Review: Hydraulic head measurements - New technologies, classic pitfalls

The hydraulic head is one of the most important metrics in hydrogeology as it underlies the interpretation of groundwater flow, the quantification of aquifer properties and the calibration of flow models. Heads are determined based on water-level measurements in wells and piezometers. Despite the importance of hydraulic head data, standard textbooks used in groundwater curricula provide relatively little discussion of the appropriate measurement procedures. This paper presents a review of the literature dealing with the determination of hydraulic heads, and aims to provide quantitative guidance on the likely sources of error and when these can be expected to become important. The most common measurement procedures are discussed and the main sources of error are identified, i.e. those related to (1) the measurement instruments, (2) the conversion from pressure to heads, (3) time lag effects, and (4) observation well defects. It is argued that heads should be determined following welldefined guidelines, and that it should become standard practice in hydrogeology to provide quantitative estimates of the measurement error.Water ManagementCivil Engineering and Geoscience

Brain Activation During Emotional Memory Processing Associated with Subsequent Course of Depression

Major depressive disorder (MDD) is characterized by a heterogeneous course and identifying patients at risk for an unfavorable course is difficult. Neuroimaging studies may identify brain predictors of clinical course and may help to further unravel the neurobiological processes underlying an unfavorable course. We investigated whether brain activation during an emotional memory paradigm is associated with depressive course. To this end, we followed 74 MDD patients and 45 healthy controls (HCs) for 2 years. At baseline, participants performed an emotional word-encoding and -recognition task during functional magnetic resonance imaging. Activation patterns were compared between patients with fast remission (n=22), remission with recurrence (n=23), non-remission (n=29), and HCs. Additionally, linear relations of brain activation and time to remission during the follow-up period were investigated across patients. We observed that during encoding of negative words, non-remitters showed higher activation of the left insula than HCs. Groups also differed in activation of the right hippocampus and left amygdala during negative encoding, with a trend for higher activation in non-remitters compared with HCs. Furthermore, hippocampal activation during negative word encoding was significantly and positively correlated with time to remission, irrespective of illness severity. Our findings suggest that higher activation in the left insula could serve as a neural marker of a naturalistic non-remitting course, whereas higher hippocampal activation is associated with delayed remission. Longitudinal analyses should clarify whether abnormal activation progresses further as a function of time with depression or may serve as load-independent markers of MDD course

The centrosome is an actin-organizing centre.

International audienceMicrotubules and actin filaments are the two main cytoskeleton networks supporting intracellular architecture and cell polarity. The centrosome nucleates and anchors microtubules and is therefore considered to be the main microtubule-organizing centre. However, recurring, yet unexplained, observations have pointed towards a connection between the centrosome and actin filaments. Here we have used isolated centrosomes to demonstrate that the centrosome can directly promote actin-filament assembly. A cloud of centrosome-associated actin filaments could be identified in living cells as well. Actin-filament nucleation at the centrosome was mediated by the nucleation-promoting factor WASH in combination with the Arp2/3 complex. Pericentriolar material 1 (PCM1) seemed to modulate the centrosomal actin network by regulating Arp2/3 complex and WASH recruitment to the centrosome. Hence, our results reveal an additional facet of the centrosome as an intracellular organizer and provide mechanistic insights into how the centrosome can function as an actin-filament-organizing centre