Bell Beaker ‘Re-Use’ of Older Sites

In Western and West-Central Europe, it is common to find sherds of Bell-Beakers in the uppermost layers of megalithic monuments, sometimes accompanied by bones of a corre- sponding age. This ‘re-use’ is not restricted to burial-context. Henges and stone circles can contain so-called ‘coves’ from the Bell Beaker period. This points to a changed use of the structure. The most famous example is Stonehenge. I interpret this as a deliberate attempt by a new elite to erase power-mechanisms of previous generations. The effort put into these acts shows that these structures were perceived as a real threat to the new order. This case study illustrates the difficulty of distinguishing between different ways of using the past, between the use and the intended destruction of memorie

Salt, fire, cress and fennel – how to create pollution

This article reflects on the concept of pollution as a concept and its history from an anthropological-archaeological perspective. With reference to Mary Douglas, the peculiarities of the archaeological approach to the concept are explained. The context of pollution is illuminated as an interpretative category by historical and ethnological case studies

Mapping Memory, Space and Conflict

Our introduction to the volume sets the discussion about memory in archaeology into current contexts, establishes our reasons for producing this book and discusses a number of crucial aspects of memory, space, and identity. We provide a brief history of memory studies with a focus on contributions from archaeology and discuss a number of topics that play important roles in the papers. These include the relations between forgetting and remem- bering, and between space, place and memory. Along with our authors, we emphasize that memory is a matter of practices, not just of mindsets. A further element in our discussions is the interface between memory, duration, and history. All of these issues coalesce in an important background theme, the political nature of various modes of memor

The importance of phytoplankton trait variability in spring bloom formation

About 60 years ago, the critical depth hypothesis was proposed to describe the occurrence of spring phytoplankton blooms and emphasized the role of stratification for the timing of onset. Since then, several alternative hypotheses appeared focusing on the role of grazing and mixing processes such as turbulent convection or wind activity. Surprisingly, the role of community composition—and thus the distribution of phytoplankton traits—for bloom formation has not been addressed. Here, we discuss how trait variability between competing species might influence phytoplankton growth during the onset of the spring bloom. We hypothesize that the bloom will only occur if there are species with a combination of traits fitting to the environmental conditions at the respective location and time. The basic traits for formation of the typical spring bloom are high growth rates and photoadaptation to low light conditions, but other traits such as nutrient kinetics and grazing resistance might also be important. We present concise ideas on how to test our theoretical considerations experimentally. Furthermore, we suggest that future models of phytoplankton blooms should include both water column dynamics and variability of phytoplankton traits to make realistic projections instead of treating the phytoplankton bloom as an aggregate community phenomenon

Portal vein embolization using a Histoacryl/Lipiodol mixture before right liver resection

Purpose: The purpose of this retrospective study was to evaluate the efficacy and safety of percutaneous transhepatic portal vein embolization (PVE) of the right liver lobe using Histoacryl/Lipiodol mixture to induce contralateral liver hypertrophy before right-sided (or extended right-sided) hepatectomy in patients with primarily unresectable liver tumors. Methods: Twenty-one patients (9 females and 12 males) underwent PVE due to an insufficient future liver remnant; 17 showed liver metastases and 4 suffered from biliary cancer. Imaging was performed prior to and 4 weeks after PVE. Surgery was scheduled for 1 week after a CT or MRI control. The primary study end point was technical success, defined as complete angiographical occlusion of the portal vein. The secondary study end point was evaluation of liver hypertrophy by CT and MRI volumetry and transfer to operability. Results: In all the patients, PVE could be performed with a with a Histoacryl/Lipiodol mixture (n = 20) or a Histoacryl/ Lipiodol mixture with microcoils (n = 1). No procedure-related complications occurred. The volume of the left liver lobe increased significantly (p < 0.0001) by 28% from a mean of 549 ml to 709 ml. Eighteen of twenty-one patients (85.7%) could be transferred to surgery, and the intended resection could be performed as planned in 13/18 (72.3%) patients. Conclusion: Preoperative right-sided PVE using a Histoacryl/Lipiodol mixture is a safe technique and achieves a sufficient hypertrophy of the future liver remnant in the left liver lobe

Depletion of oxygen, nitrate and nitrite in the Peruvian oxygen minimum zone cause an imbalance of benthic nitrogen fluxes

Highlights • Sulphidic event on the shelf resulted in a temporal imbalance of the benthic N cycle. • Bacterial NOx storage is a major source of oxidative power during euxinia. • Peruvian shelf and upper slope sediments are strong recycling sites of fixed N. Abstract Oxygen minimum zones (OMZ) are key regions for fixed nitrogen loss in both the sediments and the water column. During this study, the benthic contribution to N cycling was investigated at ten sites along a depth transect (74–989 m) across the Peruvian OMZ at 12 °S. O2 levels were below detection limit down to ~ 500 m. Benthic fluxes of N2, NO3–, NO2–, NH4+, H2S and O2 were measured using benthic landers. Flux measurements on the shelf were made under extreme geochemical conditions consisting of a lack of O2, NO3– and NO2– in the bottom water and elevated seafloor sulphide release. These particular conditions were associated with a large imbalance in the benthic nitrogen cycle. The sediments on the shelf were densely covered by filamentous sulphur bacteria Thioploca, and were identified as major recycling sites for DIN releasing high amounts of NH4+up to 21.2 mmol m−2 d−1 that were far in excess of NH4+release by ammonification. This difference was attributed to dissimilatory nitrate (or nitrite) reduction to ammonium (DNRA) that was partly being sustained by NO3– stored within the sulphur oxidizing bacteria. Sediments within the core of the OMZ (ca. 200 to 400 m) also displayed an excess flux of N of 3.5 mmol m−2 d−1 mainly as N2. Benthic nitrogen and sulphur cycling in the Peruvian OMZ appears to be particularly susceptible to bottom water fluctuations in O2, NO3−and NO2−, and may accelerate the onset of pelagic euxinia when NO3−and NO2−become depleted

Benthic Dinitrogen Fixation Traversing the Oxygen Minimum Zone Off Mauritania (NW Africa)

Despite its potential to provide new nitrogen (N) to the environment, knowledge on benthic dinitrogen (N2) fixation remains relatively sparse, and its contribution to the marine N budget is regarded as minor. Benthic N2 fixation is often observed in organic-rich sediments coupled to heterotrophic metabolisms, such as sulfate reduction. In the present study, benthic N2 fixation together with sulfate reduction and other heterotrophic metabolisms were investigated at six station between 47 and 1,108 m water depth along the 18°N transect traversing the highly productive upwelling region known as Mauritanian oxygen minimum zone (OMZ). Bottom water oxygen concentrations ranged between 30 and 138 μM. Benthic N2 fixation determined by the acetylene reduction assay was detected at all stations with highest rates (0.15 mmol m−2 d−1) on the shelf (47 and 90 m water depth) and lowest rates (0.08 mmol m−2 d−1) below 412 m water depth. The biogeochemical data suggest that part of the N2 fixation could be linked to sulfate- and iron-reducing bacteria. Molecular analysis of the key functional marker gene for N2 fixation, nifH, confirmed the presence of sulfate- and iron-reducing diazotrophs. High N2 fixation further coincided with bioirrigation activity caused by burrowing macrofauna, both of which showed high rates at the shelf sites and low rates in deeper waters. However, statistical analyses proved that none of these processes and environmental variables were significantly correlated with benthic diazotrophy, which lead to the conclusion that either the key parameter controlling benthic N2 fixation in Mauritanian sediments remains unidentified or that a more complex interaction of control mechanisms exists. N2 fixation rates in Mauritanian sediments were 2.7 times lower than those from the anoxic Peruvian OMZ

Concerted Action of Androgens and Mechanical Strain Shifts Bone Metabolism from High Turnover into an Osteoanabolic Mode

Adhesion of bone cells to the extracellular matrix is a crucial requirement for osteoblastic development and function. Adhesion receptors connect the extracellular matrix with the cyto-skeleton and convey matrix deformation into the cell. We tested the hypothesis that sex hormones modulate mechanoperception of human osteoblastic cells (HOB) by affecting expression of adhesion molecules like fibronectin and the fibronectin receptor. Only dihydrotestosterone (DHT), but not 17β-estradiol, stimulated fibronectin (137%) and fibronectin receptor (252%) protein expression. The effects of deformation strain on HOB metabolism were investigated in a FlexerCell® strain unit. Cyclically applied strain (2.5% elongation) increased DNA synthesis (125%) and interleukin-6 (IL-6) production (170%) without significantly affecting alkaline phosphatase (AP) activity, type I collagen (PICP), or osteoprotegerin (OPG) secretion. 10 nM DHT pretreatment abolished the mitogenic response of HOB to strain and increased AP activity (119%), PICP (163%), and OPG production (204%). In conclusion, mechanical strain stimulates bone remodeling by increasing HOB mitosis and IL-6 production. DHT enhances the osteoanabolic impact of deformation strain by increasing bone formation via increased AP activity and PICP production. At the same time, bone resorption is inhibited by decreased IL-6 and increased OPG secretion into the bone microenvironment