Phys. Rev. Lett. 129, 251103 - Published 16 December 2022 We present the measurement of the energy dependence of the boron flux in
cosmic rays and its ratio to the carbon flux \textcolor{black}{in an ...energy
interval from 8.4 GeV$/n$ to 3.8 TeV$/n$} based on the data collected by the
CALorimetric Electron Telescope (CALET) during $\sim 6.4$ years of operation on
the International Space Station. An update of the energy spectrum of carbon is
also presented with an increase in statistics over our previous measurement.
The observed boron flux shows a spectral hardening at the same transition
energy $E_0 \sim 200$ GeV$/n$ of the C spectrum, though B and C fluxes have
different energy dependences. The spectral index of the B spectrum is found to
be $\gamma = -3.047\pm0.024$ in the interval $25 < E < 200$ GeV$/n$. The B
spectrum hardens by $\Delta \gamma_B=0.25\pm0.12$, while the best fit value for
the spectral variation of C is $\Delta \gamma_C=0.19\pm0.03$. The B/C flux
ratio is compatible with a hardening of $0.09\pm0.05$, though a single
power-law energy dependence cannot be ruled out given the current statistical
uncertainties. A break in the B/C ratio energy dependence would support the
recent AMS-02 observations that secondary cosmic rays exhibit a stronger
hardening than primary ones. We also perform a fit to the B/C ratio with a
leaky-box model of the cosmic-ray propagation in the Galaxy in order to probe a
possible residual value $\lambda_0$ of the mean escape path length $\lambda$ at
high energy. We find that our B/C data are compatible with a non-zero value of
$\lambda_0$, which can be interpreted as the column density of matter that
cosmic rays cross within the acceleration region.
We have reported previously that tyrosine hydroxylase in the crude extract from rat striatum exists in the inactive form showing almost no activity at the physiological pH and that the inactive form ...is produced by the action of the end products of the enzyme, such as dopamine. The incubation of the enzyme with the end products resulted in not only the inactivation but also a remarkable stabilization of the enzyme. Catechols possessing amino groups but no negatively charged groups on the side chains (catecholamine-type catechols) were effective at a concentration as low as 10(-7) M in both the inactivation and stabilization of the enzyme. In contrast, catechols not possessing positively or negatively charged side chains (3,4-dihydroxyphenylethyleneglycol-type catechols) were ineffective at a concentration of 10(-7) M but effective at a concentration of 10(-6) M for both the inactivation and stabilization. Catechols possessing negatively charged groups (3,4-dihydroxyphenylacetic acid-type catechols) were ineffective even at a concentration of 10(-6) M. Thus, the end products of tyrosine hydroxylase appear to serve to keep the enzyme inactive and stable. The reaction mechanism of the conversion of the enzyme from the active/labile form to the inactive/stable form by dopamine was also investigated.
When brain calmodulin-dependent protein kinase IV is incubated with calmodulin-dependent protein kinase IV kinase under the
phosphorylation conditions in the presence of Ca /calmodulin, rapid initial ...incorporation of 1 mol of phosphate into 1 mol of the enzyme by the action of the kinase kinase
occurs, resulting in marked activation of the enzyme, and the subsequent incorporation of more than 3 mol of phosphate by
autophosphorylation occurs, resulting in no significant change in the activity (Okuno, S., Kitani, T., and Fujisawa, H.(1994)
J. Biochem. ( Tokyo ) 116, 923-930; Okuno, S., Kitani, T., and Fujisawa, H.(1995) J. Biochem. ( Tokyo ) 117, 686-690). After the maximal phosphorylation, the continued incubation in the presence of excess EGTA resulted in additional
autophosphorylation of the enzyme, leading to a complete loss of the Ca /calmodulin-dependent activity, while causing no significant change in the Ca /calmodulin-independent activity. The amino acid sequence analysis revealed that the autophosphorylation after removal of
Ca occurred on Ser , Ser , Ser , and Ser . Analysis by site-directed mutagenesis clearly showed that the autophosphorylation site responsible for the inactivation
is Ser . Thus, calmodulin-dependent protein kinase IV activated by the kinase kinase may lose its Ca /calmodulin-dependent activity by autophosphorylation on Ser located within the putative calmodulin-binding domain in the absence of Ca .
The silicon vertex detector for the super B factory Tsuboyama, T.; Abe, R.; Abe, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2005, Letnik:
541, Številka:
1
Journal Article
Recenzirano
The present B factories, running at the luminosity of
∼
1
×
10
34
cm
-
2
s
-
1
, have established a large time-dependent CP asymmetry in B decays. Upgrade of the KEKB accelerator to a luminosity of
5
...×
10
35
cm
-
2
s
-
1
, designated Super KEKB, has been proposed to extend physics reach beyond the standard model. Since measurement of time evolution of B mesons is essential, the silicon vertex detector, SVD, should be redesigned to meet the data rates and radiation backgrounds expected in this Super KEKB environment. The detector configuration, sensor options and read out electronics are discussed.
Nonylphenolpolyethoxylate polymers with different molecular weights were characterized by matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) and post source decay (PSD) ...experiments. The MALDI mass spectra indicated that the polymers have a repeated unit of (CH2CH2O) in the structure and contain small amounts of octyl- and decyl-phenolpolyethoxylate contaminants. The average molecular weights of the polymers obtained from the mass spectra were consistent with those of GPC measurements. Li+among alkali metal ions was found to be the best cationizing agent in PSD experiments. The PSD spectra suggested that the alkylphenol moiety in the end group of nonylphenolpolyethoxylate polymers contains alkyl structure of C6H13- group.
Silicon vertex detector for the KEK Super B factory Tsuboyama, T.; Aihara, H.; Arakawa, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2007, Letnik:
572, Številka:
1
Journal Article
Recenzirano
In order to extend the physics reach of the present B factories, a letter of intent for a Super B factory, with a luminosity of
4
×
10
35
cm
-
2
s
-
1
, was submitted in 2004. The paper summarizes ...recent progress in the design and technological solutions for the silicon vertex detector to be operated at the expected high data rate and background condition of a Super B factory.
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