{"id":180337,"date":"2023-04-05T14:57:54","date_gmt":"2023-04-05T18:57:54","guid":{"rendered":"https:\/\/web.uri.edu\/gso\/?page_id=180337"},"modified":"2023-07-14T13:53:41","modified_gmt":"2023-07-14T17:53:41","slug":"the-dhondt-lab-past-research","status":"publish","type":"page","link":"https:\/\/web.uri.edu\/gso\/research\/the-dhondt-lab\/the-dhondt-lab-past-research\/","title":{"rendered":"The D&#8217;Hondt Lab &#8211; Past Research"},"content":{"rendered":"<p><section class=\"cl-wrapper cl-hero-wrapper\"><div class=\"cl-hero   cl-has-accessibility-controls\"><div class=\"cl-hero-proper\"><div class=\"overlay\"><div class=\"block\"><h1>Past Research<\/h1><\/div><\/div><div class=\"still\" style=\"background-image:url(https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt4.jpeg);\"><\/div><div class=\"cl-accessibility-controls-container\"><div class=\"cl-accessibility-controls\"><div class=\"cl-accessibility-icon\" title=\"Accessibility controls\">Accessibility controls<\/div><div class=\"cl-accessibility-control cl-accessibility-motion-control cl-accessibility-control-hidden\"><div class=\"cl-accessibility-control-default\"><div class=\"cl-accessibility-control-button\" title=\"Pause motion\">Pause motion<\/div><div class=\"cl-accessibility-control-label\">Motion: <span class=\"cl-accessibility-syntax\">On<\/span><\/div><\/div><div class=\"cl-accessibility-control-alternate\"><div class=\"cl-accessibility-control-button\" title=\"Play motion\">Play motion<\/div><div class=\"cl-accessibility-control-label\">Motion: <span class=\"cl-accessibility-syntax\">Off<\/span><\/div><\/div><\/div><div class=\"cl-accessibility-control cl-accessibility-contrast-control\"><div class=\"cl-accessibility-control-default\"><div class=\"cl-accessibility-control-button\" title=\"Increase text contrast\">Increase text contrast<\/div><div class=\"cl-accessibility-control-label\">Contrast: <span class=\"cl-accessibility-syntax\">Standard<\/span><\/div><\/div><div class=\"cl-accessibility-control-alternate\"><div class=\"cl-accessibility-control-button\" title=\"Reset text contrast\">Reset text contrast<\/div><div class=\"cl-accessibility-control-label\">Contrast: <span class=\"cl-accessibility-syntax\">High<\/span><\/div><\/div><\/div><div class=\"cl-accessibility-system-setting\"><div class=\"cl-accessibility-toggle\" title=\"Apply my preferences site-wide\"><\/div><div class=\"cl-accessibility-toggle-label\">Apply site-wide<\/div><\/div><\/div><\/div><\/div><\/div><\/section><section class=\"cl-wrapper cl-menu-wrapper\"><nav id=\"\" class=\"cl-menu  \" data-name=\"The Lohmann Lab\" data-show-title=\"0\"><ul id=\"menu-the-dhondt-lab\" class=\"cl-menu-list cl-menu-list-no-js\"><li id=\"menu-item-180358\" class=\"menu-item menu-item-type-post_type menu-item-object-page menu-item-180358\"><a href=\"https:\/\/web.uri.edu\/gso\/research\/the-dhondt-lab\/\">Home<\/a><\/li>\n<li id=\"menu-item-180357\" class=\"menu-item menu-item-type-post_type menu-item-object-page menu-item-180357\"><a href=\"https:\/\/web.uri.edu\/gso\/research\/the-dhondt-lab\/the-dhondt-lab-people\/\">People<\/a><\/li>\n<li id=\"menu-item-180356\" class=\"menu-item menu-item-type-post_type menu-item-object-page menu-item-180356\"><a href=\"https:\/\/web.uri.edu\/gso\/research\/the-dhondt-lab\/the-dhondt-lab-current-research\/\">Research<\/a><\/li>\n<li id=\"menu-item-180354\" class=\"menu-item menu-item-type-post_type menu-item-object-page menu-item-180354\"><a href=\"https:\/\/web.uri.edu\/gso\/research\/the-dhondt-lab\/the-dhondt-lab-expeditions\/\">Expeditions<\/a><\/li>\n<li id=\"menu-item-180352\" class=\"menu-item menu-item-type-post_type menu-item-object-page menu-item-180352\"><a href=\"https:\/\/web.uri.edu\/gso\/research\/the-dhondt-lab\/the-dhondt-lab-technical-developments\/\">Technical Developments<\/a><\/li>\n<li id=\"menu-item-180353\" class=\"menu-item menu-item-type-post_type menu-item-object-page menu-item-180353\"><a href=\"https:\/\/web.uri.edu\/gso\/research\/the-dhondt-lab\/the-dhondt-lab-geobiology-laboratory\/\">Geobiology Laboratory<\/a><\/li>\n<\/ul><\/nav><\/section><\/p>\n<p class=\"paragraph_style\">In the previous millennium, our group\u2019s research focused on a variety of paleobiological and paleoceanographic topics. Specific projects focused on:<span style=\"font-family: Charter, Georgia, serif;font-size: 20px\">the structure and dynamics of ancient ecosystems (including causes and consequences of the end-Cretaceous mass extinction),<\/span><\/p>\n<ul>\n<li>the global distribution of marine zooplankton,<\/li>\n<li>the biological role of alkenones and causes of non-thermal variation in their saturation (a common paleotemperature proxy),<\/li>\n<li>the structure of the ocean-climate system in the \u201cgreenhouse\u201d late Cretaceous (67 million years ago and 83 million years ago),<\/li>\n<li>the evolution of the ocean-climate system in the \u201cicehouse\u201d Pleistocene (0-3 million years ago),<\/li>\n<li>major impact events of the last 65 million years.<\/li>\n<\/ul>\n<h2>Dynamics of ancient ecosystems (including consequences of end-Cretaceous mass extinction)<\/h2>\n<figure id=\"attachment_180339\" aria-describedby=\"caption-attachment-180339\" style=\"width: 300px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-180339\" src=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt-300x224.jpeg\" alt=\"\" width=\"300\" height=\"224\" srcset=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt-300x224.jpeg 300w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt-364x271.jpeg 364w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt.jpeg 404w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-180339\" class=\"wp-caption-text\">Carbon isotopic differences between planktonic and benthic microfossils at an Atlantic site (A) and a Pacific site (B) from 69 to 55 Mya (D\u2019Hondt, 2005). These differences result from the organic carbon flux from surface ocean to deep water. Arrows mark (i) flux reduction at the time of mass extinction (bottom arrow), (ii) initial flux recovery (middle arrow), (iii) final flux recovery (top arrow). Initial planktonic diversification occurred during the first recovery and final diversification closely followed final recovery (Coxall et al., 2006). Other types of data show parallel patterns of collapse and recovery (D\u2019Hondt, 2005).<\/figcaption><\/figure>\n<p class=\"paragraph_style_2\">Members of the D\u2019Hondt laboratory have extensively studied the influence of major biological events (extinctions and radiations) on ecosystem structure and the relevance of metabolic strategies for major evolutionary radiations and survival of major extinctions.<\/p>\n<p class=\"paragraph_style_2\">Our earliest studies in this area principally relied on fossil data. One of these studies showed that open-ocean planktonic foraminiferal populations in the Atlantic, Pacific and Tethyan oceans change completely at the stratigraphic level of the end-Cretaceous impact debris (D\u2019Hondt and Keller, 1991,&nbsp;<span class=\"style_2\">Marine Micropaleontology<\/span>). Another study confirmed that planktonic foraminifera with widely divergent morphologies evolved from a common ancestor very quickly after the end-Cretaceous mass extinction (D\u2019Hondt, 1991,&nbsp;<span class=\"style_2\">Journal of Foraminiferal Research<\/span>).<\/p>\n<p class=\"paragraph_style_2\">We used isotopic and sedimentological data to show that the marine ecosystem and the biogeochemical cycling of carbon did not fully recover from the impact and mass extinction for more than three million years [D\u2019Hondt et al., 1996,&nbsp;<span class=\"style_2\">GSA Special Paper 307<\/span>&nbsp;and 1998,&nbsp;<span class=\"style_2\">Science<\/span>; Adams et al., 2005,&nbsp;<span class=\"style_2\">Paleoceanography<\/span>; D\u2019Hondt, 2005,&nbsp;<span class=\"style_2\">Annual Review of Ecology, Evolution and Systematics&nbsp;<\/span>(<span class=\"style_2\">AREES<\/span>); Coxall et al, 2006,&nbsp;<span class=\"style_2\">Geology<\/span>]. We hypothesized that the long delay in recovery of carbon cycling resulted from altered ecological structure in the post-extinction ocean. Final recovery of planktonic foraminiferal diversity immediately followed final recovery of the carbon cycle (Coxall et al., 2006). This diversification may have resulted from the reappearance of oligotrophic oceans as the organic flux from the surface ocean to deep water fully recovered from the mass extinction. Other studies used Milankovitch-scale sedimentary cycles to show that sedimentation rates declined drastically at the time of impact (Herbert and D\u2019Hondt, 1990,&nbsp;<span class=\"style_2\">EPSL<\/span>) and that the oceanic response to Milankovitch-scale climate forcing was altered for a million years after the impact (D\u2019Hondt et al., 1996,&nbsp;<span class=\"style_2\">Geology<\/span>).<\/p>\n<p class=\"paragraph_style_2\">In other studies, we used stable isotopes of carbon and oxygen to document (1) the occurrence of photosymbiosis among Cretaceous and Paleocene species of planktic foraminifera (D\u2019Hondt and Zachos, 1993,&nbsp;<span class=\"style_2\">Paleoceanography<\/span>; D\u2019Hondt et al., 1994,&nbsp;<span class=\"style_2\">Paleobiology<\/span>; D\u2019Hondt and Zachos, 1998,&nbsp;<span class=\"style_2\">Paleobiology<\/span>) and (2) the role of photosymbiosis in the early Cenozoic radiation of planktonic foraminifera (D\u2019Hondt, 2005; Coxall et al., 2006).<\/p>\n<h2 class=\"paragraph_style_2\"><span class=\"style_2\">Global distribution of marine plankton<\/span><span class=\"style_3\"><br \/>\n<\/span><\/h2>\n<figure id=\"attachment_180340\" aria-describedby=\"caption-attachment-180340\" style=\"width: 300px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-180340 size-medium\" src=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/planktondhondt-300x157.jpeg\" alt=\"\" width=\"300\" height=\"157\" srcset=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/planktondhondt-300x157.jpeg 300w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/planktondhondt-364x191.jpeg 364w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/planktondhondt-500x262.jpeg 500w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/planktondhondt.jpeg 622w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-180340\" class=\"wp-caption-text\">Relationship of planktonic foraminiferal species richness to temperature (Rutherford et al., 1999): (a) actual species richness, (b) species richness vs sea surfate temperature, (c) species richness predicted from b.<\/figcaption><\/figure>\n<p class=\"paragraph_style_2\">We used the Brown University Foraminiferal Data Base and oceanographic data to map the geographic distribution of planktonic foraminiferal species and to quantitatively test hypotheses of the factors that control variation in species richness (Rutherford et al., 1999,&nbsp;<span class=\"style_2\">Nature<\/span>). Our analysis showed that sea surface temperature measured by satellite explains nearly 90 percent of the geographic variation in planktonic foraminiferal diversity throughout the Atlantic Ocean. Temperatures at standard water depths (50, 100, and 150 meters) explain the diversity pattern nearly as well. These findings indicate that geographic variation in zooplankton diversity may be directly controlled by the physical structure of the near-surface ocean. Our results further showed that planktonic foraminiferal diversity does not strictly adhere to the traditional paradigm of continually decreasing diversity from equator to pole. Instead, it peaks in the middle latitudes in all oceans.&nbsp;<\/p>\n<h2 class=\"paragraph_style_2\"><span class=\"style_2\">Biological role of alkenones and their saturation variability in&nbsp;<\/span>Emiliania huxleyi<span class=\"style_3\"><br \/>\n<\/span><\/h2>\n<p class=\"paragraph_style_2\">The ratio of 37-carbon diunsaturated to diunsaturated and triunsaturated alkenones (UK&#8217;37) produced by some haptophytes is widely used as a proxy for past sea surface temperatures.&nbsp; However, our isothermal culturing experiments with&nbsp;<span class=\"style_2\">Emiliania huxleyi<\/span>&nbsp; show that UK&#8217;37 values vary with nutrient availability and cell division rate (Epstein et al., 1998,&nbsp;<span class=\"style_2\">Paleoceanography<\/span>). These results provide a reasonable explanation for large isothermal variation in UK&#8217;37 values of single coccolithophorid strains grown in culture. They also suggest that alkenone-based estimates of past sea surface temperatures may have been influenced by dissolved nutrient concentrations as well as by temperature.<\/p>\n<p class=\"Body\">The biological function of C37 alkenones and, consequently, the cause of their temperature-dependent saturation, was previously unknown. In order to assess their cellular role, we cultured strains of&nbsp;<span class=\"style_2\">E. huxleyi<\/span>&nbsp;at 12:12 and 0:24 light\/dark cycles (Epstein et al., 2001,&nbsp;<span class=\"style_2\">Organic Geochemistry<\/span>). Alkenone concentrations generally increased through both logarithmic and stationary phase in cultures with 12:12 light\/dark cycles. They decreased when&nbsp;<span class=\"style_2\">E. huxleyi<\/span>&nbsp;was energy-deprived (in continuous darkness). These patterns of increasing concentration when light is available and decreasing concentration in darkness are typical of metabolic storage molecules in cultures of other marine phytoplankton. These results suggest that&nbsp;<span class=\"style_2\">Emiliania huxleyi<\/span>&nbsp; uses alkenones for metabolic storage. If C37 alkenones are primarily used for metabolic storage, the temperature dependence of their unsaturation may result from differences in melting point, density, or enzymatic optima of biochemical pathways of the differently saturated alkenones.&nbsp;<\/p>\n<h2 class=\"paragraph_style_4\">Causes of end-Cretaceous mass extinction<\/h2>\n<figure id=\"attachment_180341\" aria-describedby=\"caption-attachment-180341\" style=\"width: 193px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-180341\" src=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt3-193x300.jpeg\" alt=\"\" width=\"193\" height=\"300\" srcset=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt3-193x300.jpeg 193w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt3.jpeg 224w\" sizes=\"auto, (max-width: 193px) 100vw, 193px\" \/><figcaption id=\"caption-attachment-180341\" class=\"wp-caption-text\">Droplets of glass created by the end-Cretaceous impact (Sigurdsson et al., 1991): a) droplet composed of glass and rind altered to clay, b) glass core of another droplet.<\/figcaption><\/figure>\n<p class=\"paragraph_style_2\">Laboratories throughout the world have accumulated a tremendous amount of evidence that the end-Cretaceous extinction was ultimately caused by the impact of a large extraterrestrial object. The first compelling evidence for this extraordinary hypothesis was provided by Alvarez et al. (1980,&nbsp;<span class=\"style_2\">Science<\/span>). Many proximate causes have since been proposed to link the impact to the extinction, including global darkness, acid rain and worldwide wildfire.<\/p>\n<div class=\"paragraph paragraph_style_2\">\n<p>Our research group contributed to this area of study in several ways. We were the first to discover impact glass at the event horizon (Sigurdsson et al., 1991a,&nbsp;<span class=\"style_2\">Nature<\/span>). We linked the composition of that glass to the principal lithologies of the then recently discovered Chicxulub (Mexico) feature (Sigurdsson et al., 1991b,&nbsp;<span class=\"style_2\">Nature<\/span>). Thanks to the work of many laboratories, that feature is now widely recognized as the site of the end-Cretaceous impact. We were among the first to recognize that the unusually sulfur-rich nature of the Chicxulub target may have rendered the impact unusually devastating (Sigurdsson et al., 1992,&nbsp;<span class=\"style_2\">EPSL<\/span>). We then quantified the potential environmental effects of sulfuric and nitric acids generated by the impact and assessed their potential biological consequences (D\u2019Hondt et al., 1994,&nbsp;<span class=\"style_2\">Geology<\/span>).<\/p>\n<\/div>\n<p class=\"paragraph paragraph_style_2\">Schultz and D\u2019Hondt (1996,&nbsp;<span class=\"style_2\">Geology<\/span>) recognized that geophysical signatures of the Chicxulub impact structure closely resemble asymmetries produced by experime<\/p>\n<div id=\"id1\" class=\"style_SkipStroke_3 shape-with-text inline-block\">\n<div class=\"text-content graphic_textbox_layout_style_default_External_213_92\">\n<div class=\"graphic_textbox_layout_style_default\">&nbsp;<\/div>\n<\/div>\n<\/div>\n<p class=\"paragraph paragraph_style_2\">ntal oblique impacts and recognized on planetary surfaces. These signatures suggest that the impact occurred from the southeast at an angle of 20\u201330\u00b0. Consequently, extinction may have been most rapid and severe in the Northern Hemisphere. Geographic variation in floral extinction and recovery is consistent with the proposed trajectory.<\/p>\n<p class=\"Body\">For brief reviews of the evidence for the end-Cretaceous impact, its relation to mass extinction, and proximate causes of extinction, see D\u2019Hondt (1994, in&nbsp;<span class=\"style_2\">Extinction and the Fossil Record<\/span>) and D\u2019Hondt (2005,&nbsp;<span class=\"style_2\">AREES<\/span>).<\/p>\n<h2 class=\"paragraph_style_4\">Structure and evolution of the ocean-climate system<\/h2>\n<figure id=\"attachment_180342\" aria-describedby=\"caption-attachment-180342\" style=\"width: 300px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-180342\" src=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt4-300x143.jpeg\" alt=\"\" width=\"300\" height=\"143\" srcset=\"https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt4-300x143.jpeg 300w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt4-364x173.jpeg 364w, https:\/\/web.uri.edu\/gso\/wp-content\/uploads\/sites\/916\/dhondt4.jpeg 382w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-180342\" class=\"wp-caption-text\">Bandpass filter of a tropical Atlantic oxygen isotope record (Rutherford &amp; D\u2019Hondt, 2000). Note that sustained ~100,000-year glacial cycles began to build about 1.5 Myr ago. Phase-locking of the North Atlantic responses to precessional and semi-precessional cycles began at the same time. We inferred that strengthening of the semi-precessional influence on northern high latitude climate triggered the transition to 100,000-year cycles.<\/figcaption><\/figure>\n<p class=\"paragraph_style_2\">Our studies of the past ocean-climate system principally focused on two topics. The first topic is orbital modulation of the ocean and climate. These studies include the first demonstration of semi-precessional modulation of the ocean-climate system (Park et al., 1993,&nbsp;<span class=\"style_2\">Science<\/span>), the above-mentioned recognition that Milankovitch-scale climate forcing was altered for a million years after the end-Cretaceous impact (D\u2019Hondt et al., 1996,&nbsp;<span class=\"style_2\">Geology<\/span>), and the inference that strengthening of the semi-precessional cycle in the northern hemisphere triggered the transition to sustained 100,000-year glacial cycles 1.5 million years ago (Rutherford and D\u2019Hondt, 2000,&nbsp;<span class=\"style_2\">Nature<\/span>).<\/p>\n<p class=\"Body\">The second topic is the physical structure of the late Cretaceous (~67 Ma) ocean. In these studies, we used oxygen isotopic data to infer that (1) the equator to pole sea-surface temperature gradient was lower than that it is today (D\u2019Hondt and Arthur, 1996,&nbsp;<span class=\"style_2\">Science<\/span>), (2) the tropical sea surface may have been cooler then than it is today and was probably no warmer (D\u2019Hondt and Arthur, 1996,&nbsp;<span class=\"style_2\">Science<\/span>), (3) there were at least three deep watermasses at that time, ranging in temperature between 5-7\u00b0C and 13-15\u00b0C&nbsp;<span class=\"style_5\">(<\/span>D\u2019Hondt and Arthur, 2002,&nbsp;<span class=\"style_2\">Paleoceanography<\/span>), and (4) these watermasses originated principally in the Southern Ocean and the North Atlantic, much like the cooler deep waters of today (D\u2019Hondt and Arthur, 2002,&nbsp;<span class=\"style_2\">Paleoceanography<\/span>). The second of these four results was challenged by Pearson et al. (2001,&nbsp;<span class=\"style_2\">Nature<\/span>), who inferred that the late Maastrichtian tropical sea surface was as warm as that of today or warmer.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the previous millennium, our group\u2019s research focused on a variety of paleobiological and paleoceanographic topics. Specific projects focused on:the structure and dynamics of ancient ecosystems (including causes and consequences of the end-Cretaceous mass extinction), the global distribution of marine zooplankton, the biological role of alkenones and causes of non-thermal variation in their saturation (a [&hellip;]<\/p>\n","protected":false},"author":4762,"featured_media":0,"parent":180328,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":"","_links_to":"","_links_to_target":""},"class_list":["post-180337","page","type-page","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/pages\/180337","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/users\/4762"}],"replies":[{"embeddable":true,"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/comments?post=180337"}],"version-history":[{"count":4,"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/pages\/180337\/revisions"}],"predecessor-version":[{"id":180365,"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/pages\/180337\/revisions\/180365"}],"up":[{"embeddable":true,"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/pages\/180328"}],"wp:attachment":[{"href":"https:\/\/web.uri.edu\/gso\/wp-json\/wp\/v2\/media?parent=180337"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}