On the Hall effect in polycrystalline semiconductors

Some problems involved in the interpretation of Hall‐effect measurements in polycrystalline semiconductors have not been resolved, especially when the contribution of the boundaries is appreciable. Using the Herring theory of transport properties in inhomogeneous semiconductors, we present an alternative interpretation to that previously proposed. This model permits the calculation of the Hall coefficient under general conditions.

The love marriage : challenging Victorian myths in Anne Brontë’s 'The Tenant of Wildfell Hall'

La tesina analitza com Anne Brontë desafia el mite del casament romàntic a la novel·la The Tenant of Wildfell Hall. Argumento que aquesta crítica es fa mostrant les conseqüències nefastes d’un matrimoni (entre l’Arthur i l’Helen) basat en l’atracció i en la idea que una dona pot salvar un home de mala vida. Malgrat que la novel·la acaba amb un altre casament (entre l’Helen i en Gilbert), si s’analitza en detall es pot veure que presenta elements subversius. Per exemple, la seva unió està basada en igualtat intel·lectual i compatibilitat de caràcters, enlloc d’igualtat econòmica i social

Geographisk, physico-economisk och historisk beskrifning öfwer Birckala socken uti Åbo höfdingedöme : af Daniel Hall, commissions landmätare i Finland.

Offprint from: Samling af rön och afhandlingar, rörande landtbruket, som till Kongl. Wetenskaps Academien bilfwit ingifne, tom. 4.

Ajuste do modelo de Schumacher e Hall e aplicação de redes neurais artificiais para estimar volume de árvores de eucalipto

Objetivou-se, neste trabalho, avaliar o ajuste do modelo volumétrico de Schumacher e Hall por diferentes algoritmos, bem como a aplicação de redes neurais artificiais para estimação do volume de madeira de eucalipto em função do diâmetro a 1,30 m do solo (DAP), da altura total (Ht) e do clone. Foram utilizadas 21 cubagens de povoamentos de clones de eucalipto com DAP variando de 4,5 a 28,3 cm e altura total de 6,6 a 33,8 m, num total de 862 árvores. O modelo volumétrico de Schumacher e Hall foi ajustado nas formas linear e não linear, com os seguintes algoritmos: Gauss-Newton, Quasi-Newton, Levenberg-Marquardt, Simplex, Hooke-Jeeves Pattern, Rosenbrock Pattern, Simplex, Hooke-Jeeves e Rosenbrock, utilizado simultaneamente com o método Quasi-Newton e com o princípio da Máxima Verossimilhança. Diferentes arquiteturas e modelos (Multilayer Perceptron MLP e Radial Basis Function RBF) de redes neurais artificiais foram testados, sendo selecionadas as redes que melhor representaram os dados. As estimativas dos volumes foram avaliadas por gráficos de volume estimado em função do volume observado e pelo teste estatístico L&O. Assim, conclui-se que o ajuste do modelo de Schumacher e Hall pode ser usado na sua forma linear, com boa representatividade e sem apresentar tendenciosidade; os algoritmos Gauss-Newton, Quasi-Newton e Levenberg-Marquardt mostraram-se eficientes para o ajuste do modelo volumétrico de Schumacher e Hall, e as redes neurais artificiais apresentaram boa adequação ao problema, sendo elas altamente recomendadas para realizar prognose da produção de florestas plantadas.

Quantum Hall effect in 2 dimensional GaInAs structure

Transport properties of GaAs / δ – Mn / GaAs / InxGa1-xAs / GaAs structure with Mn δ – layer, which is separated from InxGa1-xAs quantum well (QW) by 3 nm thick GaAs spacer was investigated. This structure with high mobility was characterized by X-ray difractometry and reflectometry. Transport and electrical properties of the structure were measured by using Pulsed Magnetic Field System (PMFS). During investigation of the Shubnikov – de Haas and the Hall effects the main parameters of QW structure such as cyclotron mass, Fermi level, g – factor, Dingle temperature and concentration of holes were estimated. Obtained results show high quality of the prepared structure. However, anomalous Hall effect at temperatures 2.09 K, 3 K, 4.2 K is not clearly observed. Attempts to identify magnetic moment were made. For this purpose the polarity of the filed was changed to the opposite at each shot. As a result hysteresis loop was not observed in the magnetic field dependences of the anomalous Hall resistivity.This can be attributed to the imperfection of the experimental setup.

Mr [James] O'Grady arrivant à Caxton Hall [membre du Parlement anglais et secrétaire de la National Federation of General Workers] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 56233

Grève des cheminots anglais, Mr Arthur Henderson [secrétaire du Labor party] quittant Caxton Hall : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 56234

[16/7/20, salle de l'Albert Hall de Londres] match [de boxe entre] Tommy Burns [et Joe] Beckett : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60155

[16/7/20, salle de l'Albert Hall de Londres] match [de boxe entre] Tommy Burns [et Joe] Beckett : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60156

[16/7/20, salle de l'Albert Hall de Londres] match [de boxe entre] Tommy Burns [et Joe] Beckett : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60159

[16/7/20, salle de l'Albert Hall de Londres] match [de boxe entre] Tommy Burns [et Joe] Beckett : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60157

[16/7/20, salle de l'Albert Hall de Londres] match [de boxe entre] Tommy Burns [et Joe] Beckett : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60158

[16/7/20, salle de l'Albert Hall de Londres] match [de boxe entre] Tommy Burns [et Joe] Beckett : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60160

[16/7/20, salle de l'Albert Hall de Londres] match [de boxe entre] Tommy Burns [et Joe] Beckett : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 60162