ABSTRACT
Total bacterial count (TBC) and somatic cell count (SCC) are important quality parameters in goat milk. Exceeding the bulk milk TBC (BMTBC) thresholds leads to price penalties for Dutch dairy goat farmers. Controlling these milk quality parameters can be challenging, especially around kidding. First, we describe the variation and the peaks around kidding of TBC and SCC in census data on Dutch bulk milk over the last 22 years. Second, to explore causes of these elevations, we studied the variation of TBC and SCC in individual goat milk from 3 weeks before to 5 weeks after kidding and their association with systemic response markers interferon-γ (IFN-γ), calprotectin, ß-hydroxybutyrate (BHB), body condition score (BCS) and fecal consistency. We visited 4 Dutch dairy goat farms weekly for 10 to 16 weeks around kidding. Some of the goats had been dried off, other goats were milked continuously throughout pregnancy. A total of 1,886 milk samples from 141 goats were collected for automated flowcytometric quantification of TBC and SCC measurement. IFN-γ, calprotectin and BHB were determined twice in blood of the same goats, most samples were collected after kidding. The BCS and fecal consistency were scored visually before and after kidding. We found a strong correlation between TBC and SCC (Spearman's rho = 0.87) around kidding. Furthermore, in the third week before kidding, the average TBC (5.67 log10 cfu/mL) and SCC (6.70 log10 cells/mL) were significantly higher compared with the fifth week after kidding, where the average TBC decreased to 4.20 log10 cfu/mL and the average SCC decreased to 5.92 log10 cells/mL. In multivariable linear regression models, farm and stage of lactation were significantly associated with TBC and SCC, but none of the systemic response markers correlated with TBC or SCC. In conclusion, TBC and SCC in dairy goats were high in late lactation and decreased shortly after parturition. For SCC, the dilution effect might have caused the decrease, but this was not plausible for TBC. Moreover, the excretion of bacteria and cells in goat milk was not associated with the selected systemic response markers that were chosen as a read out for general immunity status, intestinal health and metabolic diseases. Therefore, we assume that the TBC increase before kidding and the decrease after parturition is caused by other systemic, possibly hormonal, processes. To reduce BMTBC and BMSCC, it would be advisable to keep milk of goats with highest numbers of bacteria and cells in their milk out of the bulk milk during end lactation. Further studies are needed to investigate the effects of withholding this end lactation milk from the bulk tank.
ABSTRACT
We present a novel ultrastable superconducting radio-frequency (RF) ion trap realized as a combination of an RF cavity and a linear Paul trap. Its RF quadrupole mode at 34.52 MHz reaches a quality factor of Q ≈ 2.3 × 105 at a temperature of 4.1 K and is used to radially confine ions in an ultralow-noise pseudopotential. This concept is expected to strongly suppress motional heating rates and related frequency shifts that limit the ultimate accuracy achieved in advanced ion traps for frequency metrology. Running with its low-vibration cryogenic cooling system, electron-beam ion trap, and deceleration beamline supplying highly charged ions (HCIs), the superconducting trap offers ideal conditions for optical frequency metrology with ionic species. We report its proof-of-principle operation as a quadrupole-mass filter with HCIs and trapping of Doppler-cooled 9Be+ Coulomb crystals.
ABSTRACT
Precision spectroscopy of atomic systems1 is an invaluable tool for the study of fundamental interactions and symmetries2. Recently, highly charged ions have been proposed to enable sensitive tests of physics beyond the standard model2-5 and the realization of high-accuracy atomic clocks3,5, owing to their high sensitivity to fundamental physics and insensitivity to external perturbations, which result from the high binding energies of their outer electrons. However, the implementation of these ideas has been hindered by the low spectroscopic accuracies (of the order of parts per million) achieved so far6-8. Here we cool trapped, highly charged argon ions to the lowest temperature reported so far, and study them using coherent laser spectroscopy, achieving an increase in precision of eight orders of magnitude. We use quantum logic spectroscopy9,10 to probe the forbidden optical transition in 40Ar13+ at a wavelength of 441 nanometres and measure its excited-state lifetime and g-factor. Our work unlocks the potential of highly charged ions as ubiquitous atomic systems for use in quantum information processing, as frequency standards and in highly sensitive tests of fundamental physics, such as searches for dark-matter candidates11 or violations of fundamental symmetries2.
ABSTRACT
In vacuo cryogenic environments are ideal for applications requiring both low temperatures and extremely low particle densities. This enables reaching long storage and coherence times, for example, in ion traps, essential requirements for experiments with highly charged ions, quantum computation, and optical clocks. We have developed a novel cryostat continuously refrigerated with a pulse-tube cryocooler and providing the lowest vibration level reported for such a closed-cycle system with 1 W cooling power for a <5 K experiment. A decoupling system suppresses vibrations from the cryocooler by three orders of magnitude down to a level of 10 nm peak amplitudes in the horizontal plane. Heat loads of about 40 W (at 45 K) and 1 W (at 4 K) are transferred from an experimental chamber, mounted on an optical table, to the cryocooler through a vacuum-insulated massive 120 kg inertial copper pendulum. The 1.4 m long pendulum allows installation of the cryocooler in a separate, acoustically isolated machine room. At the experimental chamber, we measured the residual vibrations using an interferometric setup. The positioning of the 4 K elements is reproduced to better than a few micrometer after a full thermal cycle to room temperature. Extreme high vacuum on the 10-15 mbar level is achieved. In collaboration with the Max-Planck-Institut für Kernphysik, such a setup is now in operation at the Physikalisch-Technische Bundesanstalt for a next-generation optical clock experiment using highly charged ions.
ABSTRACT
The transfer film on steel spheres formed in reciprocating sliding against nanocomposite coatings based on nanocrystalline WC1-x in amorphous carbon matrix is characterized and correlated with the tribological properties measured by a precision microtribometer. With the presence of transfer film, a coefficient of friction approximately 0.13 and a depth wear rate approximately 0.35 x 10(-10) m/N.Pass were obtained. The central zone of the transfer film covering approximately 25% of the Hertz contact area is intact while cracks and wear debris are found in the vast peripheral area. It is also heavily oxidized due to the absence of carbon, which is located at the peripherals and acts as lubricants. We propose that the oxidation of WC and adhesion of the oxides to the surface of sphere is the main mechanism for the buildup of the transfer films. With the thickening of the film, the internal stress increases. Under the shear stress, spalling and cracking of the transfer film take place. The overall tribological performance of the coatings is therefore a competing process of buildup and spalling of transfer films.
ABSTRACT
In this work, we propose a method to estimate basic parameters like the rms roughness and the mean grain size of nanocrystalline thin films on rough substrates. The method is based on the analysis of the power spectral density (PSD) of the surface profile, which allows distinguishing between the two participating components from surface and film. The effectiveness will be demonstrated for thin NiO(x) layers for gas sensing on Al(2)O(3) ceramic substrates, and for protective WC coatings on steel.
ABSTRACT
Knowledge of tip geometry is necessary for reproducible atomic force microscope (AFM) measurements. This is particularly important for measurements in contact mode, in which a certain wear of the tip will always occur. For small or flat structures or for structures of larger dimensions, knowledge of the tip radius and the entire tip geometry is important. Additionally, the tilt of the tip in relation to the sample is of importance. Normally, very complicated lithographically manufactured structures for tip characterization are used. In contrast, the structures shown in this work are very simple. For measuring the tip geometry very thin foils patterned by focused ion beam (FIB) were used. In this work we demonstrate the possibility of determining the AFM tip geometry and the tilt based on several different large structures. A proven algorithm was developed for the reconstruction of the tips. The shape of FIB-structured foils was determined by electron microscopy prior to AFM measurements. This new method for determining tip shape is also presented as it compares to other current methods. In this case a discussion on the stability and advantages of the new method is presented.
ABSTRACT
Gametophore induction in moss by Agrobacterium tumefaciens was inhibited by addition of lipopolysaccharide (LPS) from A. tumefaciens. The LPS did not affect bacterial viability or appear to bind to bacterial cells. LPS from nonbinding Agrobacterium radiobacter was not effective in reducing gametophore formation. A. tumefaciens LPS, if added 24 hours after addition of viable bacterial cells, had no effect in reducing gametophore formation. The polysaccharide portion of the LPS was identified as the binding component necessary for attachment of agrobacteria for induction of gametophores in moss and tumors in higher plants.
ABSTRACT
Eight species of mosses studied were divided into two groups on the basis of their developmental responses to ribosyl-trans-zeatin and Agro-bacterium tumefaciens B(6). All eight produced either gametophores or callus on the protonema in response to 6-(gamma,gamma-dimethylallylamino) purine and trans-zeatin. Three which produced normal gametophores with A. tumefaciens yielded callus or abnormal gametophores with ribosyl-trans-zeatin. Ribosyl-trans-zeatin and A. tumefaciens were relatively ineffective on five other mosses. Characteristics of protonemal growth common to each of these two groups are described.
ABSTRACT
The focus path of a laser beam deflected by a prismatic polygon mirror was calculated. It is shown that the larger the focal distance of the objective or the polygon radius, the closer the focus path approaches a straight scanning line. Especially in the case of small pattern scanning, a remarkably small deviation between actual focus path and straight scanning line can be achieved by suitable sizing and arrangement of the optical elements.
ABSTRACT
The activities of isomers of zeatin, ribosyl-zeatin, and 6-(gamma,gamma-dimethylallylamino) purine (i(6)Ade) on the moss Funaria hygrometrica are compared by measuring the ability of the cytokinins to induce callus or gametophores. The cis- and trans-ribosyl-zeatins were inactive, and therefore this kind of bioassay cannot be used as evidence for the presence or absence of a cytokinin in tests on natural products.
