Black hole entropy from Quantum Geometry

Quantum Geometry (the modern Loop Quantum Gravity using graphs and spin-networks instead of the loops) provides microscopic degrees of freedom that account for the black-hole entropy. However, the procedure for state counting used in the literature contains an error and the number of the relevant horizon states is underestimated. In our paper a correct method of counting is presented. Our results lead to a revision of the literature of the subject. It turns out that the contribution of spins greater then 1/2 to the entropy is not negligible. Hence, the value of the Barbero-Immirzi parameter involved in the spectra of all the geometric and physical operators in this theory is different than previously derived. Also, the conjectured relation between Quantum Geometry and the black hole quasi-normal modes should be understood again.Comment: a new section ``The spin probability distribution'' adde

Written output of the deaf and hard of hearing primary school students learning English as a foreign language

Contemporarily learning foreign languages it is a must for anybody who wants to acquire high quality education and be competitive on the job market. It is also true for the students who are deaf and hard of hearing. Their language disability makes it much more difficult to become a proficient foreign language user. The aim of the paper is to present the preliminary effects of the process of teaching and learning English as a foreign language to the deaf and hard of hearing students. The research presented was conducted in several primary Special Schools for the Deaf and Hard of Hearing around Poland. The study concentrates mainly on the deaf and hard of hearing students’ writing skills in English. Students’ written works were linguistically analyzed by the author of this research and also presented to “competent judges” – adult native English speakers. The results show that deaf and hard of hearing student are able to construct meaningful texts in English. However, they are very simple in their form and content. This problem needs further analysis, also the comparative ones

Evaluating the efficiency of decision making units using panel Data Envelopment Analysis – empirical example for Polish commercial banks

The author makes an attempt to assess the relative efficiency of Polish commercial banks using non-paramteric Data Envelopment Analysis. In the empirical research, use has been made of panel data – 24 commercial banks in 4 years (2001–2004). The results of sequential DEA method (which examines 24 banks individually in each year) are compared to the results of integral DEA method (which examines 24 banks in four years at the same time – one bank appears in such analysis four times, i.e. there is 24 × 4 = 96 objects under examination). Owing to this approach it is easier to reveal which unit is truly efficient and which one is only accidentally recognized as efficient. The author comes to the conclusion that the integral DEA method is more reliable, because the results are more stable and fewer units are recognized (incorrectly) as efficient.Data Envelopment Analysis (DEA), relative efficiency, commercial bank

Data Envelopment Analysis – a method for measuring the relative technical efficiency

In the article, the author presents Data Envelopment Analysis, which is a method for measuring relative technical efficiency. The idea of DEA method is illustrated by a simple example, where objects characterized by one input and one output only are considered. Next, a the basic DEA model (CCR model) is described and conditions are given, based on which a unit under examination can be considered efficient. The author also presents a short review of some basic CCR model modifications, which, e.g., allow the existence of variable returns to scale (in CCR model, it is assumed that returns to scale are constant), and simultaneous input and output model orientation – basic CCR model is input-oriented or outputoriented. The modifications may also consist in introducing nondiscretionary variables into DEA efficiency analysis or additional constrainsts to the basic CCR model.Data Envelopment Analysis (DEA), technical efficiency, efficiency frontier

Gravity quantized

..."but we do not have quantum gravity." This phrase is often used when analysis of a physical problem enters the regime in which quantum gravity effects should be taken into account. In fact, there are several models of the gravitational field coupled to (scalar) fields for which the quantization procedure can be completed using loop quantum gravity techniques. The model we present in this paper consist of the gravitational field coupled to a scalar field. The result has similar structure to the loop quantum cosmology models, except for that it involves all the local degrees of freedom because no symmetry reduction has been performed at the classical level.Comment: 18 pages; 1. We have extended section IIIC showing that the family of quantum Dirac observables constructed in the paper is in fact complete. 2. We have modified and extended section IIID by clarifying the classical meaning of the observables. 3. We have modified and extended section IIIE explaining the nature of the dynamic

Morphology of Root Canal Cross-sections of Resected Roots of First and Second Lower Molars

Precise preparation of the root canal ostium with a view to hermetical closing with retrograde root filling is an important prognostic factor determining the success of the procedure of tooth resection. Root canals interconnected with a narrow isthmus may cause problems both in endodontic treatment and in retrograde filling. The aim of this work is the research of the transverse cross-section of root canals of first and second lower molars on the resection model. The research encompasses 100 randomly selected molar teeth: 50 first and 50 second lower molars. The tooth root apexes were cut 3 mm below the apex and examined under an electron microscope, special attention being paid to the shape of root canal cross-sections. In the group of first molar teeth, in 20% the presence of an isthmus between canals in the proximal roots was observed; in the group of second molar teeth an isthmus between the canals of proximal roots occurred in 18% of the cases. It seems that the relatively high percentage (20%-18%) of the occurrence of an isthmus, 3 mm below the root apex, between two elongated transverse cross-section proximal root canals of first and second molars should encourage particular caution in the retrograde filling of the above-mentioned canals during the procedure of resection

A Method of Locating the Abutment Screw Access Channel with Cone-Beam Computed Tomography and a 3D-Printed Drilling Guide

In managing loose abutment screws, locating precisely the position of the screw access channel is difficult. This technique describes the use of cone-beam computed tomography (CBCT) and surgical guide planning software to locate the screw access channel with the intention of retrieving a loosened cement-retained implant-supported prosthesis. The method minimizes damage to the abutment crown assembly