91 research outputs found
The Stern-Gerlach Experiment Revisited
The Stern-Gerlach-Experiment (SGE) of 1922 is a seminal benchmark experiment
of quantum physics providing evidence for several fundamental properties of
quantum systems. Based on today's knowledge we illustrate the different
benchmark results of the SGE for the development of modern quantum physics and
chemistry.
The SGE provided the first direct experimental evidence for angular momentum
quantization in the quantum world and thus also for the existence of
directional quantization of all angular momenta in the process of measurement.
It measured for the first time a ground state property of an atom, it produced
for the first time a `spin-polarized' atomic beam, it almost revealed the
electron spin. The SGE was the first fully successful molecular beam experiment
with high momentum-resolution by beam measurements in vacuum. This technique
provided a new kinematic microscope with which inner atomic or nuclear
properties could be investigated.
The original SGE is described together with early attempts by Einstein,
Ehrenfest, Heisenberg, and others to understand directional quantization in the
SGE. Heisenberg's and Einstein's proposals of an improved multi-stage SGE are
presented. The first realization of these proposals by Stern, Phipps, Frisch
and Segr\`e is described. The set-up suggested by Einstein can be considered an
anticipation of a Rabi-apparatus. Recent theoretical work is mentioned in which
the directional quantization process and possible interference effects of the
two different spin states are investigated.
In full agreement with the results of the new quantum theory directional
quantization appears as a general and universal feature of quantum
measurements. One experimental example for such directional quantization in
scattering processes is shown. Last not least, the early history of the
`almost' discovery of the electron spin in the SGE is revisited.Comment: 50pp, 17 fig
Fenites associated with carbonatite complexes : a review
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Carbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE- and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 689909
Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020
We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe
Transverse momentum spectra of charged particles in proton-proton collisions at GeV with ALICE at the LHC
The inclusive charged particle transverse momentum distribution is measured
in proton-proton collisions at GeV at the LHC using the ALICE
detector. The measurement is performed in the central pseudorapidity region
over the transverse momentum range GeV/.
The correlation between transverse momentum and particle multiplicity is also
studied. Results are presented for inelastic (INEL) and non-single-diffractive
(NSD) events. The average transverse momentum for is (stat.) (syst.) GeV/ and
\left_{\rm NSD}=0.489\pm0.001 (stat.) (syst.)
GeV/, respectively. The data exhibit a slightly larger than measurements in wider pseudorapidity intervals. The results are
compared to simulations with the Monte Carlo event generators PYTHIA and
PHOJET.Comment: 20 pages, 8 figures, 2 tables, published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/390
A population-scale temporal case–control evaluation of COVID-19 disease phenotype and related outcome rates in patients with cancer in England (UKCCP)
Patients with cancer are at increased risk of hospitalisation and mortality following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, the SARS-CoV-2 phenotype evolution in patients with cancer since 2020 has not previously been described. We therefore evaluated SARS-CoV-2 on a UK populationscale from 01/11/2020-31/08/2022, assessing case-outcome rates of hospital assessment(s), intensive care admission and mortality. We observed that the SARS-CoV-2 disease phenotype has become less severe in patients with cancer and the non-cancer population. Case-hospitalisation rates for patients with cancer dropped from 30.58% in early 2021 to 7.45% in 2022 while case-mortality rates decreased from 20.53% to 3.25%. However, the risk of hospitalisation and mortality remains 2.10x and 2.54x higher in patients with cancer, respectively. Overall, the SARS-CoV-2 disease phenotype is less severe in 2022 compared to 2020 but patients with cancer remain at higher risk than the non-cancer population. Patients with cancer must therefore be empowered to live more normal lives, to see loved ones and families, while also being safeguarded with expanded measures to reduce the risk of transmission
A conjectural extension of hecke's converse theorem
We formulate a precise conjecture that, if true, extends the converse theorem of Hecke without requiring hypotheses on twists by Dirichlet characters or an Euler product. The main idea is to linearize the Euler product, replacing it by twists by Ramanujan sums. We provide evidence for the conjecture, including proofs of some special cases and under various additional hypotheses
Dentin Bond Strength Of A Fluoride-releasing Adhesive System Submitted To Ph-cycling
To evaluate the microtensile bond strength (μTBS) of a fluoride-containing adhesive system submitted to a pH-cycling and storage time regimen for primary outcomes. As secondary outcomes the fluoride released amount was evaluated. Twelve dentin surfaces from sound third molar were divided into 2 groups according to adhesive systems: Clearfil SE Protect (PB) and Clearfil SE Bond (SE). Sticks obtained (1.0 mm2) from teeth were randomly divided into 3 subgroups according to storage regimen model: immediate (24h); 5-month deionized water (W); and pH-cycling model (C). All sticks were tested for μTBS in a universal testing machine. Fluoride concentration was obtained from 1-4 days and 30-day in W and 1-4 days in demineralization (DE)/remineralization (RE) solutions from C, using a fluoride-specific electrode. μTBS and fluoride released data were, respectively, submitted to ANOVA in a split plot design and Tukey, and Friedman’ tests (α=0.05). There was no significant interaction between adhesive system and storage regimen for μTBS. W showed the lowest μTBS values. There was no significant difference between 24 h and C models for μTBS. There was no significant difference between adhesive systems. Failure mode was predominantly cohesive within composite for the 24 h and W, for the C group it was mixed for SE and cohesive within composite for PB adhesive system. Fluoride concentrations in the DE/RE solutions were less than 0.03125 ppm and not detected in W. In conclusion, the fluoride-containing adhesive system performed similarly to the regular one. Hydrolytic degradation is the main problem with both adhesive systems, regardless of fluoride contents.256472478Hara, A.T., Queiroz, C.S., Freitas, P.M., Giannini, M., Serra, M.C., Cury, J.A., Fluoride release and secondary caries inhibition by adhesive systems on root dentine (2005) Eur J Oral Sci, 113, pp. 245-250Nakajima, M., Okuda, M., Ogata, M., Pereira, P.N.R., Tagami, J., Pashley, D.H., The durability of a fluoride-releasing resin adhesive system to dentin (2003) Oper Dent, 28, pp. 186-192Shinohara, M.S., Yamauti, M., Inoue, G., Nikaido, T., Tagami, J., Giannini M, et al. Evaluation of antibacterial and fluoride-releasing adhesive system on dentin--microtensile bond strength and acid-base challenge (2006) Dent Mater J, 25, pp. 545-552Nikaido, T., Ichikawa, C., Li, N., Takagaki, T., Sadr, A., Yoshida, Y., Effect of functional monomers in all-in-one adhesive systems of formation of enamel/dentin acid-base resistent zone (2011) Dent Mater J, 30, pp. 576-582Dos Santos, R.L., Pithon, M.M., Vaitsman, D.S., Araujo, M.T., De Souza, M.M., Nojima, M.G., Long-term fluoride release from resin-reinforced orthodontic cements following recharge with fluoride solution (2010) Braz Dent J, 21, pp. 98-103Passalini, P., Fidalgo, T.K., Caldeira, E.M., Gleiser, R., Nojima M Da, C., Maia, L.C., Preventive effect of fluoridated orthodontic resins subjected to high cariogenic challenges (2010) Braz Dent J, 21, pp. 211-215Basso, G.R., Della Bona, A., Gobbi, D.L., Cecchetti, D., Fluoride release from restorative materials (2011) Braz Dent J, 22, pp. 355-358Paschoal, M.A., Gurgel, C.V., Rios, D., Magalhaes, A.C., Buzalaf, M.A., Machado, M.A., Fluoride release profile of a nanofilled resin-modified glass ionomer cement (2011) Braz Dent J, 22, pp. 275-279Basso, G.R., Borba, M., Bona, A.D., Influence of different mechanisms of fluoride release from adhesive systems (2013) Braz Dent J, 24, pp. 522-526Da Silva, B.M., França, F.M., Flório, F.M., Basting, R.T., In situ anticariogenic effect of adhesive systems containing fluoride and MDPB (2010) Am J Dent, 23, pp. 75-80Armstrong, S.R., Vargas, M.A., Fang, Q., Laffoon, J.E., Microtensile bond strength of a total-etch 3-step, total-etch 2-step, self-etch 2-step, and a self-etch 1-step dentin bonding system through 15-month water storage (2003) J Adhes Dent, 5, pp. 47-56De Munck, J., Van Meerbeek, B., Yoshida, Y., Inoue, S., Vargas, M., Suzuki K, et al. Four-year water degradation of total-etch adhesives bonded to dentin (2003) J Dent Res, 82, pp. 136-140Peris, A.R., Mitsui, F.H.O., Lobo, M.M., Bedran-Russo, A.K.B., Marchi, G.M., Adhesive systems and secondary caries formation: Assessment of dentin bond strength, caries lesions depth and fluoride release (2007) Dent Mater, 23, pp. 308-316Itota, T., Nakabo, S., Iwai, Y., Konishi, N., Nagamine, M., Torii, Y., Inhibition of artificial secondary caries by fluoride-releasing adhesives on root dentin (2002) J Oral Rehabil, 29, pp. 523-527Imazato, S., Kinomoto, Y., Tarumi, H., Ebisu, S., Tay, F.R., Antibacterial activity and bonding characteristics of an adhesive resin containing antibacterial monomer MDPB (2003) Dent Mater, 19, pp. 313-319Donmez, N., Belli, S., Pashley, D.H., Tay, F.R., Ultrastructural correlates of in vivo/in vitro bond degradation in self-etch adhesives (2005) J Dent Res, 84, pp. 355-359Lobo, M.M., Gonçalves, R.B., Pimenta, L.A.F., Bedran-Russo, A.K.B., Pereira, N.R., In vitro evaluation of caries inhibition promoted by self-etching adhesive systems containing antibacterial agents (2005) J Biomed Mater Res B Appl Biomater, 75, pp. 122-127Shinkai, R.S., Cury, A.A., Cury, J.A., In vitro evaluation of secondary caries development in enamel and root dentin around luted metallic restoration (2001) Oper Dent, 26, pp. 52-59Carvalho, A.S., Cury, J.A., Fluoride release from some dental materials in different solutions (1999) Oper Dent, 24, pp. 14-19Toba, S., Pereira, P.N.R., Nikaido, T., Medical, T., Hill, C., Effect of topical application of fluoride gel on artificial secondary caries inhibition (2003) Int Chin J Dent, 3, pp. 53-61Burrow, M.F., Satoh, M., Tagami, J., Dentin bond durability after three years using a dentin bonding agent with and without priming (1996) Dent Mater, 12, pp. 302-307Reis, A.F., Carrilho, M.R.O., Ghaname, E., Pereira, P.N.R., Giannini, M., Nikaido T, et al. Effects of water-storage on the physical and ultramorphological features of adhesives and primer/adhesive mixtures (2010) Dent Mater J, 29, pp. 697-705Morel, E., Bellenger, V., Bocquet, M., Verdu, J., Structure-properties relationships for densely cross-linked epoxide-amine systems based on epoxide or amine mixtures (1989) J Mater Sci, 24, pp. 69-75Ferracane, J.L., Berge, H.X., Condon, J.R., In vitro aging of dental composites in water-effect of degree of conversion, filler volume, and filler/matrix coupling (1998) J Biomed Mater Res, 42, pp. 465-472White, D.J., The application of in vitro models to research on demineralization and remineralization of the teeth (1995) Adv Dent Res, 9, pp. 175-19
A case of neonatal sweet syndrome associated with mevalonate kinase deficiency
Abstract Background Sweet syndrome (SS), also known as acute febrile neutrophilic dermatosis, is an immunologic syndrome characterized by widespread neutrophilic infiltration. Histiocytoid Sweet syndrome (H-SS) is a histopathologic variant of SS. While SS most commonly occurs in adults, this case report discusses an infant patient who presented with H-SS. Case presentation Through a multidisciplinary approach, this patient was also found to have very early onset inflammatory bowel disease (VEO-IBD) and Mevalonate kinase-associated disease (MKAD). While prior case studies have characterized an association between VEO-IBD and MKAD, there is no literature describing the association of all three diagnoses this case: H-SS, VEO-IBD and MKAD. Initiation of canakinumab in this patient resulted in successful control of the disease. Conclusions This case highlights the importance of a multidisciplinary approach to rare diagnoses, and collaboration during cases with significant diagnostic uncertainty
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