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News Article | April 26, 2017
Site: www.eurekalert.org

Innovations in stone knapping technology during the South African Middle Stone Age enabled the creation of early projectile weapons, according to a study published April 26, 2017 in the open-access journal PLOS ONE by Veerle Rots from University of Liège, Belgium, and colleagues. The South African Middle Stone Age (MSA) is considered a period of major technological advancement, with hunter-gatherers introducing new manipulative techniques using heat and pressure to create stone projectile weapons. However, the timing and location of these developments is a topic of much debate. The authors of the present study examined 25 weapon point fragments excavated from the Sibudu Cave site, analyzing their technological and functional differences and comparing them with reference samples produced for the purpose by an experienced knapper. Some of the points had two faces, a likely result of applying pressure to both sides. Some had serrations, or jagged edges, that were likely produced by a technique known as pressure flaking. The researchers found that 14 of the 25 point fragments bore evidence of impact-related damage, animal residues, and wear features that strongly indicated that these points may have been were used for hunting. Examination of the impact-related fractures and the distribution of the points indicated that these points may have been attached to handles to form projectile weapons and that these weapons were projected from a distance, most likely with a flexible spear-thrower or a bow. While further research would help to confirm the timeline and development of stone knapping techniques, the new Sibudu Cave site data may push back the evidence for the use of pressure flaking during the MSA to 77,000 years ago. The authors note that these findings highlight the diversity of technical innovations adopted by southern African MSA humans. In your coverage please use this URL to provide access to the freely available article in PLOS ONE: http://journals. Citation: Rots V, Lentfer C, Schmid VC, Porraz G, Conard NJ (2017) Pressure flaking to serrate bifacial points for the hunt during the MIS5 at Sibudu Cave (South Africa). PLoS ONE 12(4): e0175151. doi:10.1371/journal.pone.0175151 Funding: The functional research at Sibudu Cave is funded by the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013), ERC Grant Agreement Nr. 312283, V. Rots (http://www. ). Veerle Rots is also indebted to the Fund for Scientific Research (FNRS-FRS, CQ2011) (www1.frs-fnrs.be/). The excavation and archaeological research at Sibudu Cave is financed by the Heidelberger Akademie der Wissenschaft (The Role of Culture in Early Expansion of Humans) (http://www. ), the Tübingen Senckenberg Center for Human Evolution and Paleoecology (http://www. ), and the German research Foundation (DFG) grant (CO 226/27-1) (http://www. ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist.


News Article | July 21, 2017
Site: www.eurekalert.org

Bottom Line: In preclinical studies, tumors that consitutively expressed the protein indoleamine 2,3-dioxygenase (IDO1) responded to the cyclooxygenase-2 (COX-2) inhibitor celecoxib (Celebrex) and had improved infiltration of certain subsets of T cells, making them more likely to respond to anti-PD1 therapies. Journal in Which the Study was Published: Cancer Immunology Research, a journal of the American Association for Cancer Research. Author: Benoit J. Van den Eynde, MD, PhD, professor at Ludwig Institute for Cancer Research at de Duve Institute and Université catholique de Louvain in Brussels, Belgium. Background: "A key challenge in cancer immunotherapy is to understand why some patients respond to immunotherapy but many others do not," said Van den Eynde. "If we understand why, we can then select and treat only those patients who will benefit from the treatment, but most importantly, we can devise strategies to make immunotherapy work in those who are not currently responding." Many tumors use IDO1 as a shield to protect themselves from immune attack, explained Van den Eynde. Some of them start building and raising their shields when they are being attacked by T cells, which is called adaptive resistance. In such tumors, IDO1 expression is associated with inflammation and T-cell infiltration. However, some tumors produce IDO1 constitutively (continuously) and have their shields ready and raised before any immune attack. Such tumors are fully protected and can prevent T-cell attack by disabling the T cells right away. "This is what we call intrinsic resistance and may explain why some tumors are 'cold,' meaning, not infiltrated by T cells," Van den Eynde said. "We wanted to understand the molecular mechanisms that make some tumors express IDO1 constitutively," he added. How the Study Was Conducted and Results: Using two human melanoma cell lines, Van den Eynde and colleagues first demonstrated that COX-2 and its product, prostaglandin E2 (PGE2), caused the constitutive expression of IDO1 by utilizing the MAPK, PKC, and PI3K cell-signaling pathways. These results held true in other human tumor cell lines as well, including lung, ovarian, and head and neck cancer cell lines. "These data provide evidence that COX-2 drives tumor-induced immunosuppression through constitutive expression of IDO1," Van den Eynde noted. Next, they showed that immunodeficient mice reconstituted with human lymphocytes and bearing human ovarian tumor xenografts with constitutive IDO1 expression responded to celecoxib as well as the IDO1 inhibitor, epacadostat. "The outcomes we observed with COX-2 inhibitors and IDO1 inhibitors were identical, which came as a surprise," Van den Eynde said. "It is always very useful to have two compounds acting on the same pathway with two different modes of action: In case tumors start resisting one compound, they may still be sensitive to the other." By mining the transcriptomics data of 1,041 different human tumor cell lines from the Broad Institute, the researchers found a correlation between IDO1 expression and activation of the COX-2/PGE2 axis in several cancer types, including stomach, pancreatic, liver, and lung cancers, and sarcoma. Author Comment: "Our studies provide a clear rationale to test, in the clinics, combinations of anti-PD1 immunotherapy and COX-2 inhibitors," Van den Eynde said. "This should be straightforward given the fact that both anti-PD1 and COX-2 inhibitors are already approved for clinical use in different contexts." Initial analysis by the team indicated that about 10 to 50 percent of human tumors express IDO1 constitutively, depending on tumor type. Funding & Disclosures: This study was funded by Ludwig Institute for Cancer Research, Walloon Excellence in Life Sciences and Biotechnology (WELBIO, Belgium), FNRS-Télévie (Belgium), Foundation Against Cancer (Belgium), de Duve Institute and Université catholique de Louvain. Van den Eynde has ownership interest in iTeos Therapeutics, a biotechnology company developing IDO1 inhibitors. To interview Benoit J. Van den Eynde, contact Julia Gunther at julia.gunther@aacr.org or 215-446-6896. About the American Association for Cancer Research Founded in 1907, the American Association for Cancer Research (AACR) is the world's first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 37,000 laboratory, translational, and clinical researchers; population scientists; other health care professionals; and patient advocates residing in 108 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis, and treatment of cancer by annually convening more than 30 conferences and educational workshops, the largest of which is the AACR Annual Meeting with nearly 19,500 attendees. In addition, the AACR publishes eight prestigious, peer-reviewed scientific journals and a magazine for cancer survivors, patients, and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the Scientific Partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration, and scientific oversight of team science and individual investigator grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and other policymakers about the value of cancer research and related biomedical science in saving lives from cancer. For more information about the AACR, visit http://www. .


News Article | July 26, 2017
Site: www.biosciencetechnology.com

In preclinical studies, tumors that consitutively expressed the protein indoleamine 2,3-dioxygenase (IDO1) responded to the cyclooxygenase-2 (COX-2) inhibitor celecoxib (Celebrex) and had improved infiltration of certain subsets of T cells, making them more likely to respond to anti-PD1 therapies, according to data published in Cancer Immunology Research, a journal of the American Association for Cancer Research. “A key challenge in cancer immunotherapy is to understand why some patients respond to immunotherapy but many others do not,” said Benoit J. Van den Eynde, MD, PhD, professor at Ludwig Institute for Cancer Research at de Duve Institute and Université catholique de Louvain in Brussels, Belgium. “If we understand why, we can then select and treat only those patients who will benefit from the treatment, but most importantly, we can devise strategies to make immunotherapy work in those who are not currently responding.” Many tumors use IDO1 as a shield to protect themselves from immune attack, explained Van den Eynde. Some of them start building and raising their shields when they are being attacked by T cells, which is called adaptive resistance. In such tumors, IDO1 expression is associated with inflammation and T-cell infiltration. However, some tumors produce IDO1 constitutively (continuously) and have their shields ready and raised before any immune attack. Such tumors are fully protected and can prevent T-cell attack by disabling the T cells right away. “This is what we call intrinsic resistance and may explain why some tumors are ‘cold,’ meaning, not infiltrated by T cells,” Van den Eynde said. “We wanted to understand the molecular mechanisms that make some tumors express IDO1 constitutively,” he added. Using two human melanoma cell lines, Van den Eynde and colleagues first demonstrated that COX-2 and its product, prostaglandin E2 (PGE2), caused the constitutive expression of IDO1 by utilizing the MAPK, PKC, and PI3K cell-signaling pathways. These results held true in other human tumor cell lines as well, including lung, ovarian, and head and neck cancer cell lines. “These data provide evidence that COX-2 drives tumor-induced immunosuppression through constitutive expression of IDO1,” Van den Eynde noted. Next, they showed that immunodeficient mice reconstituted with human lymphocytes and bearing human ovarian tumor xenografts with constitutive IDO1 expression responded to celecoxib as well as the IDO1 inhibitor, epacadostat. “The outcomes we observed with COX-2 inhibitors and IDO1 inhibitors were identical, which came as a surprise,” Van den Eynde said. “It is always very useful to have two compounds acting on the same pathway with two different modes of action: In case tumors start resisting one compound, they may still be sensitive to the other.” By mining the transcriptomics data of 1,041 different human tumor cell lines from the Broad Institute, the researchers found a correlation between IDO1 expression and activation of the COX-2/PGE2 axis in several cancer types, including stomach, pancreatic, liver, and lung cancers, and sarcoma. “Our studies provide a clear rationale to test, in the clinics, combinations of anti-PD1 immunotherapy and COX-2 inhibitors,” Van den Eynde said. “This should be straightforward given the fact that both anti-PD1 and COX-2 inhibitors are already approved for clinical use in different contexts.” Initial analysis by the team indicated that about 10 to 50 percent of human tumors express IDO1 constitutively, depending on tumor type. This study was funded by Ludwig Institute for Cancer Research, Walloon Excellence in Life Sciences and Biotechnology (WELBIO, Belgium), FNRS-Télévie (Belgium), Foundation Against Cancer (Belgium), de Duve Institute and Université catholique de Louvain. Van den Eynde has ownership interest in iTeos Therapeutics, a biotechnology company developing IDO1 inhibitors.


News Article | December 7, 2016
Site: www.eurekalert.org

The highly mobile motion of an ice disk compares to the Leidenfrost effect that drives the motion of rapidly boiling water droplets WASHINGTON, D.C., December 7, 2016 -- Resembling the Leidenfrost effect seen in rapidly boiling water droplets, a disk of ice becomes highly mobile due to a levitating layer of water between it and the smooth surface on which it rests and melts. The otherwise random rotation and translation (sliding) of the ice block can be directed by controlling the flow dynamics of the melted ice-turned-water close to the disk surface. While attempting to prepare an experiment to study the adhesion properties of ice, Stéphane Dorbolo, a FNRS senior researcher in physics hosted by the Université de Liège in Belgium, dropped a petri dish-shaped block of ice onto the smooth, concrete floor. Its unusual motion, acquiring seemingly random rotation as it moved across the floor, prompted Dorbolo to investigate further, where his eventual results about ice levitation are published in this week's journal Physics of Fluids, by AIP publishing. "The story was completely different because of this accident," said Dorbolo. "The question was, why does it move? Because actually, it's very common procedure: you have an ice block and then it melts. But it doesn't happen, for example, on a plastic plate. It only happens on very flat stone, or on a metal plate. That was the start." The contact area is much smaller on a skating rink, between a skate blade edge and ice , but it's for the same reason that ice-skate blade edges must be smooth and typically metallic, in hockey and figure skating, where smooth motion is pivotal. The key area of interest in this investigation was the melting interface, where the surface supporting an ice disk - be it smooth and non-porous stone, metal or even a pool of water - supplies relative heat and rapidly melts the ice. Dorbolo and his team previously studied the dynamics of such an ice disk melting while resting on the liquid surface of water. These motions of the ice are governed by different interactions than if the ice rested on a solid surface, but the investigations proved as a simpler, initial step and gave insight into the dynamics of how the newly melted water flows from the ice. "The main idea was to study the ice disk melting on a plate, but we started by studying the ice disk on a bath," said Dorbolo. "Actually, when we came back to the melting of the ice disk on a plate we discovered a completely different mechanism." The effect resembles the Leidenfrost effect, the focus of numerous YouTube videos featuring water droplets "walking" and "dancing" as they float over smooth surfaces hot enough to rapidly boil the underside of the droplets. The rapid boiling produces a levitating cushion of vapor (steam) between the droplet and heating surface, increasing the droplet mobility. "It means you must have a thermal reservoir, like the stone or metallic plate, to melt the ice fast enough," Dorbolo said. "So the melting flow rate is important. If it's not sufficient, you don't have this lubricating film between the disk and the plate and it cannot move. That's why we said that it was similar the Leidenfrost effect." Dorbolo carefully pointed out that the levitating liquid cushion of their ice disks was not exactly analogous to the floating effect felt by the Leidenfrost droplets, though their interest in controlling the motion was one held common to many droplet experiments. The solid-liquid-solid configuration of this phenomena, as opposed to that of solid-gas-liquid in the case of the droplets, led the team to focus on water outflow from the continuously melting ice to investigate control of the disk motion. "You have a disk and it must melt fast enough to have this lubrication film between the disk and the plate, and then because of this lubrication, the ice disk is very mobile. So if you don't control the melting, you will see the ice block move," Dorbolo said If you do control the melting, or more specifically the flow of the melted ice near the disk, the team showed that the final spinning and sliding motion of the ice disks could be sustained and directed. This control was achieved, essentially, in the form of a small hole Dorbolo's team made in the surface of the metal plate, near the floating ice. The hole lead to an exit pipe, acting as a reservoir through which the water continuously escaped after melting on the thermalized metal. To further contain the water flow, the team also used careful placement of petroleum jelly on the plate. They tracked the motion of a given petri dish-formed ice-disk using a black ellipse frozen on top the ice, imaged by a camera during the experiment. The contrast and asymmetrical shape allowed for precise monitoring of both linear and rotational motion of the disks which Dorbolo's group then analyzed in relation to other data, such as temperature and flow rates. Their findings offer insight into the precise mechanisms of the motion and what factors drive motions - such as the thickness of the water layer or the direction of the circular flow around the disk edge. The scientists also highlight how the liquid effects compare to the analogous vapor effects on droplets in the more widely studied Leidenfrost effect. Although the project diverges from Dorbolo's primary research goal, he acknowledges many possible ways the study could be further pursued, whether by changing the shape of the ice or the plate surface structure to effect flow dynamics. He also confidently said, "People will have ideas." Physics of Fluids is devoted to the publication of original theoretical, computational, and experimental contributions to the dynamics of gases, liquids, and complex or multiphase fluids.


News Article | December 5, 2016
Site: www.eurekalert.org

Combination drug treatments have become successful at long-term control of HIV infection, but the goal of totally wiping out the virus and curing patients has so far been stymied by HIV's ability to hide out in cells and become dormant for long periods of time. Now a new study on HIV's close cousin, simian immunodeficiency virus (SIV), in macaques finds that a proposed curative strategy could backfire and make things worse if the virus is in fact lurking in the brain. One of the proposed curative strategies for HIV, known as "shock and kill," first uses so-called latency-reversing agents to wake up dormant viruses in the body, making them vulnerable to the patient's immune system. The idea is that this, in combination with antiretroviral medicines, would wipe out the majority of infected cells. But based on a study of macaques with SIV, a group of researchers warns in a report published in the January 2 issue of the journal AIDS that such a strategy could cause potentially harmful brain inflammation. "The potential for the brain to harbor significant HIV reservoirs that could pose a danger if activated hasn't received much attention in the HIV eradication field," says Janice Clements, Ph.D., professor of molecular and comparative pathobiology at the Johns Hopkins University School of Medicine. "Our study sounds a major cautionary note about the potential for unintended consequences of the shock-and-kill treatment strategy." HIV research efforts have long focused on prevention and developing antiretroviral therapies that keep the virus in check without eradicating it, essentially transforming HIV into a manageable chronic condition, says Lucio Gama, Ph.D., assistant professor of molecular and comparative pathobiology at Johns Hopkins and the lead author of the new study. Then, in 2009, a group in Berlin reported it had cured a man of HIV by giving him a bone marrow transplant from a donor whose genetics conferred natural resistance to the virus. This galvanized federal funding of new research projects aimed at finding a more broadly applicable "AIDS cure," Gama says. He and Clements are part of that pursuit as members of the Collaboratory of AIDS Researchers for Eradication. One cure strategy being pursued is to find a medication that would "wake up" virus in the reservoirs, forcing it to reveal itself. But Gama says that could be problematic if HIV reservoirs exist in the brain, and investigators already had some evidence that they do: the many cases of AIDS dementia that developed before the current antiretroviral cocktail treatment was developed. "Research had also shown that HIV can infect monocytes in the blood, which we know cross into the brain," he says. But no studies had definitively answered whether significant reservoirs of latent HIV in patients under long-term therapy could be sustained in the brain -- in part because, in autopsies, it is unclear whether virus detected in the brain comes from brain cells themselves or surrounding blood. For the new study, Clements, Gama and their collaborators treated three pig-tailed macaque monkeys infected with SIV with antiretrovirals for more than a year. Then the researchers gave two of the macaques ingenol-B, a latency-reversing agents thought to "wake up" the virus. "We didn't really see any significant effect," Gama says, "So we coupled ingenol-B with another latency-reversing agent, vorinostat, which is used in some cancer treatments to make cancer cells more vulnerable to the immune system." The macaques also continued their course of antiretrovirals throughout the experiment. After a 10-day course of the combined treatment, one of the macaques remained healthy, while the other developed symptoms of encephalitis, or brain inflammation, Gama says, and blood tests revealed an active SIV infection. When the animal's illness worsened, the researchers humanely killed it and carefully removed the blood from its body so that blood sources of the virus would not muddle their examination of the brain. Testing revealed SIV was still present in the brain, but only in one of the regions analyzed: the occipital cortex, which processes visual information. The affected area was so small that "we almost missed it," he says. Gama cautions that the results of their study on macaques with SIV may not apply to humans with HIV. It's also possible, he says, that the encephalitis was transient and could have resolved by itself. Still, he says, the results signal a need for extra caution in exploring ways to flush out HIV reservoirs and eradicate the virus from the body. Other authors on the paper are Celina M. Abreu, Erin N. Shirk, Sarah L. Price, Ming Li, Greg M. Laird, Kelly A. Metcalf Pate and Robert F. Siliciano of The Johns Hopkins University; Stephen W. Wietgrefe and Ashley T. Haase of the University of Minnesota; Shelby L. O'Connor of the University of Wisconsin; Luiz Pianowski of Kyolab in Brazil; Carine van Lint of the Université Libre de Bruxelles in Belgium; and the LRA-SIV Study Group. Research reported in this publication was supported by the National Institute of Mental Health (grant number P01MH070306-01), the National Institute of Allergy and Infectious Disease (grant number U19A1076113), the National Institutes of Health's Office of the Director (grant numbers P40OD013117 and P51OD011106), the Research Facilities Improvement Program (grant numbers RR15459-01 and RR020141-01), the France Recherche Nord & Sud Sida-HIV Hépatites, the Belgian Fund for Scientific Research (FRS-FNRS Belgium), the Fondation Roi Baudouin, the NEAT program and the Wallo on Region (the Excellence Program Cibles).


News Article | December 7, 2016
Site: phys.org

While attempting to prepare an experiment to study the adhesion properties of ice, Stéphane Dorbolo, a FNRS senior researcher in physics hosted by the Université de Liège in Belgium, dropped a petri dish-shaped block of ice onto the smooth, concrete floor. Its unusual motion, acquiring seemingly random rotation as it moved across the floor, prompted Dorbolo to investigate further, where his eventual results about ice levitation are published in this week's journal Physics of Fluids, by AIP publishing. "The story was completely different because of this accident," said Dorbolo. "The question was, why does it move? Because actually, it's very common procedure: you have an ice block and then it melts. But it doesn't happen, for example, on a plastic plate. It only happens on very flat stone, or on a metal plate. That was the start." The contact area is much smaller on a skating rink, between a skate blade edge and ice , but it's for the same reason that ice-skate blade edges must be smooth and typically metallic, in hockey and figure skating, where smooth motion is pivotal. The key area of interest in this investigation was the melting interface, where the surface supporting an ice disk – be it smooth and non-porous stone, metal or even a pool of water – supplies relative heat and rapidly melts the ice. Dorbolo and his team previously studied the dynamics of such an ice disk melting while resting on the liquid surface of water. These motions of the ice are governed by different interactions than if the ice rested on a solid surface, but the investigations proved as a simpler, initial step and gave insight into the dynamics of how the newly melted water flows from the ice. "The main idea was to study the ice disk melting on a plate, but we started by studying the ice disk on a bath," said Dorbolo. "Actually, when we came back to the melting of the ice disk on a plate we discovered a completely different mechanism." The effect resembles the Leidenfrost effect, the focus of numerous YouTube videos featuring water droplets "walking" and "dancing" as they float over smooth surfaces hot enough to rapidly boil the underside of the droplets. The rapid boiling produces a levitating cushion of vapor (steam) between the droplet and heating surface, increasing the droplet mobility. "It means you must have a thermal reservoir, like the stone or metallic plate, to melt the ice fast enough," Dorbolo said. "So the melting flow rate is important. If it's not sufficient, you don't have this lubricating film between the disk and the plate and it cannot move. That's why we said that it was similar the Leidenfrost effect." Dorbolo carefully pointed out that the levitating liquid cushion of their ice disks was not exactly analogous to the floating effect felt by the Leidenfrost droplets, though their interest in controlling the motion was one held common to many droplet experiments. The solid-liquid-solid configuration of this phenomena, as opposed to that of solid-gas-liquid in the case of the droplets, led the team to focus on water outflow from the continuously melting ice to investigate control of the disk motion. "You have a disk and it must melt fast enough to have this lubrication film between the disk and the plate, and then because of this lubrication, the ice disk is very mobile. So if you don't control the melting, you will see the ice block move," Dorbolo said If you do control the melting, or more specifically the flow of the melted ice near the disk, the team showed that the final spinning and sliding motion of the ice disks could be sustained and directed. This control was achieved, essentially, in the form of a small hole Dorbolo's team made in the surface of the metal plate, near the floating ice. The hole lead to an exit pipe, acting as a reservoir through which the water continuously escaped after melting on the thermalized metal. To further contain the water flow, the team also used careful placement of petroleum jelly on the plate. They tracked the motion of a given petri dish-formed ice-disk using a black ellipse frozen on top the ice, imaged by a camera during the experiment. The contrast and asymmetrical shape allowed for precise monitoring of both linear and rotational motion of the disks which Dorbolo's group then analyzed in relation to other data, such as temperature and flow rates. Their findings offer insight into the precise mechanisms of the motion and what factors drive motions – such as the thickness of the water layer or the direction of the circular flow around the disk edge. The scientists also highlight how the liquid effects compare to the analogous vapor effects on droplets in the more widely studied Leidenfrost effect. Although the project diverges from Dorbolo's primary research goal, he acknowledges many possible ways the study could be further pursued, whether by changing the shape of the ice or the plate surface structure to effect flow dynamics. He also confidently said, "People will have ideas." Explore further: Combining nanotextured surfaces with the Leidenfrost effect for extreme water repellency More information: S. Dorbolo et al. Spontaneous rotation of an ice disk while melting on a solid plate, Physics of Fluids (2016). DOI: 10.1063/1.4967399


Grimaldi G.,FNRS | Manto M.,FNRS
Sensors | Year: 2010

Neurological tremor is the most common movement disorder, affecting more than 4% of elderly people. Tremor is a non linear and non stationary phenomenon, which is increasingly recognized. The issue of selection of sensors is central in the characterization of tremor. This paper reviews the state-of-the-art instrumentation and methods of signal processing for tremor occurring in humans. We describe the advantages and disadvantages of the most commonly used sensors, as well as the emerging wearable sensors being developed to assess tremor instantaneously. We discuss the current limitations and the future applications such as the integration of tremor sensors in BCIs (brain-computer interfaces) and the need for sensor fusion approaches for wearable solutions. © 2010 by the authors.


Manto M.U.,FNRS | Jissendi P.,Service de Neuroradiologie
Frontiers in Neuroanatomy | Year: 2012

The study of the links and interactions between development and motor learning has noticeable implications for the understanding and management of neurodevelopmental disorders. This is particularly relevant for the cerebellum which is critical for sensorimotor learning. The olivocerebellar pathway is a key pathway contributing to learning of motor skills. Its developmental maturation and remodeling are being unraveled. Advances in genetics have led to major improvements in our appraisal of the genes involved in cerebellar development, especially studies in mutant mice. Cerebellar neurogenesis is compartmentalized in relationship with neurotransmitter fate. The Engrailed-2 gene is a major actor of the specification of cerebellar cell types and late embryogenic morphogenesis. Math1, expressed by the rhombic lip, is required for the genesis of glutamatergic neurons. Mutants deficient for the transcription factor Ptf1a display a lack of Purkinje cells and gabaergic interneurons. Rora gene contributes to the developmental signaling between granule cells and Purkinje neurons. The expression profile of sonic hedgehog in postnatal stages determines the final size/shape of the cerebellum. Genes affecting the development impact upon the physiological properties of the cerebellar circuits. For instance, receptors are developmentally regulated and their action interferes directly with developmental processes. Another field of research which is expanding relates to very preterm neonates. They are at risk for cerebellar lesions, which may themselves impair the developmental events. Very preterm neonates often show sensori-motor deficits, highlighting another major link between impaired developments and learning deficiencies. Pathways playing a critical role in cerebellar development are likely to become therapeutical targets for several neurodevelopmental disorders.


News Article | December 7, 2016
Site: www.rdmag.com

Resembling the Leidenfrost effect seen in rapidly boiling water droplets, a disk of ice becomes highly mobile due to a levitating layer of water between it and the smooth surface on which it rests and melts. The otherwise random rotation and translation (sliding) of the ice block can be directed by controlling the flow dynamics of the melted ice-turned-water close to the disk surface. While attempting to prepare an experiment to study the adhesion properties of ice, Stéphane Dorbolo, a FNRS senior researcher in physics hosted by the Université de Liège in Belgium, dropped a petri dish-shaped block of ice onto the smooth, concrete floor. Its unusual motion, acquiring seemingly random rotation as it moved across the floor, prompted Dorbolo to investigate further, where his eventual results about ice levitation are published in this week's journal Physics of Fluids, by AIP publishing. "The story was completely different because of this accident," said Dorbolo. "The question was, why does it move? Because actually, it's very common procedure: you have an ice block and then it melts. But it doesn't happen, for example, on a plastic plate. It only happens on very flat stone, or on a metal plate. That was the start." The contact area is much smaller on a skating rink, between a skate blade edge and ice , but it's for the same reason that ice-skate blade edges must be smooth and typically metallic, in hockey and figure skating, where smooth motion is pivotal. The key area of interest in this investigation was the melting interface, where the surface supporting an ice disk – be it smooth and non-porous stone, metal or even a pool of water – supplies relative heat and rapidly melts the ice. Dorbolo and his team previously studied the dynamics of such an ice disk melting while resting on the liquid surface of water. These motions of the ice are governed by different interactions than if the ice rested on a solid surface, but the investigations proved as a simpler, initial step and gave insight into the dynamics of how the newly melted water flows from the ice. "The main idea was to study the ice disk melting on a plate, but we started by studying the ice disk on a bath," said Dorbolo. "Actually, when we came back to the melting of the ice disk on a plate we discovered a completely different mechanism." The effect resembles the Leidenfrost effect, the focus of numerous YouTube videos featuring water droplets"walking" and "dancing" as they float over smooth surfaces hot enough to rapidly boil the underside of the droplets. The rapid boiling produces a levitating cushion of vapor (steam) between the droplet and heating surface, increasing the droplet mobility. "It means you must have a thermal reservoir, like the stone or metallic plate, to melt the ice fast enough," Dorbolo said. "So the melting flow rate is important. If it's not sufficient, you don't have this lubricating film between the disk and the plate and it cannot move. That's why we said that it was similar the Leidenfrost effect." Dorbolo carefully pointed out that the levitating liquid cushion of their ice disks was not exactly analogous to the floating effect felt by the Leidenfrost droplets, though their interest in controlling the motion was one held common to many droplet experiments. The solid-liquid-solid configuration of this phenomena, as opposed to that of solid-gas-liquid in the case of the droplets, led the team to focus on water outflow from the continuously melting ice to investigate control of the disk motion. "You have a disk and it must melt fast enough to have this lubrication film between the disk and the plate, and then because of this lubrication, the ice disk is very mobile. So if you don't control the melting, you will see the ice block move," Dorbolo said If you do control the melting, or more specifically the flow of the melted ice near the disk, the team showed that the final spinning and sliding motion of the ice disks could be sustained and directed. This control was achieved, essentially, in the form of a small hole Dorbolo's team made in the surface of the metal plate, near the floating ice. The hole lead to an exit pipe, acting as a reservoir through which the water continuously escaped after melting on the thermalized metal. To further contain the water flow, the team also used careful placement of petroleum jelly on the plate. They tracked the motion of a given petri dish-formed ice-disk using a black ellipse frozen on top the ice, imaged by a camera during the experiment. The contrast and asymmetrical shape allowed for precise monitoring of both linear and rotational motion of the disks which Dorbolo's group then analyzed in relation to other data, such as temperature and flow rates. Their findings offer insight into the precise mechanisms of the motion and what factors drive motions – such as the thickness of the water layer or the direction of the circular flow around the disk edge. The scientists also highlight how the liquid effects compare to the analogous vapor effects on droplets in the more widely studied Leidenfrost effect. Although the project diverges from Dorbolo's primary research goal, he acknowledges many possible ways the study could be further pursued, whether by changing the shape of the ice or the plate surface structure to effect flow dynamics. He also confidently said, "People will have ideas."


News Article | December 21, 2016
Site: phys.org

For the first time, geologists from the University of Liège have been able to determine the nature of the minerals present on the surface of Mercury - one of the four telluric planets in our solar system. Their study, published this week in the journal Nature Geoscience, is based on experiments conducted in laboratory at extreme temperatures, to reconstitute the conditions observed during the crystallization of magmas. The mineralogy of rocks on the surface of the planets is an excellent indicator of the origin and evolution of the planets since the origins of the solar system. Between 2011 and 2015, the Messenger probe sent by NASA orbited Mercury and collected tens of thousands physico-chemical measurements of the Mercury crust. It is on the basis of these measurements that Olivier Namur and Bernard Charlier, researchers at FRS-FNRS, were able to reproduce - in their new experimental petrology laboratory at Université de Liège using a unique equipment in Belgium - samples of Mercury magma. Their conclusions help us to better understand the mineralogy of Mercury, which remained an enigma, and more globally the evolution of this planet. The crust of Mercury is of magmatic origin, produced by lava from the mantle between 4.2 and 3.5 billion years ago. In their study, the two researchers were able to define different regions in the northern hemisphere of Mercury, each characterized by a specific mineralogy. Their major discovery is the link between the age of these regions and the mineralogy of the lava on their surface, which demonstrates the major role of the thermal evolution of Mercury on its volcanic history. The magmatic activity on Mercury was interrupted early 3.5 billion years ago, making it the telluric planet that cooled the most rapidly in our solar system. Explore further: Researchers find most volcanic activity on Mercury stopped about 3.5 billion years ago More information: Olivier Namur et al. Silicate mineralogy at the surface of Mercury, Nature Geoscience (2016). DOI: 10.1038/ngeo2860

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