collected data from all invasive prenatal procedures performed between May 2013 and July 2016. In this three-year period, 13266 prenatal CMAs were performed. By national agreement, a limited number of susceptibility CNVs and no variants of uncertain significance were reported. Added values for using CMA versus conventional karyotyping were 1.8% in the general invasive population and 2.7% in cases with an ultrasound anomaly. Of the reported CNVs, 31.5% would have remained undetected with non-invasive prenatal test as the first-tier test. The establishment of a national database for prenatal CNV data allows for a uniform reporting policy and the investigation of the prenatal and postnatal genotype-phenotype correlation.

Coulomb effects on the photoexcited quantum dynamics of electrons in a plasmonic nanosphere

With recent experiments investigating the optical properties of progressively smaller plasmonic particles, quantum effects become increasingly more relevant, requiring a microscopic description. Using the density matrix formalism we analyze the photo-excited few-electron dynamics of a small nanosphere. Following the standard derivation of the bulk plasmon we particularly aim on elucidating the role of the Coulomb interaction. Calculating the dielectric susceptibility spectrum in the linear optical response we find discrete resonances resulting from a collective response mediated by the Coulomb interaction between the electrons. In the nonlinear regime, the occupations of the system exhibit oscillations between the interacting eigenstates. Our approach provides an ideal platform to study and explain nonlinear and quantum plasmonics, revealing that the photo-excited dynamics of plasmonic nano spheres has similarities with and combines characteristics of both, the well-known two-level Rabi dynamics, and the collective many-electron behavior typical of plasmons.