Laboratory and intra-oral tests of the degradation of elastic chains

Two brands of elastic chain, Alastic (Unitek Co.) and Power Chain II (Ormco Co.), were tested for force development in laboratory and intra-oral experiments. During the laboratory test, the chains were extended to 180 and 215 per cent of their original passive length and the force exerted at this length was measured at the start and after 15 minutes, 2, 8 and 24 hours, 3 days and 1, 2, 3 and 4 weeks of continuous extension. The two brands behaved similarly. After 4 weeks, they had lost 25-30 per cent of their initial force. The decrease of the force value was greatest in the beginning of the test period, with a decline of 6-11 per cent during the first 15 minutes and 10-16 per cent during the first 2 hours. The intra-oral tests were performed in 10-25 subjects, who wore the elastic chains continuously for up to 4 weeks. The chains were extended up to 200 per cent of their original passive length. In one test, the force development was measured at the start and after 8 and 24 hours, 5 days and 1, 2, 3 and 4 weeks. In two other tests the force was measured after 1 day and 4 weeks, respectively. The two brands behaved similarly. The decline of the force value during intra-oral use was greater than in the laboratory tests. After 4 weeks, the force was only 43-52 per cent of the original value. The decline was greatest in the initial phase after insertion; after 8 hours the force had declined by 28-34 per cent. Thus, an initial force of 300g was reduced to 200g after 8 hours and to less than 150g after 4 weeks: in no specimen was the force after 4 weeks less than 100

Perception of pain as a result of orthodontic treatment with fixed appliances

The aims of this study were to investigate the intensity, location and duration of patients' discomfort following insertion of orthodontic appliances, and to examine for interactions between patient age, gender, appliance type and the perception of pain. After insertion of orthodontic appliances, 170 patients received eight questionnaires, one they completed and returned after 4 h, then one daily for 7 days. The respondents' ages ranged from 8-53 years (median age 13 years 7 months); 45 per cent were male and 55 per cent female. Of the patients, 65 per cent reported pain after 4 h and 95 per cent after 24 h. After 7 days, 25 per cent of the patients still reported discomfort. Patients' pain intensity scores were significantly higher for the anterior than for the posterior teeth. On day 1, 16 per cent took analgesics and 18 per cent reported being awakened the first night. Comparing a 2 × 4 appliance, a full appliance in one arch and in both arches, no statistical differences were found for reported pain frequency, general intensity of pain, pain at the teeth, discomfort when biting and chewing and analgesic consumption. The perception of general pain intensity, analgesic consumption, pain when eating and the influence of discomfort on daily life were all significantly greater in girls than in boys. Patients younger than 13 years reported pain significantly less frequently than the older patients. The highest frequency of pain was found in the group of 13-16 year olds. The pain intensity did not differ among the age group

Polarizations and Nullcone of Representations of Reductive Groups

The paper starts with the following simple observation. Let V be a representation of a reductive group G, and let f_1,f_2,...,f_n be homogeneous invariant functions. Then the polarizations of f_1,f_2,...,f_n define the nullcone of k 0} h(t) x = 0 for all x in L. This is then applied to many examples. A surprising result is about the group SL(2,C) where almost all representations V have the property that all linear subspaces of the nullcone are annihilated. Again, this has interesting applications to the invariants on several copies. Another result concerns the n-qubits which appear in quantum computing. This is the representation of a product of n copies of $SL_2$ on the n-fold tensor product C^2 otimes C^2 otimes ... otimes C^2. Here we show just the opposite, namely that the polarizations never define the nullcone of several copies if n <= 3. (An earlier version of this paper, distributed in 2002, was split into two parts; the first part with the title ``On the nullcone of representations of reductive groups'' is published in Pacific J. Math. {bf 224} (2006), 119--140.

The United States, PMSCs and the state monopoly on violence: Leading the way towards norm change

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2013 Sage.The proliferation of private military and security companies (PMSCs) in Iraq and Afghanistan has raised many questions regarding the use of armed force by private contractors. This article addresses the question of whether the increased acceptance of PMSCs indicates a transformation of the international norm regarding the state monopoly on the legitimate use of armed force. Drawing on theoretical approaches to the analysis of norm change, the article employs four measures to investigate possible changes in the strength and meaning of this norm: modifications in state behaviour, state responses to norm violation, the promulgation of varying interpretations of the norm in national and international laws and regulations, and changes in norm discourse. Based on an analysis of empirical evidence from the United States of America and its allies, the article concludes that these measures suggest that the USA is leading the way towards a transformation of the international norm of the state monopoly on violence, involving a revised meaning. Although this understanding has not yet been formally implemented in international law, it has allowed a growing number of countries to tolerate, accept or legalize the use of armed force by PMSCs in the international arena.The Alexander von Humboldt Foundation and the Peace Research Institute Frankfurt

Bose-Einstein Correlations of Three Charged Pions in Hadronic Z^0 Decays

Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 x 10^6 hadronic Z^0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near threshold was observed having an emitter source radius of r_3 = 0.580 +/- 0.004 (stat.) +/- 0.029 (syst.) fm and a strength of \lambda_3 = 0.504 +/- 0.010 (stat.) +/- 0.041 (syst.). The Coulomb correction was found to increase the \lambda_3 value by \~9% and to reduce r_3 by ~6%. The measured \lambda_3 corresponds to a value of 0.707 +/- 0.014 (stat.) +/- 0.078 (syst.) when one takes into account the three-pion sample purity. A relation between the two-pion and the three-pion source parameters is discussed.Comment: 19 pages, LaTeX, 5 eps figures included, accepted by Eur. Phys. J.

First Measurement of Z/gamma* Production in Compton Scattering of Quasi-real Photons

We report the first observation of Z/gamma* production in Compton scattering of quasi-real photons. This is a subprocess of the reaction e+e- to e+e-Z/gamma*, where one of the final state electrons is undetected. Approximately 55 pb-1 of data collected in the year 1997 at an e+e- centre-of-mass energy of 183 GeV with the OPAL detector at LEP have been analysed. The Z/gamma* from Compton scattering has been detected in the hadronic decay channel. Within well defined kinematic bounds, we measure the product of cross-section and Z/gamma* branching ratio to hadrons to be (0.9+-0.3+-0.1) pb for events with a hadronic mass larger than 60 GeV, dominated by (e)eZ production. In the hadronic mass region between 5 GeV and 60 GeV, dominated by (e)egamma* production, this product is found to be (4.1+-1.6+-0.6) pb. Our results agree with the predictions of two Monte Carlo event generators, grc4f and PYTHIA.Comment: 18 pages, LaTeX, 5 eps figures included, submitted to Physics Letters

The venom composition of the parasitic wasp Chelonus inanitus resolved by combined expressed sequence tags analysis and proteomic approach

<p>Abstract</p> <p>Background</p> <p>Parasitic wasps constitute one of the largest group of venomous animals. Although some physiological effects of their venoms are well documented, relatively little is known at the molecular level on the protein composition of these secretions. To identify the majority of the venom proteins of the endoparasitoid wasp <it>Chelonus inanitus </it>(Hymenoptera: Braconidae), we have randomly sequenced 2111 expressed sequence tags (ESTs) from a cDNA library of venom gland. In parallel, proteins from pure venom were separated by gel electrophoresis and individually submitted to a nano-LC-MS/MS analysis allowing comparison of peptides and ESTs sequences.</p> <p>Results</p> <p>About 60% of sequenced ESTs encoded proteins whose presence in venom was attested by mass spectrometry. Most of the remaining ESTs corresponded to gene products likely involved in the transcriptional and translational machinery of venom gland cells. In addition, a small number of transcripts were found to encode proteins that share sequence similarity with well-known venom constituents of social hymenopteran species, such as hyaluronidase-like proteins and an Allergen-5 protein.</p> <p>An overall number of 29 venom proteins could be identified through the combination of ESTs sequencing and proteomic analyses. The most highly redundant set of ESTs encoded a protein that shared sequence similarity with a venom protein of unknown function potentially specific of the <it>Chelonus </it>lineage. Venom components specific to <it>C. inanitus </it>included a C-type lectin domain containing protein, a chemosensory protein-like protein, a protein related to yellow-e3 and ten new proteins which shared no significant sequence similarity with known sequences. In addition, several venom proteins potentially able to interact with chitin were also identified including a chitinase, an imaginal disc growth factor-like protein and two putative mucin-like peritrophins.</p> <p>Conclusions</p> <p>The use of the combined approaches has allowed to discriminate between cellular and truly venom proteins. The venom of <it>C. inanitus </it>appears as a mixture of conserved venom components and of potentially lineage-specific proteins. These new molecular data enrich our knowledge on parasitoid venoms and more generally, might contribute to a better understanding of the evolution and functional diversity of venom proteins within Hymenoptera.</p