In the past years the spotlight of the search for dark matter particles widened to the low mass region, both from theoretical and experimental side. We discuss results from data obtained in 2013 with ...a single detector TUM40. This detector is equipped with a new upgraded holding scheme to efficiently veto backgrounds induced by surface alpha decays. This veto, the low threshold of 0.6keV and an unprecedented background level for CaWO\(_4\) target crystals render TUM40 the detector with the best overall performance of CRESST-II phase 2 (July 2013 - August 2015). A low-threshold analysis allowed to investigate light dark matter particles (<3GeV/c\(^2\)), previously not accessible for other direct detection experiments.
Liposomes haptenated with tripeptide-enlarged dinitrophenyl (DNP) are known to act as thymus-independent antigens which induce a strong IgM response and only limited amounts of circulating IgG. When ...haptenated liposomes are used in vaccination studies, it is of practical importance to improve the immunogenicity of these complexes. Therefore, an evaluation was made of the potency of various substances to modulate the immune response in such a way that the total antibody production is increased, including a relative great increase of 2-mercaptoethanol (2-ME)-resistant antibodies and immunological memory is induced. The following substances were used: glycophorin A (GP-A), sialogangliosides (monosialo-, disialo- and trisialoganglioside), 6-0-stearoyl-MDP (MDP-SA) and lipid A (lip A). Lip A incorporated into liposomes was the only substance inducing considerable increases of both total and 2-ME-resistant haemagglutination (HA) titre after immunization. Depending on the dose tested, the sialic-acid-containing protein GP-A had a small and varying influence on the serum antibody response. Sialogangliosides transiently decreased in a dose-dependent manner the total antibody titre in serum. In contrast to lip A, the lipophilic bacterial adjuvant MDP-SA did not influence HA titres significantly. The number of plaque-forming cells (PFC) in the spleen was enhanced considerably after both primary and secondary immunization with liposomes containing lip A. The other substances tested induced only minor differences of the number of PFC. To some extent, lip A induced immunological memory. In conclusion, it can be stated that of the agents tested, only lip A is a potent and consistent stimulator of the humoral immune response to liposomes haptenated with DNP groups.
The effect of combinations of adjuvants on the humoral immune response to sheep red blood cells (SRBC) as antigen was investigated. Adjuvants belonging to two categories differing in physicochemical ...properties were used: surfactants (N,N-dioctadecyl-N',N'-bis-(2-hydroyethyl)propanediamine (CP-20,961), dimethyldioctadecylammonium bromide (DDA), neutrally charged liposomes, polyol (L 101 and L 121) and polyanions dextran sulfate (DXS), liquoid and suramine. All adjuvants but suramine augmented humoral responses to 2 X 10(7) SRBC measured by the number of direct anti-SRBC plaque-forming cells (PFC) in the spleen. The response to 2 X 10(6) SRBC was enhanced considerably by L 121 and DXS but hardly or not at all by the other adjuvants. Combinations of two adjuvants were made at distinct ratios (1:3, 2:2, and 3:1) and injected intraperitoneally with 2 X 10(6) SRBC. Low responses (5 X 10(3) PFC per spleen) were induced by combinations of liquoid or suramine with DDA or DXS, and by combinations of CP-20,961, liposomes, L 101 or L 121 with DDA. Combinations of the surfactants DDA, CP-20,961, liposomes, L 101 or L 121 with DXS evoked responses which were significantly higher than the sum of responses supported by the single adjuvants. Ratios of 1:3 or 2:2 (surfactant: DXS) resulted in the most effective combinations. The data obtained suggest that only adjuvants derived from two different physicochemical groups are able to act synergistically.
Large, Petabyte-scale data stores need detailed design considerations about distributing and replicating particular parts of the data store in a cost-effective way. Technical issues need to be ...analysed and, based on these constraints, an optimisation problem can be formulated. In this paper we provide a novel cost model for building a world-wide distributed Petabyte data store which will be in place starting from 2005 at CERN and its collaborating, world-wide distributed institutes. We elaborate on a framework for assessing potential system costs and influences which are essential for the design of the data store.
The experiment CRESST-II aims at the detection of dark matter with scintillating CaWO\(_4\) crystals operated as cryogenic detectors. Recent results on spin-independent WIMP-nucleon scattering from ...the CRESST-II Phase 2 allowed to probe a new region of parameter space for WIMP masses below 3 GeV/c\(^2\). This sensitivity was achieved after background levels were reduced significantly. We present extensive background studies of a CaWO\(_4\) crystal, called TUM40, grown at the Technische Universit\"at M\"unchen. The average beta/gamma rate of 3.51/kg keV day (1-40 keV) and the total intrinsic alpha activity from natural decay chains of \(3.08\pm0.04\) mBq/kg are the lowest reported for CaWO\(_4\) detectors. Contributions from cosmogenic activation, surface-alpha decays, external radiation and intrinsic alpha/beta emitters are investigated in detail. A Monte-Carlo based background decomposition allows to identify the origin of the majority of beta/gamma events in the energy region relevant for dark matter search.
We have measured field and temperature dependent magnetization of YbInNi4 to elucidate the nature of the magnetic transition at 3 K. For small fields we find magnetic order as previously reported. In ...contrast to former reports, however, our high resolution magnetization measurements down to 500 mK indicate dominating antiferromagnetic exchange interactions. We discuss the presence of geometrical frustration.
A sensitive ELISA has been developed to study immune responses in mice against Streptococcus pneumoniae type 3 capsular polysaccharide (S3PS) and hexasaccharide (HS)-protein conjugates derived ...therefrom. An advantage of the described system is that the same microtiter plates can be used for both ELISA and ELISPOT tests with a standardized washing procedure and diluent composition. S3PS induced predominantly IgM antibodies and minute amounts of IgG as measured by ELISA in serum. This was accompanied by large numbers (greater than 14000) of IgM spot-forming cells in the spleen. A shift towards IgG production was achieved by addition of lipid A. HS-protein conjugates induced predominantly IgG antibodies after booster immunization(s). Furthermore these conjugates induced large numbers (greater than 40000) of IgG spot-forming cells (SFC) in the spleen. ELISA and ELISPOT assays on microtiter plates are both reliable and highly reproducible assays for the evaluation of immune responses to S. pneumoniae antigens.
Synergistic effects of two synthetic adjuvants, dimethyldioctadecylammonium bromide (DDA) and dextran sulfate (DXS) on the humoral response to sheep red blood cells (SRBC) were investigated. Mice ...received intraperitoneal (ip) injections of adjuvant and antigen simultaneously. The number of plaque-forming cells (PFC) in the spleen were determined 5 days later and circulating anti-SRBC antibodies were measured till 16 weeks after immunization. Although combinations of DDA and DXS were very effective in enhancing the PFC response to both moderate (2 X 10(7 and low (2 X 10(6 doses of SRBC, synergy between the adjuvants was only observed at the low dose of SRBC. Optimal augmentation of the primary response to the low antigen dose was evoked by the combination of the highest dose tested of either adjuvant (1 mumol DDA and 1 nmol DXS) resulting in a 560-fold increase of the number of PFC in the spleen as compared to controls. Even combinations of relatively small amounts of both adjuvants were very effective in augmenting the response to SRBC. Mice receiving half the amounts of both adjuvants with 2 X 10(6) SRBC displayed increased numbers of PFC in the spleen at Day 5 as well as increased titers of total anti-SRBC antibodies at Week 1 and Week 2 and 2-mercaptoethanol-resistant antibodies from Week 4 till Week 16 as compared to the calculated sum of responses in mice which received either DDA (0.05 mumol per mouse) or DXS (0.05 nmol per mouse). The mechanism behind the synergy between these adjuvants is discussed and the possibility of discerning adjuvants on their modes of action is suggested.
