Early Formative Period Research Articles

Dynamic changes of nitrogen and phosphorus losses in ephemeral runoff processes by typical storm events in Sichuan Basin, Southwest China

This study was carried out in the Xujiawan watershed in Sichuan Province, China. The area is characterized by easy weathering of bedrock (sedimentary sandstone and shale) and vulnerability to erosion due to coarse soil texture and weak soil structure. The objective of this study was to understand the dynamics of nitrogen (N) and phosphorus (P) losses during typical storm events. The results showed that runoff generation was sudden and ephemeral, giving rise to flash floods with sharp, narrow hydrographs and short time lags in this type of agricultural ecosystems. The time lag effect of runoff formation depended on soil conditions before storm events. Suspended solids (SS) concentration peaks occurred at the beginning of the storm flow and decreased as rainfall progressed. Meanwhile, SS losses increased at the beginning of runoff flow, then decreased due to flow volume change. Concentrations of NO 3 −-N were four times higher than NH 4 +-N in runoff. NO 3 −-N concentrations first decreased as runoff volume increased until reaching relatively low concentrations, then increased again as runoff volume decreased. Both NH 4 +-N and dissolved phosphorus (DP) in runoff remained at low concentrations with a small magnitude of variation. Suspended particulate nitrogen (SN) was the dominant N form. Losses of NO 3 −-N were higher than NH 4 +-N in the dissolved nitrogen (DN). Suspended particulate nitrogen losses were several times higher than DN in the early period of runoff formation, but the ratio of SN/DN decreased gradually as rainfall progressed, and by the end of the storm event the rate was lower than 1, indicating DN took the main form after the early physical flush. In the early period of storm events, suspended particulate phosphorus (SP)/DP was above 70 and decreased as rainfall progressed, but remained higher than 1, which showed that SP was the main form of P loss. The transport of N, and particularly P, was intimately linked to sediment in the runoff, indicating an obvious soil erosion-associated nutrient transport, especially in relation to P loss.

Early Mesoamerican Garbage: Ceramic and Daub Discard Patterns from Cuauhtémoc, Soconusco, Mexico

Formation processes are all too infrequently addressed by archaeologists excavating in Mesoamerica. This paper examines refuse disposal patterns from the site of Cuauhtemoc on the Pacific coast of Chiapas, Mexico, to provide insight into how the site formed and how artifacts accumulated. This analysis uses materials dating between 1600-800 BCE which encompass the centuries before, during and after the late Early Formative or Early Olmec period (i.e., 1250-900 BCE). First, I employ sherds and daub from shared open-air middens and trash-filled pits to explore trash deposit formation through the 800 years that the site was occupied. Next, I use these same classes of data to make synchronic comparisons between five different depositional contexts dating to the Conchas phase (900-800 BCE). For all phases, these analyses demonstrate that pit features received more debris than open- air middens and that material in the latter contexts were more broken up. Further, the low density of daub from late Early Formative period contexts suggests that distinctive architectural customs may have been practised during this time. Conchas phase refuse indicates that waste disposal locations physically separated an elite residential zone from the rest of society and that elite contexts were more intensively used. Accounting for the formation of archaeological deposits allows for more nuanced interpretations of this early Mesoamerican village.

EXPLORING FORMATIVE PERIOD OBSIDIAN BLADE TRADE: THREE DISTRIBUTION MODELS

AbstractObsidian prismatic blades were widely traded across Mesoamerica during the Early and Middle Formative periods. However, it was not until the Late Formative period (400b.c.—a.d. 100) that prismatic blade cores began to be exchanged extensively. Although it is generally accepted that the trading of blades preceded the trading of cores by almost 1,000 years, little is know about the structure of blade trading during the Early and Middle Formative periods. We describe three distributional models for the trade of obsidian prismatic blades: whole-blade trade, processed-blade trade, and local-blade production. These models were evaluated using obsidian consumption data from Oaxaca, the Basin of Mexico, and Tlaxcala. The results indicate that Formative period blade trade involved different forms over time and space.

GEOCHEMICAL ANALYSIS OF VITREOUS ROCKS EXPLOITED DURING THE FORMATIVE PERIOD IN THE ATACAMA REGION, NORTHERN CHILE*

Petrographic analysis and geochemical characterization studies were carried out on vitreous dacite and/or rhyodacite artefacts from Formative period archaeological sites in the upper Salado River Basin in the Atacama Desert, northern Chile. These were compared with samples taken from two source areas located within the subregion, named Linzor and Paniri. Source samples and archaeological specimens were analysed by inductively coupled plasma – mass spectrometry (ICP–MS) combined with optical emission plasma – mass spectrometry (ICP–OES) and atomic absorption spectroscopy (AAS). Results from the limited number of samples analysed indicate that the Linzor source seems to have been the primary source exploited during the Early and Late Formative periods in the Salado River Basin.

A Study of Olmec Serpentinite: exchange, production, distribution, and consumption during the Early and Middle Formative period in Mesoamerica

A Study of Olmec Serpentinite: exchange, production, distribution, and consumption during the Early and Middle Formative period in Mesoamerica

小学校低学年の体育授業における学習集団の形成過程に関する事例研究

The purpose of this case study was to clarify how pupils improve the quality of a learning group, gakushu shudan, while learning the contents of a physical education class, and to examine how a teacher should instruct pupils in order to improve the quality of learning. The gakushu shudan is a concept that aims to promote integral acquisition of subject contents and subsequent character formation in a class.The class study was conducted using short sequences of movement to accompany a story and a song, shudan ohanashi mat for second grade elementary school children. In the shudan ohanashi mat class, two learning activities were conducted. First, pupils discussed the constitution of the short movement sequences. Secondly, pupils synchronized the movement with another member of the group. We then extracted two groups for analysis in detail: one that showed a marked difference in motor skills among the group members and another that showed few differences in motor skills. We then conducted three types of analysis. First, we examined the general content learned by pupils by classification of the learning logs. Secondly, we examined the formative evaluation of the children's group activity through analysis of a “making friends” questionnaire completed by the pupils. Thirdly, we analyzed the utterance of these pupils through “discourse analysis” of characteristic classes.The “discourse analysis” revealed that differences not only in motor skills but also the social background of the pupils affected the formation of the learning group. In a group of 7, D (a girl with low motor skills) began to learn positively with other members of the group when she acquired technical recognition. In a group of 8, a change in the manner of H (a girl with high motor skills) generated good communication between the group members.We conclude that in the early period of formation of a learning group, the following three factors appear to have a positive influence.1) Teacher's guidance in allowing pupils to share means of recognition.2) Teacher's guidance in allowing pupils to interact positively.3) Teacher's approach to group organization by selecting the pupils of democratic nature as leaders.

PaleoVertisols of the northwest Caucasus: (Micro)morphological, physical, chemical, and isotopic constraints on early to late Pleistocene climate

AbstractPhysical and chemical properties, macro‐ and micromorphology, clay mineralogy, and stable‐isotope compositions of paleosols within a pedostratigraphic column (PSC) of early to late Pleistocene age, interstratified paleosols, and loess (NW Caucasus, S Russia) were examined to better understand the evolution of the pedogenic environment over this time period, separating the effects of postpedogenic diagenesis. The column includes eight paleosols and six intercalated loessic horizons. Most of paleosols represent Vertisols or vertic intergrades. Vertic features increase in the middle of the PSC, where the paleosols are more clayey in texture and reddish in color. The morphology of carbonate nodules and soft masses, morphology‐ and depth(age)‐related changes in stable C and O isotope compositions, soil color, redoximorphic features, clay mineralogy, and illuviated clay indicate periods of wetter pedoenvironment in the past and suggest the Pleistocene paleosols are polygenetic and were formed with several wet/dry stages under a climate generally similar to the modern environment in the N Caucasus (mean annual temperature approx. 9°C–12°C). Interpretation of the time sequence of climate/environmental change requires careful separation of pedogenic mineral phases from phases altered by later diagenesis. The early Pleistocene period of paleosol formation appeared to be wetter or more humid, resulting in more significant development of vertic features. The terrestrial ecosystem remained dominated by C3 vegetation throughout the formation of the PSC, with four small periods of change towards a greater proportion of C4 plants or increased moisture stress.

How the Olmec used bitumen in ancient Mesoamerica

Bitumen, found in abundance in Mesoamerica’s southern Gulf Coast region in natural seeps and in many archeological contexts, is an important economic resource and exchange item that has received little consideration in Mesoamerica. Analyses of archeological, ethnoarcheological, and experimental data provide insights on the organization of bitumen processing activities, and the end product (archeological bitumen), which the Olmec (1200–400 BC) used in the production of many items. Archeological data are derived from investigations at El Remolino and Paso los Ortices— two Early Formative period levee sites in the San Lorenzo Olmec region. Our findings suggest that among the Olmec, bitumen processing was organized as a specialized activity, involving multiple production stages, but not necessarily elite involvement or control.

The SCUBA HAlf Degree Extragalactic Survey (SHADES) – VII. Optical/IR photometry and stellar masses of submillimetre galaxies

We present estimates of the photometric redshifts, stellar masses and star formation histories of sources in the Submillimetre Common-User Bolometer Array (SCUBA) HAlf Degree Extragalactic Survey (SHADES). This paper describes the 60 SCUBA sources detected in the Lockman Hole covering an area of ∼320 arcmin 2 . Using photometry spanning the B band to 8 μm, we find that the average SCUBA source forms a significant fraction of its stars in an early period of star formation and that most of the remainder forms in a shorter more intense burst around the redshift it is observed. This trend does not vary significantly with source redshift. However, the sources show a clear increase in stellar mass with redshift, consistent with downsizing. In terms of spectral energy distribution types, only two out of the 51 sources we have obtained photometric redshifts for are best fitted by a quasar-like spectrum, with approximately 80 per cent of the sources being best fitted with late-type spectra (Sc, Im and starburst). By including photometry at 850 μm, we conclude that the average SCUBA source is forming stars at a rate somewhere between 6 and 30 times the rate implied from the rest-frame optical in a dust obscured burst and that this burst creates 15‐65 per cent of the total stellar mass. Using a simplistic calculation, we estimate from the average star formation history that between one in five and one in 15 bright (L∗ + 2 < Loptical < L∗ − 1 mag) galaxies in the field over the interval 0 < z < 3 will at some point in their lifetime

Volcanic impediments in the progressive development of pre-Columbian civilizations in the Ecuadorian Andes

Archaeological investigations in Ecuador have proposed that there appear to be hiatus or anomalous jumps in the progressive development of pre-Columbian indigenous cultures, based upon the fact that their ceramics and tools demonstrate abrupt advances in their sophistication at several horizons in the soil profile. Because some of these horizons are clearly associated with volcanic ash layers, archaeologists have sought a causal relation with volcanism, that is, the eruptive events or their products severely interfered with the early inhabitants, resulting in their abandonment of certain areas. Geological studies of the young volcanoes in the Ecuadorian Andes carried out during the past two decades now allow us to make a more thorough evaluation of the role of volcanism during the Holocene. This contribution briefly describes the principal Holocene volcanic events and the distribution of the corresponding eruptive products found along the InterAndean Valley, from southern Colombia to central Ecuador. Only those events that were sufficiently large that they could have had a detrimental effect on the valley's early residents are discussed. Dacitic and rhyolitic ash flows, as well as numerous debris flows (lahars) have occurred frequently and their deposits cover many valleys and floodplains, where early inhabitants probably settled. The enormous Chillos Valley lahar, associated with the 4500 yBP eruption of Cotopaxi volcano, buried soils containing ceramics of the early Formative Period. However, the greatest impact upon mankind was probably not these short-lived violent events, but rather the burying of settlements and agricultural fields by ash fallout, the effect of which may have lasted hundreds of years. Ash fall layers are observed in pre-Columbian cultural horizons in the soil profile, occurring in the InterAndean Valley, the lower flanks of the Andes, and along Ecuador's Pacific coast, the oldest corresponding to the 5800 yBP eruption of Cotopaxi. This brief study provides the archaeologist with a more detailed listing of notable volcanic events that may guide future investigations of past cultures.

Four-thousand-year-old gold artifacts from the Lake Titicaca basin, southern Peru

Artifacts of cold-hammered native gold have been discovered in a secure and undisturbed Terminal Archaic burial context at Jiskairumoko, a multicomponent Late Archaic-Early Formative period site in the southwestern Lake Titicaca basin, Peru. The burial dates to 3776 to 3690 carbon-14 years before the present (2155 to 1936 calendar years B.C.), making this the earliest worked gold recovered to date not only from the Andes, but from the Americas as well. This discovery lends support to the hypothesis that the earliest metalworking in the Andes was experimentation with native gold. The presence of gold in a society of low-level food producers undergoing social and economic transformations coincident with the onset of sedentary life is an indicator of possible early social inequality and aggrandizing behavior and further shows that hereditary elites and a societal capacity to create significant agricultural surpluses are not requisite for the emergence of metalworking traditions.

People and Space in the Middle Ages, 300-1300 (review)

Reviewed by: People and Space in the Middle Ages, 300-1300 Shane McLeod Davies, Wendy, Guy Halsall, and Andrew Reynolds, eds, People and Space in the Middle Ages, 300-1300 (Studies in the Early Middle Ages, 15), Turnhout, Brepols, 2006; hardback; pp. 366; 50 b/w illustrations, 1 colour plate; R.R.P. €75.00; ISBN 9782503515267. People and Space in the Middle Ages, 300-1300 is another excellent volume in Brepols' 'Studies in the Early Middle Ages' series, combining leading scholarship [End Page 204] with handsome production values. The work is user-friendly, including a number of maps, tables and photos, as well as a useful list of abbreviations. Of particular note is the eleven page glossary at the back of the volume containing key terms. When these terms appear in an article they do so in bold followed by an asterisk, alerting the reader that the term is in the glossary. The volume opens with an introduction by Wendy Davies during which she draws on her own work on plebs in ninth-century Brittany. Andrew Reynolds and Alex Langlands begin proceedings with their thought-provoking article, 'Social Identities on the Macro Scale: A Maximum View of Wansdyke'. The authors argue that Wansdyke was a middle Anglo-Saxon construction that was built amidst border disputes between Wessex and Mercia during an early period of state formation. Birna Lárusdóttir's 'Settlement Organization and Farm Abandonment: The Curious Landscape of Reykjahverfi, North-East Iceland' is a micro-scale study which traces settlement using saga material, chapel sites, pagan graves, cottage ruins, place-names, and an examination of land fertility. Remaining in northern Iceland, Chris Callow employs Guðmundar saga dýra to investigate social connections in twelfth-century Iceland in 'Geography, Communities and Socio-Political Organization in Medieval Northern Ireland'. In 'Communities of Dispersed Settlement: Social Organization at the Ground Level in Tenth-to-Thirteenth-Century Iceland', Orri Vésteinsson disputes the commonly held belief that farmsteads in Iceland were isolated and largely independent, and convincingly argues that a sense of community existed despite the distances involved. The volume returns to England with Steven Bassett's detailed 'Boundaries of Knowledge: Mapping the Land Units of Late Anglo-Saxon and Norman England', revisiting the debate on the commencement of pastoral duties by old minsters. Bassett argues strongly that St Peter's Wootton Wawen (Warwickshire) had a parish before the tenth-century, but as his thesis rests largely on a single charter many are likely to remain unconvinced. Julio Escalona contends that territorial structure in tenth and eleventh-century Castile was more complex than is often thought in 'Mapping Scale Change: Hierarchization and Fission in Castilian Rural Communities During the Tenth and Eleventh Centuries'. 'Central Places and the Territorial Organization of Communities: The Occupation of Hilltop Sites in Early Medieval Northern Castile' by Iñaki Martin Viso presents a more convincing article on Castile with an examination of the continued use of hilltop sites. The relationship between notions of community during the Roman period and its early medieval successor is tackled by Adela Cepas in 'The Ending of the Roman City: The Case of [End Page 205] Clunia in the Northern Plateau of Spain'. The post-Roman evolution of Roman institutions is also the focus of Guy Halsall's tentative work, 'Villas, Territories and Communities in Merovingian Northern Gaul', which employs burial evidence amongst other things to argue that a relationship existed between villa communities and the wider Merovingian world, helping to preserve the villa unit, partly due to its involvement in the taxation system. In 'Community, Identity and the Late Anglo-Saxon Town: The Case of Southern England', Grenville Astill examines the burhs of Wessex for signs of urban identity between the ninth and eleventh centuries, finding that the pattern is inconsistent, and that the pre-burh pattern based on royal centres and minsters may have had more influence than is often thought. A late eleventh-century cartulary provides a rare and detailed glimpse of the dealings of a monastery with local serfs in 'Marmoutier: Familia versus Family: The Relations between Monastery and Serfs in Eleventh-Century North-West France', by Paul Fouracre. The relationship between space, memory, text, and...

Creationism: Religion or Materialism?

Many books have been written by the creationists, or the so-called creation scientists, presenting evidence that is a myth. These people also have Web sites, for example, www.answersingenesis.org, in which they attack established evolutionary concepts and information accepted by the great majority of the scientific community. The web site is mostly a series of highly sarcastic and derogatory rhetorical remarks about scientifically established facts in areas such as genetics, molecular biology, archaeology, paleontology, etc., which present evidence for evolution, with accusations of deliberate fraud and distortion of facts to promote a materialistic philosophy. Why a scientist would want to promote such a philosophy is beyond my comprehension.I have recently read one of the books that attempt to show that is a myth and bad science or deliberate fraud, and I shall use it to illustrate the kinds of tactics these people use to mislead the uninformed and to promote their attempts to include their religious explanations for the origin of life on Earth in school curricula. The book was written by Jonathan Wells, who has Ph.D. degrees in religion and molecular biology. The book is centered around ten of evolution that Wells uses as bases for his attempts to rip apart evolutionary concepts. These icons, according to Wells, are included in most biology text books as evidence for evolution. The book is titled Icons of Evolution, Science or Myth, published by Regnery Publishing, Inc. copyright 2000 by Jonathan Wells. I purchased the book because it might present a different perspective on the subject of evolution. I was astonished to find it a complete distortion of scientific facts accepted by the rational scientific community.The first of Wells's icons is an experiment by graduate student Stanley Miller in the laboratory of Nobel Laureate Harold Urey at the University of Chicago in 1953.1 Professor Urey had theorized that the early Earth atmosphere was a reducing one (as apposed to one containing oxygen) consisting primar- ily of methane (CH4), hydrogen, (H2), nitrogen (N2), ammonia (NH3) and water vapor (H2O). Miller enclosed methane, ammonia and water vapor in a glass apparatus from which he had pumped out all air and through which he ran a current of electricity. He heated the mixture, and after a few days he removed samples and examined them for possible reaction products. He found that after this short time the mixture already contained two amino acids alanine and glycine, which are components of proteins. Similar experiments by others also found amino acids and other biological compounds such as the building blocks of nucleic acids and chlorophyll. In his book, Wells maintains that the primitive atmosphere was devoid of hydrogen, and that oxygen must have been present. The presence of hydrogen is debatable because it could not be held by Earth's gravity, although there certainly must have been some during the early period of Earth's formation, because it is by far the most abundant element in the universe. Wells's evidence that the atmosphere contained oxygen (which would have made the synthesis of biological compounds impossible), is that water molecules are broken down by the action of ultraviolet light to oxygen and hydrogen gases. According to Wells, the hydrogen is lost into space leaving oxygen behind in the Earth's atmosphere. Ammonia also absorbs ultraviolet light, according to Wells, resulting in its destruction.2There are several important facts that Wells chooses to ignore. If water is broken down to hydrogen and oxygen by ultraviolet irradiation, and this is a source of oxygen in the primitive atmosphere, this oxygen would be in the monatomic form (O) which is extremely reactive, especially during the high temperatures of the period, and it would immediately combine with anything available, including hydrogen. Of course, it might also latch on to another monatomic oxygen to form O2. …

"If You Ask Me"

“Cici Anne” was a popular advice column that first appeared in two prominent Turkish journals, Resimli Ay and Resimli Hafta, and subsequently in one of Turkey’s preeminent daily newspapers, Cumhuriyet. The columnist, Sabiha Zekeriya Sertel, was a well-known journalist and outspoken exponent of women’s rights. “Cici Anne,” directed at a more popular audience than Sertel’s other writings, was one outlet for her ideas on women and their circumstances. Each column took as its point of departure a reader’s letter and proceeded to a larger discussion, insisting on women’s need for economic independence, challenging the very concept of namus (honor), and at times calling into question the value of the institution of marriage. The column often appeared in proximity to reports of youth suicides. Thus the column and its context allow us to examine the social tensions produced by the Republican elites’ attempts to redefine family life and gender roles, and to hear, albeit at some remove, the voices of those caught up in such tensions. It also reveals the diversity of voices within the Republican camp in this early formative period.

WHO IS THE “REAL” FATHER OF HPT?

SEVERAL AUTHORS HAVE identified Tom Gilbert as the father of human performance technology. We respectfully disagree—and think he would have too. Gilbert was a brilliant and creative professional who made major contributions to the field, and it seems safe to say that HPT would not have progressed as far as it has without him. But he was not alone. Those of us who have been in the field since the early 1960s can identify a number of other contributors who were significant and even crucial to the early development and expansion of the technology. The early days of HPT were an exciting time. We had a powerful technology that many of us believed could change the world, but it was a new technology and limited in its scope and applications at that stage. Conferences and meetings were characterized by lengthy discussions (sometimes heated, and often extending into the hallways, coffee shops, and bars) about the technology itself, what the field really was, and its potential applications. If we were forced to point to a single initiator of HPT, it would probably be B. F. Skinner, with the publication of The Science of Learning and the Art of Teaching in 1954. But the development of the basic principles that Skinner articulated into a far-reaching technology was the work of many. A number of those people (including Gilbert, Ogden Lindsey, and Dale Brethower) were graduate students under Skinner; others were attracted by the potential power of the principles in Skinner’s writings. Among the candidates for “father” of HPT, in addition to Gilbert, are Lloyd Homme, Jim Evans, Charles Slack, George Geis, Donald Cook, Frances Mechner, Stewart Margolis, Lew Eigen, Bill Deterline, Bob Corrigan, Robert Glaser, Bob Mager, Bob Gagne, Norman Crowder, Bob Morgan, Bob Branson, Walter Dick, Arthur Lumsdain, Dave Klaus, Matt Israel, Jim Holland, Gabriel Ofiesh, and Harvey Block, to mention just a few (including both of us). And they were not all “fathers” either; people like Susan Markle (another Skinner student) were also contributing. In addition several “youngsters” who worked with many of the people listed above also contributed to the growth and development of HPT. These include Brethower, Geary Rummler, Danny Langdon, Joe Harless, Don Bullock, Margo Murray, Stephanie Jackson, and Roger Addison. In this zeitgeist, ideas were pouring in from everywhere. At least a hundred or more names could be added to this list of HPT heroes. It would be impossible to discuss everyone who contributed to the birth of the field, so we have presented just a few of the people we worked with to give a taste of that early formation period. Many people were involved in the early days of instructional systems design, and just as important, many of them were also working to extend the principles of HPT into other areas: juvenile crime reduction; business operations and management; prison rehabilitation; classroom design; mental health; group processes; Job Corps; and a host of other areas, including continual, disappointing forays into the world of education. In the interest of capturing some of the heritage of HPT, each of us has written short sections on the contributions of a few HPT pioneers we worked with. We will dispense with the term “father of . . .” and identify some of the people whom we consider to be an important part of HPT history: a few of our HPT heroes.

Sedentism and food production in early complex societies of the Soconusco, Mexico

This paper presents a case study of the relationship between increasing plant use, sedentism and political complexity among societies on the Pacific coast of southern Mexico during the Early and Middle Formative period (1600–800 bce). I argue that each of these variables increased at different paces in the region. Some of the earliest ceramics in Mesoamerica are documented by 1600 bce as is increasingly sedentary village life. During the following centuries a number of political centres rose and fell. While macrobotanical remains of numerous domestic plant species have been recovered from Early Formative and earlier Archaic period contexts, the overall diet was very broad based with extensive resources exploited from the nearby swamp and estuary systems. Isotopic, ground stone and iconographic data all indicate that the subsistence base underwent a marked transformation during the Middle Formative Conchas phase (900–800 bce) which corresponds to an environmental shift to stable, moist conditions conducive to increased plant production. Therefore, there was over half a millennium during which ceramic-using, horticultural villagers developed political rank prior to the adoption of agriculture and evidence of the first stratified political organization in the region. Evidence from the Soconusco is reviewed and new data are presented from the site of Cuauhtémoc, which was occupied through the entire 800-year period in question.

Evolution and development of Hertwig's epithelial root sheath

Periodontal regeneration and tissue engineering has re-awakened interest in the role of Hertwig's Epithelial Root Sheath (HERS), an epithelial tissue layer first discovered in amphibians more than a century ago. Using developmental, evolutionary, and cell biological approaches, we have, therefore, performed a careful analysis of the role of HERS in root formation and compared our data with clinical findings. Our developmental studies revealed HERS as a transient structure assembled in the early period of root formation and elongation and, subsequently, fenestrated and reduced to epithelial rests of Malassez (ERM). Our comparative evolutionary studies indicated that HERS fenestration was closely associated with the presence of a periodontal ligament and a gomphosis-type attachment apparatus in crocodilians and mammals. Based on these studies, we are proposing that HERS plays an important role in the regulation and maintenance of periodontal ligament space and function. Additional support for this hypothesis was rendered by our meta-analysis of recent clinical reports related to HERS function.

Dopamine profoundly suppresses excitatory transmission in neonatal rat hippocampus via phosphatidylinositol-linked D1-like receptor

Dopamine modulates synaptic transmission in various brain regions. The disorder of dopamine system may be related to neurodevelopmental dysfunction. However, the action of dopamine on synaptic transmission during development is largely unknown. We studied the effect of dopamine on GABAergic and glutamatergic transmission in neonatal rat hippocampus from the early period of synapse formation by whole-cell patch-clamp recordings from CA1 pyramidal cells. Dopamine (100 μM) profoundly decreased the amplitude of GABA A receptor-mediated postsynaptic currents (GABA A-PSCs) to 32.2±5.4% (mean±S.E.M., EC 50: 2.9 μM) in the first postnatal week, when GABA provides excitatory drive. Dopamine also decreased the amplitude of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated excitatory postsynaptic currents (EPSCs) to 29.1±2.7% (EC 50: 18.7 μM) in the second postnatal week, when glutamate responses first appear. The dopamine-induced inhibition declined after these periods and became only partial after postnatal day 30. Further we identified the receptor subtype involved in the dopamine-induced inhibition as phosphatidylinositol-linked D1-like receptor, since 6-chloro-2,3,4,5-tetrahydro-3-methyl-1-(3-methylphenyl)-1H-3-benzazepine-7,8-diol hydrobromide (SKF 83959), a selective agonist for phosphatidylinositol-linked D1-like receptor, clearly mimicked the action of dopamine, and 1-[6-[((17β)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione (U-73122), an inhibitor of phospholipase C, significantly reduced the dopamine-induced inhibition. Dopamine did not change the response to puff-applied GABA or kainic acid, nor the amplitude of miniature GABA A-PSCs or miniature EPSCs. These results suggest that the activation of phosphatidylinositol-linked D1-like receptor profoundly suppresses the excitatory transmission during the early period of synapse formation in the developing hippocampus by presynaptic mechanisms. This study firstly demonstrates the effect of phosphatidylinositol-linked D1-like receptor on synaptic transmission.

Using Refuse Disposal Patterns to Infer Olmec Site Structure in the San Lorenzo Region, Veracruz, Mexico

AbstractIn this paper, I use data gathered from recent excavations conducted in the San Lorenzo region to explore the nature of Olmec site structure. Most studies dealing with this topic have focused on ceremonial precincts at large regional centers. Recent archaeological investigations conducted at the low lying Early Formative period (1500–900 B.C., radiocarbon years) site of El Remolino provide a unique opportunity to study how the Olmec organized domestic space outside primary centers. Although no easily identifiable structural remains were found at El Remolino, refuse disposal patterns are used to infer architectural arrangement and also provide clues on site layout. In order to investigate variations in household spatial structure in the San Lorenzo region, the Remolino data are compared with results from household archaeological studies conducted in an elite precinct (the Group D area) at the regional center of San Lorenzo. Findings indicate that household spatial layout at El Remolino ascribed to a residentially dispersed house-lot type of spatial patterning, whereas spatial structure in the Group D area of San Lorenzo adheres closer to the more nucleated house compound type of spatial patterning.

Wild or Domesticated? Camelids in Early Formative Rock Art of the Atacama Desert (Northern Chile)

AbstractThe absence of suitable methodologies to distinguish between wild and domesticated camelids in rock art has limited the interpretation of visual preferences of Andean prehispanic cultures. Although rock art’s contextual information may provide some indications that help to differentiate between wild and domesticated animals, uncertainty prevails because the relation to camelid forms is indirect. Zoological and zooarchaeological knowledge of South American camelid morphology is used as a means of comparison and identification in Atacama Desert rock art attributed to the Initial Pastoral phase (1500–500 B.C., Early Formative period, northern Chile). Based on this analysis, there are strong arguments for a distinctive graphic representation of wild as opposed to domesticated camelids, as well as a correspondence of these representations to two different modes of subsistence—one of hunters and the other of husbandry-pastoralist societies—which would have coexisted during this transitional period.