Divergent drivers of the microbial methane sink in temperate forest and grassland soils

Aerated topsoils are important sinks for atmospheric methane (CH4) via oxidation by CH4‐oxidizing bacteria (MOB). However, intensified management of grasslands and forests may reduce the CH4 sink capacity of soils. We investigated the influence of grassland land‐use intensity (150 sites) and forest management type (149 sites) on potential atmospheric CH4 oxidation rates (PMORs) and the abundance and diversity of MOB (with qPCR) in topsoils of three temperate regions in Germany. PMORs measurements in microcosms under defined conditions yielded approximately twice as much CH4 oxidation in forest than in grassland soils. High land‐use intensity of grasslands had a negative effect on PMORs (−40%) in almost all regions and fertilization was the predominant factor of grassland land‐use intensity leading to PMOR reduction by 20%. In contrast, forest management did not affect PMORs in forest soils. Upland soil cluster (USC)‐α was the dominant group of MOBs in the forests. In contrast, USC‐γ was absent in more than half of the forest soils but present in almost all grassland soils. USC‐α abundance had a direct positive effect on PMOR in forest, while in grasslands USC‐α and USC‐γ abundance affected PMOR positively with a more pronounced contribution of USC‐γ than USC‐α. Soil bulk density negatively influenced PMOR in both forests and grasslands. We further found that the response of the PMORs to pH, soil texture, soil water holding capacity and organic carbon and nitrogen content differ between temperate forest and grassland soils. pH had no direct effects on PMOR, but indirect ones via the MOB abundances, showing a negative effect on USC‐α, and a positive on USC‐γ abundance. We conclude that reduction in grassland land‐use intensity and afforestation has the potential to increase the CH4 sink function of soils and that different parameters determine the microbial methane sink in forest and grassland soils.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659ESFMinistry of Education, Science and Culture of Mecklenburg‐Western PomeraniaPeer Reviewe

Prosthetic Knee for CURE Kenya

Lower limb amputations are common in sub-Saharan Africa due to the prevalence of disease and infection in communities that lack access to adequate healthcare. Our project, Prosthetic Knee, partners with the CURE International Hospital in Kijabe, Kenya. In the region surrounding our client’s facility, there is a large number of lower-extremity amputations due to various infections and diseases. While many of these amputees only require a through-knee amputation, the lack of an affordable through-knee prosthesis often forces patients to undergo a more invasive transfemoral amputation to enable them to use a cheaper above-knee prosthesis. The goal of our project is to design and manufacture a financially accessible and user-friendly prosthetic knee for knee-disarticulation patients that can be manufactured in Messiah University’s machine shop (and ultimately, at the orthopedic facility in Kijabe). This year, the team’s work has included finalizing the prototype design, conducting finite element analysis in SOLIDWORKS to evaluate the knee’s static and fatigue strength, and beginning the process of physical manufacturing. Additionally, a damping mechanism driven by a spring-loaded system has been developed and integrated into the design after completing motion analysis and SOLIDWORKS modeling. Our future goals include manufacturing a complete metal prototype of the knee, conducting physical strength and fatigue testing on the metal prototype, and continuing iterative prototyping of the damper in preparation for physical implementation.https://mosaic.messiah.edu/engr2021/1014/thumbnail.jp

DNA-dependent Protein Kinase Activity Is Not Required for Immunoglobulin Class Switching

Class switch recombination (CSR), similar to V(D)J recombination, is thought to involve DNA double strand breaks and repair by the nonhomologous end–joining pathway. A key component of this pathway is DNA-dependent protein kinase (DNA-PK), consisting of a catalytic subunit (DNA-PKcs) and a DNA-binding heterodimer (Ku70/80). To test whether DNA-PKcs activity is essential for CSR, we examined whether IgM+ B cells from scid mice with site-directed H and L chain transgenes were able to undergo CSR. Although B cells from these mice were shown to lack DNA-PKcs activity, they were able to switch from IgM to IgG or IgA with close to the same efficiency as B cells from control transgenic and nontransgenic scid/+ mice, heterozygous for the scid mutation. We conclude that CSR, unlike V(D)J recombination, can readily occur in the absence of DNA-PKcs activity. We suggest nonhomologous end joining may not be the (primary or only) mechanism used to repair DNA breaks during CSR

Prosthetic Knee for CURE Kenya: Design and Manufacturing

The Prosthetic Knee team is partnered with the CURE International Hospital in Kijabe, Kenya. In the region surrounding our client’s facility, there is a large number of lower-extremity amputations due to various infections and diseases. Often, these patients choose to undergo a more invasive transfemoral amputation to enable them to use a less expensive above-knee prosthesis. The goal of the project is to present the orthopedic workshop at CURE with a manufacturable prosthetic knee design in May of 2023 that provides through-knee amputee patients with a more affordable, aesthetically pleasing, and lightweight prosthetic option, thereby removing the need to undergo an additional amputation above the knee. The poster presents the overarching elements of the prosthetic design in addition to the recently integrated locking and damping components, which aid in the functionality of the knee. Funding for this work provided by The Collaboratory for Strategic Partnerships and Applied Research.https://mosaic.messiah.edu/engr2022/1013/thumbnail.jp

The Active Assembly of the Virgo Cluster: Indications for Recent Group Infall From Early-type Dwarf Galaxies

Virgo is a dynamically young galaxy cluster with substructure in its spatial and kinematic distribution. Here we simultaneously study the phase-space distribution and the main characteristics of Virgo's galaxies, particularly its most abundant galaxy population-the early-type dwarfs-to understand their environmental transformation histories. Aside from known correlations with morphological types-like the larger average clustercentric distance of late-type galaxies-we find an intriguing behavior of early types with magnitudes -17 >= Mr >= -18. They show a large velocity spread and an asymmetric phase-space distribution, similar to the late-type galaxies and different from the early types just 1 mag brighter/fainter. Furthermore, we find a close phase-space aggregation of early-type dwarfs at large clustercentric distance and high relative velocity. Nearly all of them show signatures of disk components, and their colors imply stellar ages that are younger than the population average. They are not located closely together but spread azimuthally around the cluster center. We show that this is expected from simulations of an infalling galaxy group that slowly gets dispersed after its first pericentric passage. We thus conclude that these galaxies are recent arrivals and that the peculiar phase-space distribution of early-type dwarfs is evidence for the ongoing growth of this galaxy population. Studying galaxies based on their phase-space correlations is a unique way to compare the properties of recent and older cluster members and to understand which environment most influenced their present-day characteristics

Comparison of the transcriptional landscapes between human and mouse tissues

Although the similarities between humans and mice are typically highlighted, morphologically and genetically, there are many differences. To better understand these two species on a molecular level, we performed a comparison of the expression profiles of 15 tissues by deep RNA sequencing and examined the similarities and differences in the transcriptome for both protein-coding and -noncoding transcripts. Although commonalities are evident in the expression of tissue-specific genes between the two species, the expression for many sets of genes was found to be more similar in different tissues within the same species than between species. These findings were further corroborated by associated epigenetic histone mark analyses. We also find that many noncoding transcripts are expressed at a low level and are not detectable at appreciable levels across individuals. Moreover, the majority lack obvious sequence homologs between species, even when we restrict our attention to those which are most highly reproducible across biological replicates. Overall, our results indicate that there is considerable RNA expression diversity between humans and mice, well beyond what was described previously, likely reflecting the fundamental physiological differences between these two organisms

Photocurrent measurements of supercollision cooling in graphene

The cooling of hot electrons in graphene is the critical process underlying the operation of exciting new graphene-based optoelectronic and plasmonic devices, but the nature of this cooling is controversial. We extract the hot electron cooling rate near the Fermi level by using graphene as novel photothermal thermometer that measures the electron temperature ($T(t)$) as it cools dynamically. We find the photocurrent generated from graphene $p-n$ junctions is well described by the energy dissipation rate $C dT/dt=-A(T^3-T_l^3)$, where the heat capacity is $C=\alpha T$ and $T_l$ is the base lattice temperature. These results are in disagreement with predictions of electron-phonon emission in a disorder-free graphene system, but in excellent quantitative agreement with recent predictions of a disorder-enhanced supercollision (SC) cooling mechanism. We find that the SC model provides a complete and unified picture of energy loss near the Fermi level over the wide range of electronic (15 to $\sim$3000 K) and lattice (10 to 295 K) temperatures investigated.Comment: 7pages, 5 figure