The author explores the notion of friendship by drawing on personal and ministry experience, as well as on philosophical and biblical insights, in order to suggest a dynamic practice of pastoral care ...and a process of ministry formation which transcends the professional paradigm and the peership principle. He suggests that the power to bless, the ability to extend grace, and the potential for change are dynamics of friendship which are effective both in pastoral care and in ministry formation.
The body of research on the teaching-learning process in mathematics education is top heavy, especially at the secondary level. The literature shows off a huge upper torso of research thickly muscled ...with teaching strategies, however this upper body of teaching knowledge rests precariously on a relatively skinny pair of legs which represent the community's views of how mathematics is learned. Somehow the research on what represents good mathematics teaching paradoxically outweighs the educational community's sense of what embodies complex learning. After a comprehensive examination of this literature, I concluded that the voices of students were noticeably absent from the research in mathematics education. Instead, most researchers in this field have assumed some theoretical orientation toward learning, like behaviorism, constructivism, or social constructivism, and have collected evidence of learning based on that orientation. In my opinion, this outsider's view has given the educational community a rather distorted sense of how mathematics is learned. Thus, in my study I have attempted to build a definition of learning from the perspective of those learners old enough to possess vast amounts of knowledge about how they learn. As a result, this qualitative study was designed in the phenomenological tradition. The core meanings that five hundred high school students, mostly of color, placed on the phenomenon of learning were reduced to a description of the fundamental structure of their best learning moments. Significantly, this structure was not equivalent to any of the three major learning theory orientations, yet was related to each. In the final analysis, it was concluded that students had perceived their best learning moments as a tension between two competing concerns, the first interpreted as their concern over precision and the second as their concern over purpose. The significance of this finding was analyzed by contrasting this structure with each of the three major learning theories. Further, the impact of this structure on other fields of educational research was also discussed, including its potential influence on teacher education, the reform movement in mathematics education, research on authentic assessment, and the study of epistemological beliefs.
Examines Friedrich Schleiermacher's approach to practical theology, and, after listening critically to this historical voice, draws some conclusions for a contemporary understanding of pastoral ...theology as a discipline.
The optical properties of atomically thin transition metal dichalcogenide (TMDC) semiconductors are shaped by the emergence of correlated many-body complexes due to strong Coulomb interaction. ...Exceptional electron–hole exchange predestines TMDCs to be used to study fundamental and applied properties of Coulomb complexes such as valley depolarization of excitons and fine-structure splitting of trions. Biexcitons in these materials are less well understood and it has been established only recently that they are spectrally located between excitons and trions. Here we show that biexcitons in monolayer TMDCs exhibit a distinct and rich fine structure on the order of millielectronvolts due to electron–hole exchange. Ultrafast pump–probe experiments on monolayer WSe2 reveal decisive biexciton signatures and a fine structure in excellent agreement with a microscopic theory. We provide a pathway to understand the complex spectral structure of higher-order Coulomb complexes in TMDCs going beyond the usual classification scheme in terms of four-particle configurations.
Multiresistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) cause serious postoperative infections. A skin tolerant far-UVC (< 240 nm) irradiation system for their ...inactivation is presented here. It uses UVC LEDs in combination with a spectral filter and provides a peak wavelength of 233 nm, with a full width at half maximum of 12 nm, and an irradiance of 44 µW/cm
. MRSA bacteria in different concentrations on blood agar plates were inactivated with irradiation doses in the range of 15-40 mJ/cm
. Porcine skin irradiated with a dose of 40 mJ/cm
at 233 nm showed only 3.7% CPD and 2.3% 6-4PP DNA damage. Corresponding irradiation at 254 nm caused 15-30 times higher damage. Thus, the skin damage caused by the disinfectant doses is so small that it can be expected to be compensated by the skin's natural repair mechanisms. LED-based far-UVC lamps could therefore soon be used in everyday clinical practice to eradicate multiresistant pathogens directly on humans.
Abstract
AlGaN-based far ultraviolet-C (UVC) light emitting diodes (LEDs) with a peak emission wavelength below 240 nm typically show a long-wavelength tail at >240 nm that is detrimental to the use ...of the devices for skin-friendly antisepsis. We present the development of far-UVC LEDs with reduced long-wavelength emission using a HfO
2
/SiO
2
-based distributed Bragg reflector (DBR) filter. When the DBR filter is directly mounted on an LED package, the long-wavelength emission around 250 nm is reduced by two orders of magnitude while the transmitted output power is reduced down to 18%–27% of the initial value for DBR filters with cut-off wavelengths at 237–243 nm. As the transmission through the DBR filter depends strongly on the angle of incidence of the radiation, the transmitted output power of the spectrally pure far-UVC radiation can be doubled when an additional collimating lens is used on top of the LED package before passing through the filter.
The optical properties of atomically thin transition metal dichalcogenide (TMDC) semiconductors are shaped by the emergence of correlated many-body complexes due to strong Coulomb interaction. ...Exceptional electron-hole exchange predestines TMDCs to study fundamental and applied properties of Coulomb complexes such as valley depolarization of excitons and fine-structure splitting of trions. Biexcitons in these materials are less understood and it has been established only recently that they are spectrally located between exciton and trion. Here we show that biexcitons in monolayer TMDCs exhibit a distinct fine structure on the order of meV due to electron-hole exchange. Ultrafast pump-probe experiments on monolayer WSe\(_2\) reveal decisive biexciton signatures and a fine structure in excellent agreement with a microscopic theory. We provide a pathway to access biexciton spectra with unprecedented accuracy, which is valuable beyond the class of TMDCs, and to understand even higher Coulomb complexes under the influence of electron-hole exchange.
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