bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic gradient and ground penetrating radar prospecting of buried earthen archaeological remains at the Qocho City site in Turpan, China
Authors: Shi Zhanjie , Tian Gang , Hobbs Richard W. , Wo Haowei , Lin Jinxin , Wu Leyuan , Liu Haiyan
Published: September 2015

In order to test the ability of geophysical technologies to detect buried structures made of mud brick and rammed earth, a geophysical survey was acquired at Qocho City site of China in 2012 using magnetic gradient and ground penetrating radar (GPR). Magnetic anomalies were interpreted as the response of house wall foundations, pits, and a temple base by reference to archaeological results from a neighbouring excavation area. The magnetic data were complemented by 2D ground penetrating radar profiles, which provided additional information on the depth of these causative structures. An archaeological survey dated 1913 reported the layout of three houses that have since been largely razed to the ground in the study area. Our geophysical survey confirmed the locations of two houses. This study shows that magnetic and ground penetrating radar methods are valuable tools to detect buried earthen archaeological remains in a dry environment.
A Stromal Cell Niche for Human and Mouse Type 3 Innate Lymphoid Cells
Authors: Hoorweg Kerim , Narang Priyanka , Li Zhi , Thuery Anne , Papazian Natalie , Withers David R. , Coles Mark C. , Cupedo Tom
Published: September 2015

Adaptive immunity critically depends on the functional compartmentalization of secondary lymphoid organs. Mesenchymal stromal cells create and maintain specialized niches that support survival, activation, and expansion of T and B cells, and integrated analysis of lymphocytes and their niche has been instrumental in understanding adaptive immunity. Lymphoid organs are also home to type 3 innate lymphoid cells (ILC3), innate effector cells essential for barrier immunity. However, a specialized stromal niche for ILC3 has not been identified. A novel lineage-tracing approach now identifies a subset of murine fetal lymphoid tissue organizer cells that gives rise exclusively to adult marginal reticular cells. Moreover, both cell types are conserved from mice to humans and colocalize with ILC3 in secondary lymphoid tissues throughout life. In sum, we provide evidence that fetal stromal organizers give rise to adult marginal reticular cells and form a dedicated stromal niche for innate ILC3 in adaptive lymphoid organs.
A Tumor Mitochondria Vaccine Protects against Experimental Renal Cell Carcinoma
Authors: Pierini Stefano , Fang Chongyun , Rafail Stavros , Facciponte John G. , Huang Jialing , De Sanctis Francesco , Morgan Mark A. , Uribe-Herranz Mireia , Tanyi Janos L. , Facciabene Andrea
Published: September 2015

Mitochondria provide energy for cells via oxidative phosphorylation. Reactive oxygen species, a byproduct of this mitochondrial respiration, can damage mitochondrial DNA (mtDNA), and somatic mtDNA mutations have been found in all colorectal, ovarian, breast, urinary bladder, kidney, lung, and pancreatic tumors studied. The resulting altered mitochondrial proteins or tumor-associated mitochondrial Ags (TAMAs) are potentially immunogenic, suggesting that they may be targetable Ags for cancer immunotherapy. In this article, we show that the RENCA tumor cell line harbors TAMAs that can drive an antitumor immune response. We generated a cellular tumor vaccine by pulsing dendritic cells with enriched mitochondrial proteins from RENCA cells. Our dendritic cell–based RENCA mitochondrial lysate vaccine elicited a cytotoxic T cell response in vivo and conferred durable protection against challenge with RENCA cells when used in a prophylactic or therapeutic setting. By sequencing mtDNA from RENCA cells, we identified two mutated molecules: COX1 and ND5. Peptide vaccines generated from mitochondrial-encoded COX1 but not from ND5 had therapeutic properties similar to RENCA mitochondrial protein preparation. Thus, TAMAs can elicit effective antitumor immune responses, potentially providing a new immunotherapeutic strategy to treat cancer.
Deleted in Breast Cancer 1 Suppresses B Cell Activation through RelB and Is Regulated by IKKα Phosphorylation
Authors: Kong Sinyi , Dong Hongxin , Song Jianxun , Thiruppathi Muthusamy , Prabhakar Bellur S. , Qiu Quan , Lin Zhenghong , Chini Eduardo , Zhang Bin , Fang Deyu
Published: September 2015

Alternative NF-κB signaling is crucial for B cell activation and Ig production, and it is mainly regulated by the inhibitor of κ B kinase (IKK) regulatory complex. Dysregulation of alternative NF-κB signaling in B cells could therefore lead to hyperactive B cells and Ig overproduction. In our previous, study we found that deleted in breast cancer 1 (DBC1) is a suppressor of the alternative NF-κB pathway to attenuate B cell activation. In this study, we report that loss of DBC1 results in spontaneous overproduction of Ig in mice after 10 mo of age. Using a double mutant genetic model, we confirm that DBC1 suppresses B cell activation through RelB inhibition. At the molecular level, we show that DBC1 interacts with alternative NF-κB members RelB and p52 through its leucine zipper domain. In addition, phosphorylation of DBC1 at its C terminus by IKKα facilitates its interaction with RelB and IKKα, indicating that DBC1-mediated suppression of alternative NF-κB is regulated by IKKα. Our results define the molecular mechanism of DBC1 inhibition of alternative NF-κB activation in suppressing B cell activation.
Signal Strength and Metabolic Requirements Control Cytokine-Induced Th17 Differentiation of Uncommitted Human T Cells
Authors: Kastirr Ilko , Crosti Mariacristina , Maglie Stefano , Paroni Moira , Steckel Bodo , Moro Monica , Pagani Massimilliano , Abrignani Sergio , Geginat Jens
Published: September 2015

IL-17 production defines Th17 cells, which orchestrate immune responses and autoimmune diseases. Human Th17 cells can be efficiently generated with appropriate cytokines from precommitted precursors, but the requirements of uncommitted T cells are still ill defined. In standard human Th17 cultures, IL-17 production was restricted to CCR6+CD45RA+ T cells, which expressed CD95 and produced IL-17 ex vivo, identifying them as Th17 memory stem cells. Uncommitted naive CD4+ T cells upregulated CCR6, RORC2, and IL-23R expression with Th17-promoting cytokines but in addition required sustained TCR stimulation, late mammalian target of rapamycin (mTOR) activity, and HIF-1α to produce IL-17. However, in standard high-density cultures, nutrients like glucose and amino acids became progressively limiting, and mTOR activity was consequently not sustained, despite ongoing TCR stimulation and T cell proliferation. Sustained, nutrient-dependent mTOR activity also induced spontaneous IL-22 and IFN-γ production, but these cytokines had also unique metabolic requirements. Thus, glucose promoted IL-12–independent Th1 differentiation, whereas aromatic amino acid–derived AHR ligands were selectively required for IL-22 production. The identification of Th17 memory stem cells and the stimulation requirements for induced human Th17/22 differentiation have important implications for T cell biology and for therapies targeting the mTOR pathway.
Adaptive Immunity to Leukemia Is Inhibited by Cross-Reactive Induced Regulatory T Cells
Authors: Manlove Luke S. , Berquam-Vrieze Katherine E. , Pauken Kristen E. , Williams Richard T. , Jenkins Marc K. , Farrar Michael A.
Published: September 2015

BCR-ABL+ acute lymphoblastic leukemia patients have transient responses to current therapies. However, the fusion of BCR to ABL generates a potential leukemia-specific Ag that could be a target for immunotherapy. We demonstrate that the immune system can limit BCR-ABL+ leukemia progression although ultimately this immune response fails. To address how BCR-ABL+ leukemia escapes immune surveillance, we developed a peptide: MHC class II tetramer that labels endogenous BCR-ABL–specific CD4+ T cells. Naive mice harbored a small population of BCR-ABL–specific T cells that proliferated modestly upon immunization. The small number of naive BCR-ABL–specific T cells was due to negative selection in the thymus, which depleted BCR-ABL–specific T cells. Consistent with this observation, we saw that BCR-ABL–specific T cells were cross-reactive with an endogenous peptide derived from ABL. Despite this cross-reactivity, the remaining population of BCR-ABL reactive T cells proliferated upon immunization with the BCR-ABL fusion peptide and adjuvant. In response to BCR-ABL+ leukemia, BCR-ABL–specific T cells proliferated and converted into regulatory T (Treg) cells, a process that was dependent on cross-reactivity with self-antigen, TGF-β1, and MHC class II Ag presentation by leukemic cells. Treg cells were critical for leukemia progression in C57BL/6 mice, as transient Treg cell ablation led to extended survival of leukemic mice. Thus, BCR-ABL+ leukemia actively suppresses antileukemia immune responses by converting cross-reactive leukemia-specific T cells into Treg cells.
Knowledge of diabetes mellitus and its ocular complications amongst diabetic patients attending private and public hospitals in eThekwini Municipality, KwaZulu-Natal province, South Africa
Authors: Van Staden Diane , Deutshmann Luke P. , Ganas Sameer , Manickam Maxine , Manillal Amishka , Ndlovu Nonjabulo S. , Nkosi N. Gugu , Oduntan Olalekan A.
Published: September 2015

Background: The prevalence of Diabetes Mellitus (DM) is increasing in South Africa as a result of changes in lifestyles and rising levels of obesity. Knowledge of management protocols for DM may empower patients to better control the disease and prevent secondary complications.Aim: The aim of this study was to determine if there was a difference in the level of knowledge of DM and its ocular complications amongst public and private hospital diabetic patients.Setting: The study was conducted in four private and four public hospitals in the eThekwini Municipality, KwaZulu-Natal Province.Methods: A cross-sectional survey method was used to collect data from diabetic patients attending selected hospitals. Convenience sampling was used and analysis of descriptive and correlation statistics was done using Statistical Package for Social Sciences (SPSS) version 21.Results: Participants (N = 370) consisted of 44% males and 56% females with 41.6% being from private and 58.4% from public hospitals. The ages of participants ranged from 20 to 79 years. Although most of the participants (74.8%) were knowledgeable about DM and its management, private sector patients were more knowledgeable about DM management than were public sector patients (p = 0.000). Furthermore, private patients had better knowledge of ocular complications related to DM (p = 0.000). Those (74%) who had previously attended a diabetic seminar had significantly better knowledge than those who had not (p = 0.000).Conclusion: Patients with DM attending public hospitals will benefit from targeted education campaigns or seminars related to diabetes and its complications.
Mobilising community-based research on zoonotic infections: A case study of longitudinal cohorts in Vietnam
Authors: Saylors Karen , Ngo Tri Tue , Tran Khanh Toan , Bach Tuan Kiet , Wertheim Heiman FL , Baker Stephen , Ngo Thi Hoa , Bryant Juliet E
Published: September 2015

We initiated the Vietnam Initiative on Zoonotic Infections (VIZIONS) research program to better understand the epidemiology of disease transmission at the human–animal interface in Vietnamese rural communities and to integrate One Health approaches to disease surveillance. We established a longitudinal community cohort study of individuals with occupational exposure to animals, which involves concurrent targeted sampling from domestic livestock species and follow-up monitoring of human clinical cases. The project was implemented by government agencies at the provincial and district levels of the public health and animal health sectors in Vietnam. Engaging with rural communities builds response capacity at the grassroots level, and has improved dialogue between local stakeholders responsible for monitoring human and animal health. Here we describe the process of initiating participatory research and cohort field implementation over the first year in two study sites in Vietnam.Keywords: Vietnam, participatory research, zoonoses, field epidemiology
Shifting the evaluative gaze: Community-based program evaluation in the homeless sector
Authors: Wallace Bruce , Pauly Bernadette , Perkin Kathleen , Ranfft Mike
Published: September 2015

Homelessness is a growing social issue that is a consequence of structural inequities and contributor to the development of health inequities. Community-based research (CBR) has been proposed as an effective research strategy for addressing health equities and promoting social justice through participatory processes. The purpose of this article is to examine the application of CBR principles and practices in the homeless sector and the implications for the production of knowledge and social change to address homelessness. Drawing on our experiences as researchers and service providers, we reflect on the significant successes and challenges associated with using CBR in the homelessness sector. In our discussion we emphasise insights, challenges and lessons learned from a community-university partnership that focused on an evaluation of a transitional shelter program in a large urban centre where housing is expensive and often unavailable.Keywords: Homelessness, housing, transitional housing, transitional shelter, program evaluation, community-based research
Gently, gently: A school-university participatory research partnership in a post-disaster setting
Authors: Mutch Carol , Yates Sarah , Hu Chris
Published: September 2015

In 2010/2011, the city of Christchurch and the surrounding district of Canterbury in New Zealand suffered a series of devastating earthquakes. A study led by The University of Auckland and co-funded by UNESCO followed schools as they came to terms with these events and began to rebuild their lives. The process to recruit and engage schools was slow and respectful as we built trust with first one school, then another. We offered a facilitative and participatory process where each school could choose how they wanted to proceed, who they wanted to involve and what they wanted the outcome to be. We engaged the students in various activities (narratives, video-making and arts-based activities) to help them process the events and move forward. The outcomes included a community mosaic, an illustrated book and video documentaries. This article charts the evolving partnerships between university researchers, school principals, teachers, students and parents. The lessons learned about successful school-university partnerships are summarised under dispositional, relational and situational factors.Keywords: School-university partnership; participatory research; disaster settings; children and young people
A novel recruiting and surveying method: Participatory research during a Pacific Islander community’s traditional cultural event
Authors: Donoho Grace , McElfish Pearl , Avants Rachel , Hallgren Emily
Published: September 2015

Little is known about the health status of Marshallese, a Pacific Islander subpopulation living in the United States. The Marshallese have established a growing community in Northwest Arkansas, providing a unique opportunity for increasing knowledge regarding the health of this minority group. This article describes how a community-based participatory research process was used by a community and university coalition to identify and refine questionnaires and recruit study participants. Questionnaires were self-administered on computers during a one-week traditional cultural event. A total of 874 Marshallese from Arkansas completed the questionnaire, exceeding the goal of 600 respondents. Lessons learned, including the level and timing of involvement of both the leadership and the community at large, are discussed in detail. This approach enhanced communication and collaboration between the Marshallese community, service providers and researchers, resulting in higher participation and interest among the Marshallese community.Keywords: participatory research, minority populations, community health assessment, community coalition, Marshallese
The politics of public engagement – Reclaiming community?
Authors: Clancy Sharon
Published: September 2015

This article examines the tension between the rhetoric and reality of public engagement, seen through the eyes of a practitioner who has worked in both the arenas of community activism and as a public engagement broker within a UK Russell Group university over the course of the last 15 years. This has coincided with the rise to prominence of public engagement as a means of re-energising the debate about the University as an ‘ethical beacon’ and as an agent of civic and social life. This renewed engagement with ‘the public’ has created many powerful research programmes, conferences, debates, resources and toolkits, has fostered organisations and influenced policy. But has it maintained a focus on ‘community’ as a means of understanding and listening to real people, on the ground, and the issues and concerns that animate and concern them? And how far has ‘community’ been squeezed out because it is no longer part of the prevailing political discourse, supplanted by the more broadly interpreted - and possibly more palatable - concept of ‘public’?Suggestions are offered to counter possible ambivalence on the behalf of universities with regard to engaging in ‘deep’ community engagement through both historical and new articulations of adult education and democracy.
What do correlations tell us about anthropogenic–biogenic interactions and SOA formation in the Sacramento Plume during CARES?
Authors: Kleinman L. , Kuang C. , Sedlacek A. , Senum G. , Springston S. , Wang J. , Zhang Q. , Jayne J. , Fast J. , Hubbe J. , Shilling J. , Zaveri R.
Published: September 2015

Abstract. During the Carbonaceous Aerosols and Radiative Effects Study (CARES) the DOE G-1 aircraft was used to sample aerosol and gas phase compounds in the Sacramento, CA plume and surrounding region. We present data from 66 plume transects obtained during 13 flights in which southwesterly winds transported the plume towards the foothills of the Sierra Nevada Mountains. Plume transport occurred partly over land with high isoprene emission rates. Our objective is to empirically determine whether organic aerosol (OA) can be attributed to anthropogenic or biogenic sources, and to determine whether there is a synergistic effect whereby OA concentrations are enhanced by the simultaneous presence of high concentrations of CO and either isoprene, MVK+MACR (sum of methyl vinyl ketone and methacrolein) or methanol, which are taken as tracers of anthropogenic and biogenic emissions, respectively. Linear and bilinear correlations between OA, CO, and each of three biogenic tracers, "Bio", for individual plume transects indicate that most of the variance in OA over short time and distance scales can be explained by CO. For each transect and species a plume perturbation, (i.e., ΔOA, defined as the difference between 90th and 10th percentiles) was defined and regressions done amongst Δ values in order to probe day to day and location dependent variability. Species that predicted the largest fraction of the variance in ΔOA were ΔO3 and ΔCO. Background OA was highly correlated with background methanol and poorly correlated with other tracers. Because background OA was ~ 60 % of peak OA in the urban plume, peak OA should be primarily biogenic and therefore non-fossil. Transects were split into subsets according to the percentile rankings of ΔCO and ΔBio, similar to an approach used by Setyan et al. (2012) and Shilling et al. (2013) to determine if anthropogenic-biogenic interactions enhance OA production. As found earlier, ΔOA in the data subset having high ΔCO and high ΔBio was several-fold greater than in other subsets. Part of this difference is consistent with a synergistic interaction between anthropogenic and biogenic precursors and part to an independent linear dependence of ΔOA on precursors. Highest values of ΔO3 also occur in the high ΔCO–high ΔBio data set, raising the possibility that the coincidence of high concentrations of anthropogenic and biogenic tracers as well as OA and O3 may be associated with high temperatures, clear skies, and poor ventilation in addition to specific interaction between anthropogenic and biogenic compounds.
Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution
Authors: Strada S. , Unger N.
Published: September 2015

Abstract. A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (all anthropogenic, biomass burning and non-biomass burning) are investigated by performing sensitivity experiments. On the global scale, our results show that land carbon fluxes (GPP and isoprene emission) are not sensitive to pollution aerosols, even under a global decline in surface solar radiation (direct + diffuse) by ~ 9 %. At the regional scale, plant productivity (GPP) and isoprene emission show a robust but opposite sensitivity to pollution aerosols, in regions where complex canopies dominate. In eastern North America and Europe, anthropogenic pollution aerosols (mainly from non-biomass burning sources) enhance GPP by +8–12 % on an annual average, with a stronger increase during the growing season (> 12 %). In the Amazon basin and central Africa, biomass burning aerosols increase GPP by +2–5 % on an annual average, with a peak in the Amazon basin during the dry-fire season (+5–8 %). In Europe and China, anthropogenic pollution aerosols drive a decrease in isoprene emission of −2 to −12 % on the annual average. Anthropogenic aerosols affect land carbon fluxes via different mechanisms and we suggest that the dominant mechanism varies across regions: (1) light scattering dominates in the eastern US; (2) cooling in the Amazon basin; and (3) reduction in direct radiation in Europe and China.
A broad supersaturation scanning (BS2) approach for rapid measurement of aerosol particle hygroscopicity and cloud condensation nuclei activity
Authors: Su H. , Cheng Y. , Ma N. , Wang Z. , Wang X. , Pöhlker M. , Nillius B. , Wiedensohler A. , Pöschl U.
Published: September 2015

Abstract. The activation and hygroscopicity of cloud condensation nuclei (CCN) are key to understand aerosol–cloud interactions and their climate impact. It can be measured by scanning the particle size and supersaturation in CCN measurements. The scanning of supersaturation is often time-consuming and limits the temporal resolution and performance of CCN measurements. Here we present a new approach, termed broad supersaturation scanning (BS2) method, in which a range of supersaturation is simultaneously scanned reducing the time interval between different supersaturation scans. The practical applicability of the BS2 approach is demonstrated with nano-CCN measurements of laboratory-generated aerosol particles. Model simulations show that the BS2 approach is also applicable for measuring CCN activation of ambient mixed particles. Due to its fast response and technical simplicity, the BS2 approach may be well suited for long-term measurements. Since hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, a BS2-CCN counter can also serve as a complementary sensor for fast detection/estimation of aerosol chemical compositions.
Carbon monoxide total columns from SCIAMACHY 2.3 μm atmospheric reflectance measurements: towards a full-mission data product (2003–2012)
Authors: Borsdorff T. , Tol P. , Williams J. E. , de Laat J. , aan de Brugh J. , Nédélec P. , Aben I. , Landgraf J.
Published: September 2015

Abstract. We present a full-mission data product of carbon monoxide (CO) vertical column densities using the 2310–2338 nm SCIAMACHY reflectance measurements over clear sky land scenes for the period January 2003–April 2012. The retrieval employs the SICOR algorithm, which will be used for operational data processing of the Sentinel-5 Precursor mission, combined with a SCIAMACHY specific radiometric soft-calibration to mitigate instrumental issues. The retrieval approach infers simultaneously carbon monoxide, methane and water vapour column densities together with a Lambertian surface albedo from individual SCIAMACHY measurements employing a non-scattering radiative transfer model. To account for the radiometric instrument degradation including the formation of an ice-layer on the 2.3 μm detector-array, we consider clear sky measurements over the Sahara as a natural calibration target. For these specific measurements, we spectrally calibrate the SCIAMACHY measurements and determine a spectral radiometric offset and the width of the instrument spectral response function as a function of time for the entire operational phase of the mission. We show that the smoothing error of individual clear sky CO retrievals is less than ±1 ppb and thus this error contribution has not to be accounted for in the validation considering the much higher retrieval noise. The CO data product is validated against measurements of ground-based Fourier transform infrared spectrometers at 27 stations of the NDACC-IRWG and TCCON network and MOZAIC/IAGOS aircraft measurements at 26 airports worldwide. Overall, we find a good agreement with TCCON measurements with a mean bias b = −1.2 ppb and a station-to-station bias with σ = 7.2 ppb. For the NDACC-IRWG network, we obtain a larger mean station bias of b = −9.2 ppb with σ = 8.1 ppb and for the MOZAIC/IAGOS measurements we find b = −6.4 ppb with σ = 5.6 ppb. The SCIAMACHY data set is subject to a small but significant trend of 1.47 ± 0.25 ppb yr−1. After trend correction, the bias with respect to MOZAIC/IAGOS observation is 2.5 ppb, with respect to TCCON measurements it is −4.6 ppb and with respect to NDACC-IRWG measurements −8.4 ppb. Hence, a discrepancy of 3.8 ppb remains between the global biases with NDACC-IRWG and TCCON, which is confirmed by directly comparing NDACC-IRWG and TCCON measurements. Generally, the scatter of the individual SCIAMACHY CO retrievals is high and dominated by large measurement noise. Hence, for practical usage of the dataset, averaging of individual retrievals is required. As an example, we show that monthly mean SCIAMACHY CO retrievals, averaged separately over Northern and Southern Africa, reflect the spatial and temporal variability of biomass burning events in agreement with the global chemical transport model TM5.
In situ evidence of breaking the ion frozen-in condition via the non-gyrotropic pressure effect in magnetic reconnection
Authors: Dai L. , Wang C. , Angelopoulos V. , Glassmeier K.-H.
Published: September 2015

Abstract. For magnetic reconnection to proceed, the frozen-in condition for both ion fluid and electron fluid in a localized diffusion region must be violated by inertial effects, thermal pressure effects, or inter-species collisions. It has been unclear which underlying effects unfreeze ion fluid in the diffusion region. By analyzing in situ THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft measurements at the dayside magnetopause, we present clear evidence that the off-diagonal components of the ion pressure tensor is mainly responsible for breaking the ion frozen-in condition in reconnection. The off-diagonal pressure tensor, which corresponds to a non-gyrotropic pressure effect in this event, is a fluid manifestation of ion demagnetization in the diffusion region. From the perspective of the ion momentum equation, the reported non-gyrotropic ion pressure tensor is a fundamental aspect in specifying the reconnection electric field that controls how quickly reconnection proceeds.
Latitudinal and temporal distributions of diatom populations in the pelagic waters of the Subantarctic and Polar Frontal zones of the Southern Ocean and their role in the biological pump
Authors: Rigual-Hernández A. S. , Trull T. W. , Bray S. G. , Cortina A. , Armand L. K.
Published: September 2015

Abstract. The Subantarctic and Polar Frontal zones (SAZ and PFZ) represent a large portion of the total area of the Southern Ocean and serve as a strong sink for atmospheric CO2. These regions are central to hypotheses linking particle fluxes and climate change, yet multi-year records of modern flux and the organisms that control it are, for obvious reasons, rare. In this study, we examine two sediment trap records of the flux of diatoms and bulk components collected by two bottom-tethered sediment traps deployed at mesopelagic depths (~ 1 km) in the SAZ (2-year record; July 1999–October 2001) and in the PFZ (6-year record; September 1997–February 1998, July 1999–August 2000, November 2002–October 2004 and December 2005–October 2007) along the 140° E meridian. These traps provide a direct measure of transfer below winter mixed layer depths, i.e. at depths where effective sequestration from the atmosphere occurs, in contrast to study of processes in the surface ocean. Total mass fluxes were about twofold higher in the PFZ (24 ± 13 g m−2 yr−1) than in the SAZ (14 ± 2 g m−2 yr−1). Bulk chemical composition of the particle fluxes mirrored the composition of the distinct plankton communities of the surface layer, being dominated by carbonate in the SAZ and by biogenic silica in the PFZ. Particulate organic carbon (POC) export was similar for the annual average at both sites (1.0 ± 0.1 and 0.8 ± 0.4 g m−2 yr−1 for the PFZ and SAZ, respectively), indicating that the particles in the SAZ were relatively POC rich. Seasonality in the particle export was more pronounced in the PFZ. Peak fluxes occurred during summer in the PFZ and during spring in the SAZ. The strong summer pulses in the PFZ are responsible for a large fraction of the variability in carbon sequestration from the atmosphere in this region. The latitudinal variation of the total diatom flux was found to be in line with the biogenic silica export with an annual flux of 31 ± 5.5 × 108 valves m−2 yr−1 at the PFZ compared to 0.5 ± 0.4 × 108 m−2 yr−1 at the SAZ. Fragilariopsis kerguelensis dominated the annual diatom export at both sites (43 % at the SAZ and 59 % in the PFZ). POC fluxes displayed a strong positive correlation with the relative contribution of a group of weakly silicified and bloom-forming species in the PFZ. Several lines of evidence suggests that the development of these species during the growth season facilitates the formation of aggregates and carbon export. Our results confirm previous work suggesting that F. kerguelensis plays a major role in the decoupling of the carbon and silicon cycles in the high-nutrient low-chlorophyll waters of the Southern Ocean.
Tree water relations can trigger monoterpene emissions from Scots pine stems during spring recovery
Authors: Vanhatalo A. , Chan T. , Aalto J. , Korhonen J. F. , Kolari P. , Hölttä T. , Nikinmaa E. , Bäck J.
Published: September 2015

Abstract. Tree canopies are known to emit large amounts of VOCs (volatile organic compounds) such as monoterpenes into the surrounding air. High VOC emission rates from boreal forests have been observed during the transition from winter to summer activity. The most important sources of these are considered to be the green foliage, understory vegetation and soil organisms, but emissions from the living stand woody compartments have so far not been quantified. We analyzed whether the non-foliar components could partially explain the springtime high emission rates. We measured the monoterpene emissions from Scots pine (Pinus sylvestris L.) stem and shoots during the dehardening phase of trees in field conditions in two consecutive springs. We observed a large, transient monoterpene burst from the stem, while the shoot monoterpene emissions remained low. The burst lasted about 12 h. Simultaneously, an unusual nighttime sap flow and a non-systematic diurnal pattern of tree diameter were detected. Hence, we suggest that the monoterpene burst was a consequence of the recovery of the stem from wintertime, and likely related to the refilling of embolized tracheids and/or phenological changes in the living cells of the stem. This indicates that the dominant processes and environmental drivers triggering the monoterpene emissions are different between the stem and the foliage.
Comment on "Solute-specific scaling of inorganic nitrogen and phosphorus uptake in streams" by Hall et al. (2013)
Authors: González-Pinzón R. , Mortensen J. , Van Horn D.
Published: September 2015

Abstract. Hall et al. (2013) presented a synthesis on 969 nutrient tracer experiments conducted primarily in headwater streams (generally < fourth-order streams), with discharges < 200 L s−1 for ~90 % of the experiments, and used a scaling method to test the hypothesis that nutrient demand is constant with increasing stream size (i.e., along a river continuum). In this comment we present a reanalysis of a subset of the data used by Hall et al. (2013) and propose that their correlations between nutrient uptake lengths of ecologically important solutes and specific discharge are inadvertently spurious. Therefore, the conclusions derived from such correlations are debatable. We conclude the comment by highlighting some of the uncertainties associated with using modeling frameworks for scaling nutrient uptake in stream ecosystems.
Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments
Authors: Thomas Z. , Abbott B. W. , Troccaz O. , Baudry J. , Pinay G.
Published: September 2015

Abstract. Direct and indirect effects from agriculture, urbanization, and resource extraction have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. The capacity of a watershed to remove or retain nutrients is a function of biotic and abiotic conditions across the terrestrial-aquatic gradient including soil, groundwater, riparian zone, and surface water. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments. We analysed a five-year, high frequency water chemistry dataset from 3 catchments ranging from 2.3 to 10.8 km2 in northwestern France. Catchments differed in the relationship between hydrology and solute concentrations, associated with catchment characteristics such as hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness appeared to have greater transient storage and residence time, buffering the catchment to fluctuations in water chemistry, reflected in relatively invariant carbon and nutrient chemistry across hydrologic conditions. Conversely, the catchments with smoother, thinner soils responded to both intra- and inter-annual hydrologic variation with high concentrations of PO43− and NH4+ during low flow conditions and strong increases in DOC, sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land use) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on elemental fluxes is both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent catchment buffering capacity and probability of human disturbance provides a useful perspective for evaluating vulnerability of aquatic ecosystems to human disturbance.
Evidence of old soil carbon in grass biosilica particles
Authors: Reyerson P. E. , Alexandre A. , Harutyunyan A. , Corbineau R. , Martinez De La Torre H. A. , Badeck F. , Cattivelli L. , Santos G. M.
Published: September 2015

Abstract. Plant biosilica particles (phytoliths) contain small amounts of carbon called phytC. Based on the assumptions that phytC is of photosynthetic origin and a closed system, claims were recently made that phytoliths from grasslands play a significant role in atmospheric CO2 sequestration. However, anomalous phytC radiocarbon (14C) dates suggested contributions from a non-photosynthetic source to phytC. Here we address this non-photosynthetic source hypothesis using comparative isotopic measurements (14C and δ13C) of phytC, plant tissues, atmospheric CO2, and soil organic matter. State-of-the-art methods assured phytolith purity, while sequential stepwise-combustion revealed complex chemical–thermal decomposability properties of phytC. Although photosynthesis is the main source of carbon in plant tissue, it is found that phytC is partially derived from soil carbon that can be several thousand years old. The accumulation of old soil organic matter derived carbon in plant biosilica suggests that Si absorption and phytolith production promote old soil organic carbon mobilization. Although the magnitude of this mechanism still needs to be properly assessed at plant and ecosystem scales, its confirmation alone argues against attempts to use phytC as a proxy of plant carbon and call for the reexamination of phytolith atmospheric CO2 biosequestration estimates.
First tephrostratigraphic results of the DEEP site record from Lake Ohrid, Macedonia
Authors: Leicher N. , Zanchetta G. , Sulpizio R. , Giaccio B. , Wagner B. , Nomade S. , Francke A. , Del Carlo P.
Published: September 2015

Abstract. A~tephrostratigraphic record covering the Marine Isotope Stages (MIS) 1–15 was established for the DEEP site record of Lake Ohrid (Macedonia/Albania). Major element analyses (SEM-EDS/WDS) were carried out on juvenile fragments extracted from 12 tephra layers (OH-DP-0115 to OH-DP-2060). The geochemical analyses of the glass shards of all of these layers suggest an origin from the Italian Volcanic Provinces. They include: the Y-3 (OH-DP-0115, 26.68–29.42 cal ka BP), the Campanian Ignimbrite/Y-5 (OH-DP-0169, 39.6 ± 0.1 ka), and the X-6 (OH-DP-0404, 109 ± 2 ka) from the Campanian volcanoes, the P-11 of the Pantelleria Island (OH-DP-0499, 129 ± 6 ka), the Vico B (OH-DP-0617, 162 ± 6 ka) from the Vico volcano, the Pozzolane Rosse (OH-DP-1817, 457 ± 2 ka) and the Tufo di Bagni Albule (OH-DP-2060, 527 ± 2 ka) from the Colli Albani volcanic district, and the Fall A (OH-DP-2010, 496 ± 3 ka) from the Sabatini volcanic field. Furthermore, a comparison of the Ohrid record with tephrostratigraphic records of mid-distal archives related to the Mediterranean area, allowed the recognition of the equivalents of other less known tephra layers, such as the TM24-a/POP2 (OH-DP-0404, 101.8 ka) from the Lago Grande di Monticchio and the Sulmona basin, the CF-V5/PRAD3225 (OH-DP-0624, ca. 162 ka) from the Campo Felice basin/Adriatic Sea, the SC5 (OH-DP-1955, 493.1 ± 10.9 ka) from the Mercure basin, and the A11/12 (OH-DP-2017, 511 ± 6 ka) from the Acerno basin, whose specific volcanic sources are still poorly constrained. Additionally, one cryptotephra (OH-DP-0027) was identified by correlation of the potassium XRF intensities from the DEEP site with those from short cores of previous studies from Lake Ohrid. In these cores, a maximum in potassium is caused by glass shards, which were correlated with the Mercato tephra (8.43–8.63 cal ka BP) from Somma-Vesuvius. With the tephrostratigraphic work, a consistent part of the Middle Pleistocene tephrostratigraphic framework of Italian volcanoes was for the first time extended as far as to the Balkans. The establishment of the tephrostratigraphic framework for the Lake Ohrid record provides important, independent tie-points for the age-depth model of the DEEP site sequence, which is a prerequisite for paleoclimatic and -environmental reconstructions. Furthermore, this age-depth model will help to improve and re-evaluate the chronology of other, both undated and dated tephra layers from other records. Thus, the Lake Ohrid record is candidate to become the Rosetta stone for the central Mediterranean tephrostratigraphy, especially for the hitherto poorly known and explored lower Middle Pleistocene period.
Pollen-based paleoenvironmental and paleoclimatic change at Lake Ohrid (SE Europe) during the past 500 ka
Authors: Sadori L. , Koutsodendris A. , Masi A. , Bertini A. , Combourieu-Nebout N. , Francke A. , Kouli K. , Joannin S. , Mercuri A. M. , Panagiotopoulos K. , Peyron O. , Torri P. , Wagner B. , Zanchetta G. , Donders T. H.
Published: September 2015

Abstract. Lake Ohrid is located at the border between FYROM and Albania and formed during the latest phases of Alpine orogenesis. It is the deepest, the largest and the oldest tectonic lake in Europe. To better understand the paleoclimatic and paleoenvironmental evolution of Lake Ohrid a deep drilling was carried out in 2013 within the framework of the Scientific Collaboration on Past Speciation Conditions (SCOPSCO) project that was funded by the International Continental Drilling Program (ICDP). Preliminary results indicate that lacustrine sedimentation of Lake Ohrid started between 1.2 and 1.9 Ma ago. Here we present new pollen data (selected percentage and concentration taxa/groups) of the uppermost ~200 m of the 569 m-long DEEP core drilled in the depocenter of Lake Ohrid. The study is the fruit of a cooperative work carried out in several European palynological laboratories. The age model is based on nine tephra layers and on tuning of biogeochemical proxy data to orbital parameters and to the global benthic isotope stack LR04. According to the age model the studied sequence covers the last ~500 000 years at a millennial-scale resolution (~1.6 ka) and record the major vegetation and climate changes that occurred during the last 12 (13 only pro parte) marine isotope stages (MIS). Our results indicate that there is a general good correspondence between forested/non-forested periods and glacial/interglacial cycles of marine isotope stratigraphy. Our record shows a progressive change from cooler and wetter to warmer and dryer interglacial conditions. This shift is visible also in glacial vegetation. The interglacial phase corresponding to MIS11 (pollen assemblage zone, PAZ OD-12, 488–455 ka BP and OD-19, 367–328 ka BP) is dominated by montane trees such as conifers. The two younger interglacial periods, MIS5 (PAZ OD-3, 126–70 ka BP) and MIS1 (PAZ OD-1, 12 ka BP to present) are marked by dominance of mesophilous elements such as deciduous and semi-deciduous oaks. Moreover, MIS7 (PAZ OD-6, 245–189 ka) shows a very high interglacial variability, with alternating expansions of montane and mesophilous arboreal taxa. Grasslands (open vegetation formations requiring relatively humid conditions) characterize the first glacial phases of MIS12 (PAZ OD-12, 488–455 ka), MIS10 (corresponding to PAZ OD-10, 421–367 ka) and MIS8 (PAZ OD-7, 285–245 ka). Steppes (open vegetation formations typical of dry environments) prevail during MIS6 (OD-5 and OD-4, 189–126 ka) and during MIS4–2 (PAZ OD-2, 70–12 ka). Our palynological results support the notion that Lake Ohrid has been a refugium area for both temperate and montane trees during glacials. Close comparisons with other long southern European and Near Eastern pollen records will be achieved through ongoing high-resolution studies.
A millennial summer temperature reconstruction for northeastern Canada using oxygen isotopes in subfossil trees
Authors: Naulier M. , Savard M. M. , Bégin C. , Gennaretti F. , Arseneault D. , Marion J. , Nicault A. , Bégin Y.
Published: September 2015

Abstract. Climatic reconstructions for northeastern Canada are scarce such that this area is under-represented in global temperature reconstructions. To fill this lack of knowledge and identify the most important processes influencing climate variability, this study presents the first summer temperature reconstruction for eastern Canada based on a millennial oxygen isotopic series (δ18O) from tree rings. For this purpose, we selected 230 well-preserved subfossil stems from the bottom of a boreal lake and five living trees on the lakeshore. The sampling method permitted an annually resolved δ18O series with a replication of five trees per year. The June to August maximal temperature of the last millennium has been reconstructed using the statistical relation between Climatic Research Unit (CRU TS3.1) and δ18O data. The resulting millennial series is marked by the well-defined Medieval Climate Anomaly (MCA; AD 1000–1250), the Little Ice Age (AD 1450–1880) and the modern period (AD 1950–2010), and an overall average cooling trend of −0.6 °C millennium−1. These climatic periods and climatic low-frequency trends are in agreement with the only reconstruction available for northeastern Canada and others from nearby regions (Arctic, Baffin Bay) as well as some remote regions like the Canadian Rockies or Fennoscandia. Our temperature reconstruction indicates that the Medieval Climate Anomaly was characterized by a temperature range similar to the one of the modern period in the study region. However, the temperature increase during the last 3 decades is one of the fastest warming observed over the last millennium (+1.9 °C between 1970–2000). An additional key finding of this research is that the coldest episodes mainly coincide with low solar activities and the extremely cold period of the early 19th century has occurred when a solar minimum was in phase with successive intense volcanic eruptions. Our study provides a new perspective unraveling key mechanisms that controlled the past climate shifts in northeastern Canada.
Impact of ice sheet meltwater fluxes on the climate evolution at the onset of the Last Interglacial
Authors: Goelzer H. , Huybrechts P. , Loutre M.-F. , Fichefet T.
Published: September 2015

Abstract. Large climate perturbations occurred during Termination II when the ice sheets retreated from their glacial configuration. Here we investigate the impact of ice sheet changes and associated freshwater fluxes on the climate evolution at the onset of the Last Interglacial. The period from 135 to 120 kyr BP is simulated with the Earth system model of intermediate complexity LOVECLIM v.1.3 with prescribed evolution of the Antarctic ice sheet, the Greenland ice sheet and the other Northern Hemisphere ice sheets. Variations in meltwater fluxes from the Northern Hemisphere ice sheets lead to North Atlantic temperature changes and modifications of the strength of the Atlantic meridional overturning circulation. By means of the interhemispheric see-saw effect, variations in the Atlantic meridional overturning circulation also give rise to temperature changes in the Southern Hemisphere, which are modulated by the direct impact of Antarctic meltwater fluxes into the Southern Ocean. Freshwater fluxes from the melting Antarctic ice sheet lead to a millennial time scale oceanic cold event in the Southern Ocean with expanded sea ice as evidenced in some ocean sediment cores, which may be used to constrain the timing of ice sheet retreat.