Resolved diffraction patterns from a reflection grating for atoms

We have studied atomic diffraction at normal incidence from an evanescent standing wave with a high resolution using velocity selective Raman transitions. We have observed up to 3 resolved orders of diffraction, which are well accounted for by a scalar diffraction theory. In our experiment the transverse coherence length of the source is greater than the period of the diffraction grating.Comment: 8 pages, 4 figure

Assessing neurotoxicity from the low-dose radiation component of radiosurgery using magnetic resonance spectroscopy

The aim of the study was to determine if biochemical changes indicative of injury, assessed using magnetic resonance spectroscopic imaging (SI), are observed after stereotactic radiosurgery (SRS). The study included patients who underwent SI immediately before and 1, 30, and 90 days following SRS. Short TE spectra (TR/TE 1000/35 ms) were acquired at the SRS isocenter with a 2D PRESS-CSI sequence on a single 1.5 T scanner. The SRS isodose lines were overlaid on the magnetic resonance imaging slice utilized for SI data acquisition. N-Acetyl aspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were computed for multiple voxels located between the 25 and 50 cGy isodose lines (low dose) and the 200 and 350 cGy isodose lines (medium dose). An analysis of variance and paired t-tests compared metabolite levels at different time points. Twelve patients were enrolled, although 3 were excluded secondary to poor spectral data quality or deviations from the prescribed SI protocol. The median number of voxels analyzed from the low- and medium-dose region was 7 and 4, respectively. No significant changes in metabolite peak height ratios over time were seen in the low-dose region, for either NAA/Cr (P = .89) or Cho/Cr (P = .85). There was no difference in Cho/Cr peak height ratios in the medium-dose region (P = .62). There was an increase in the NAA/Cr peak height ratio in the medium-dose region between day −1 and day +30 (P = .003), followed by a decline to baseline between days +30 and +90 (P = .03). We did not observe a significant decline in NAA/Cr or change in Cho/Cr peak heights in uninvolved brain parenchyma after SRS

Weaving ways of knowing to enhance biocultural resilience in a mahinga kai species-at-risk

The futures of many threatened species rest on our collective efforts to reweave the biological, cultural, and linguistic threads that together comprise biocultural diversity. For Western researchers, there is growing recognition that Indigenous Peoples and local communities are at the forefront of place-based approaches that bring together diverse ways of knowing and seeing. Here in Aotearoa New Zealand, these include restoration efforts led by mana whenua tribal groups with local authority to weave Māori—the Indigenous Peoples of Aotearoa New Zealand—knowledge, practices, and processes with Western science. For example, genomic markers offer a unique lens to explore relationships across populations, and in turn, co-develop management programmes that build resilience in threatened species. A growing number of studies are applying genomic data to enhance conservation outcomes, but few have tapped into their full potential by weaving these data with Indigenous and local relationships of place. This thesis represents the collective efforts of many—including whānau extended families, researchers, and practitioners, many of whom affiliate to the local iwi tribe, Ngāi Tahu—led here by a Pākehā (New Zealander of European settler descent) researcher. The recent application of genomic tools by Western-trained researchers to address conservation issues (i.e., conservation genomics) presents both opportunities and challenges for efforts to restore biocultural diversity. This thesis seeks to consider such complexities, including how genomic data might be better understood through a multiplicity of worldviews. Chapter Two serves to frame the research narrative of this thesis through a Perspective published in People and Nature’s joint special issue on informing decision-making with Indigenous and local knowledge and science. Few published conservation translocations (i.e., movement of animals or plants for conservation benefit) are led or co-led by Indigenous Peoples or centre Indigenous knowledge systems. As Kāi Tahu and Pākehā researchers and practitioners working in partnership in Aotearoa New Zealand, we consider how conservation translocations that weave diverse ways of knowing and seeing can enhance species recovery and build ecosystem resilience. We highlight the co-development of conservation translocations with Te Kōhaka o Tūhaitara and Te Nohoaka o Tukiauau Trusts where we are weaving emerging genomic approaches with mātauraka Māori Māori knowledge systems to recover culturally significant freshwater species. We further offer a Two-Eyed Seeing framework to support the co- design of conservation translocations led or co-led by Indigenous researchers and communities around the world. Chapter Three extends the narrative introduced in Chapter Two by focusing on the caveats of interpreting genomic data without local historical or contemporary context; namely, the movement or management of culturally significant species by Indigenous Peoples and local communities (IPLCs) in the distant or recent past. This Perspective brings together Kāi Tahu and Pākehā researchers and practitioners with expertise across customary and contemporary mahika kai food gathering (i.e., including processes, practices, and places), conservation genomics, ecology, fish biology, and aquaculture. To date, few efforts to characterise genetic variation within and between populations consider how human relationships with place may shape present-day species distributions. Yet, the movement of species by Indigenous and local communities in the distant and recent past provides important context for the interpretation of genomic data. For example, freshwater kōura1 crayfish in subalpine streams alongside ancient walking trails in Te Waipounamu (the South Island of Aotearoa New Zealand) were moved between sites to provide readily accessible food for travellers. We reflect on how weaving diverse ways of knowing and seeing can better reveal the biocultural complexities of genomic data derived from culturally significant species such as kōura, including locally adaptive variation. In Chapter Four, we shift focus to a research partnership with aquaculture company KEEWAI, mana whenua, and Te Rūnanga o Ngāi Tahu (TRoNT). This chapter reflects on the benefits, risks, and outstanding questions around genetic rescue (i.e., the introduction or restoration of new genetic material to small, isolated populations to reduce genetic load). We present experimental co-design and preliminary genomic data as proof-of-concept for a series of kōura translocation experiments at the KEEWAI aquaculture ponds ultimately intended to grow our understanding of the genetic mechanisms underlying genetic rescue. These data contribute toward the foundation and development of a multi-generational research programme that will support tribal-led aquaculture initiatives for kōura and other mahika kai species across the Kāi Tahu takiwā tribal territory. The research partnerships and approaches described above are brought together in Chapter Five to explore contemporary and historical relationships across kēkēwai1 freshwater crayfish populations in Te Waipounamu by weaving genomic data with placed-based knowledges. Genomic data reveal strong population genetic structure—as well as signatures of population admixture—across seventeen genetically depauperate populations in Te Waipounamu. Differentiation and environment association analyses further identify patterns of genetic variation linked to hydroclimatic variables, including temperature, precipitation, and water flow regimes. We consider how weaving these data with place-based knowledges can enhance resilience in kēkēwai through tribal-led initiatives for mahika kai. Our findings further contribute toward a growing understanding of how adaptive and neutral genetic variation shape threatened species’ capacity to respond to future change. Finally, Chapter Six critically reflects on the journey of this thesis and future directions, including tribal-led research programmes that will strengthen the relationships between people and mahika kai to build intergenerational capacity for protecting biocultural heritage. Two additional manuscripts, three blogs and an example summary for mana whenua are also included in the appendices. Together, these works contribute toward reconnection to place and the growth of our collective knowledge for treasured species in Aotearoa New Zealand and beyond