The viola d’amore is a small bowed instrument that was in use predominantly from the second half of the seventeenth century to the end of the eighteenth. Initially, the name viola d’amore referred to a treble viol strung with wire strings, but it underwent a transformation c.1700 with the addition of sympathetic strings, with the bowed strings changing from wire to gut. The history of the viola d’amore centres on German-speaking regions of Europe, with the cultivation of the sympathetic strings stemming from Austria. While originally reserved for the wealthiest classes, evidence suggests that the viola d’amore became a widely used instrument due to the number of extant instruments in collections today. Due to the viola d’amore existing in two forms, the historical and organological context of the instrument is of paramount importance. Thus, this thesis addresses not only the viola d’amore in both its forms, but also its predecessors, the baryton and the englische violet, charting their development and ultimate influence on the invention of the viola d’amore with sympathetic strings. The suggested line of evolution is supported by measurements and observations of construction of the individual instruments, as well as physical examinations of extant specimens, and is considered in light of relevant iconography, music scores, newspaper advertisements and literary references. The research has led to the redrawing of parameters for each instrument, clearly defining the instruments’ functions and notable attributes. This thesis is the first complete organological study of the viola d’amore and other bowed instruments with additional wire strings. It presents a comprehensive review of the associated literature for each instrument concerned, as well as measurements and organological observations, with particular emphasis on design and construction. Additionally, it also considers the development of wire-strung instruments in England, briefly including: native music wire-drawing; the existence of other instruments with the name ‘d’amore’ and its variations; and lesser considered instruments with sympathetic strings such as the hardanger fiddle and trumpet marine. Finally, the conclusion is drawn that the viola d’amore with sympathetic strings may be considered as the epitome of Baroque instrumental design.

Darbo objektas yra lietuvių pasakojamoji tautosakos kūriniai, kuriuose figūruoja medis. Problema - kokie medžiai ir kaip yra vaizduojami lietuvių pasakojamojoje tautosakoje. Tikslas – išsiaiškinti, su kokiais personažais yra susiję įvairūs pasakojamojoje tautosakoje vaizduojami medžiai bei parodyti senųjų tikėjimų bei papročių įtak�� šių medžių traktuotei. Tikslui pasiekti išsikelti tokie uždaviniai: 1. Aptarti medžių santykį su mitinėmis esybėmis. 2. Atskleisti medžių ryšį su mirusiaisiais bei laidotuvių apeigomis. 3. Pateikti stebuklingų medžių traktuotę. 4. Aptarti kelmo vaidmenį. 5. Išryškinti medžių funkcijas. Rašant darbą naudotasi kompleksine metodologija. Tokį pasirinkimą lėmė įvairus analizuojamosios medžiagos pobūdis. Daugiausia naudotasi lyginamuoju ir interpretaciniu bei aprašomuoju metodais. Be įvado ir išvadų, darbą sudaro keturios pagrindinės dalys: Medžiai ir mitinės esybės lietuvių pasakojamojoje tautosakoje; Medžiai ir mirusieji lietuvių pasakojamojoje tautosakoje; Stebuklingi medžiai lietuvių pasakojamojoje tautosakoje; Medžio kelams lietuvių pasakojamojoje tautosakoje. Pirmojoje darbo dalyje išskiriami ir aptariami tam tikros rūšies medžių santykiai su konkrečiomis vyriškosios bei moteriškosios prigimties mitinėmis esybėmis. Nurodoma, jog medžiai gali atlikti mediatoriaus funkciją, dažnai mitinės būtybės juose lokalizuojamos. Medžio dalimis gali virsti mitinių esybių dovanoti objektai. Taip pat pažymima, kokie medžiai mitinėms būtybės kelia grėsmę... [toliau žr. visą tekstą] / The work aims at analyzing Lithuanian verbal folklore in which the picture of trees is presented. To reveal the role of trees in Lithuanian verbal folklore by distinguishing the most characteristic features of expression. The purpose is achieved by analyzing the aspects of Lithuanian verbal folklore which reveal the cult of secret trees in the most evident way. The substantial aspects of the work are as follows: 1. The Detachment of Main relationships Formation by myths and trees; 2. the Revelation of the Motives of the exequies and their relationship with trees 3. Show the approach of the trees; 4. Show the role of the stump; 5. To develop the trees functions. The work compound with four main parts: Trees and myths in Lithuanian verbal folklore; Tress and death in Lithuanian verbal folklore; Wonder tress in Lithuanian verbal folklore; Tree’s stump in Lithuanian verbal folklore. In the first part of the work, represents the main sorts of the trees and their relationships with myths. It is seen that trees can help people contact with goods. Usually the tree is the living place of myths. Objects, witch man gets from myths can become the parts of the tree. It is also seen which kinds of trees helps mans to protect them self’s from evil. In the second part of the work, main attention is focused in the relationship of trees and death. In the Lithuanian verbal folklore is text which proves, that after death mans soul finds in the trees. It is shown the sorts of this tree... [to full text]

In a fascinating article in The Journal of Ethics, Eleonore Stump contends that while the flicker of freedom defense is the best available strategy for defending the principle of alternative possibilities against the threat posed to that principle by the Frankfurt cases, the defense is ultimately unsuccessful. In this article I identify a number of difficulties with Stump’s criticism of the flicker strategy. Along the way, I also clarify various nuances of the strategy that often get overlooked, and I highlight the advantages of one version of it in particular.

No description available.

Forest biomass burned for energy purposes does not need to be accounted for under IPCC rules. This has led to a number of countries considering tree stump harvesting as a source of forest biomass. However there are concerns that the soil disturbance that this may entail could have adverse environmental effects, including the loss of sequestered carbon from the soil. Published results differ in the degree and nature of stump harvesting soil disturbance. Two widely used measures employed in stump harvesting soil disturbance studies are visual assessment of disturbance extent and bulk density measures of the nature of disturbance. Each of these has limitations. This study seeks to extend the insight into both the nature and extent of soil disturbance resulting from stump harvesting by the application of additional techniques. In this way the physical effects of soil disturbance by stump harvesting will be compared with those of other forestry practices. To overcome the two-dimensional and subjective nature of visual assessment, a radiometric approach was adopted, utilising residual Chernobyl 137Cs fallout to determine the degree of soil mixing. To complement bulk density measurements, micromorphological analyses of soil thin sections taken from field samples were carried out to investigate the impact of compressive force on pore space. Low-cost tracer devices were deployed in the soil around stumps prior to extraction to permit the monitoring of the lateral movement of soil during stump extraction. These methods were applied to a stump harvesting operation carried out under current UK guidance at a UPM Tilhill managed site in south west Scotland. The radiometric method demonstrated its capacity to recognise differing degrees of soil disturbance in an operational forest environment, including some disturbance that might escape visual assessment. Analysis of soil thin sections provided the evidence of a significant increase in the pore capacity of disturbed soil. The soil movement tracers developed for this project provided the capability to examine the various trajectories of soil during stump extraction as well as dimensioning the resulting disturbance crater. The study indicated that under current UK management and operational practice, stump harvesting generated a higher level of soil disturbance compared to ground preparation by trench mounding, with an estimated 1260 m3 ha-1 of soil disturbed by stump harvesting compared to 250 m3 ha-1 from trench mounding. Stump harvesting was found to generate a net reduction in soil bulk density in the affected areas, contrary to the findings of some other studies. This outcome is dependent on adhering to particular site management and operational procedures. The practice of raking over the site following stump harvesting is estimated to add a further 10% to the volume of soil disturbed, and is a questionable activity under soil sustainability guidance. This work was part-funded and actively supported by the UK Forestry Commission and UPM Tilhill.

Este sumário apresenta o resumo e os resultados deste estudo experimental do Fechamento do Coto Duodenal, em um e dois planos de sutura, realizado em 48 cães submetidos a uma gastrectomia Billroth II, com a finalidade de estudar comparativamente, o processo de cicatrização, macro e microscópico da sutura deste Coto. Os aspectos mais relevantes deste estudo de cicatrização de feridas macroscópicas e microscópicas no coto duodenal foram os seguintes: A) Estudo macroscópico: Com o objetivo de realizar um estudo macroscópico de fechamento do coto duodenal, foi realizada uma gastrectomia BII, em 48 cães, divididos em dois grupos: Grupo 1 - composto por 24 cães em que a sutura do coto duodenal foi realizada em um plano extra-mucoso. Estes animais foram divididos em dois subgrupos de 12 animais cada: i1 - cães sacrificados no período pós-operatório imediato, ou seja, no primeiro, quarto e sétimo dia após a operação; e M1 - cães sacrificados em um período pós-operatório mais tardio, ou seja, no décimo quarto, vigésimo primeiro e vigésimo oitavo dia, após a operação. Grupo 2 - Composto por 24 animais, em que a sutura do coto duodenal foi realizada em 2 planos (total e seromuscular). Também estes animais foram distribuídos em subgrupos, i2 e M2, de forma idêntica como no Grupo 1. Um estudo comparativo foi feito quanto aos resultados de fechamento do coto duodenal em 1 e 2 planos, levando em consideração seus aspectos macroscópicos, obtendo-se as seguintes conclusões: o Em nenhum dos cães, em ambos os grupos, ocorreu deiscência do coto duodenal ou quaisquer outras complicações pós-operatórias; o O diâmetro externo do coto duodenal ao nível da sutura foi significativamente maior no grupo com 2 planos de sutura. No entanto, a 5 e 10 cm distalmente à sutura do coto, esta medida foi semelhante em ambos os grupos. o Aderências ao coto duodenal foram semelhantes em ambos os métodos de sutura, exceto por uma incidência significativamente maior de aderências de epíplon no grupo com um plano de sutura, durante os primeiros 7 dias. o A inflamação da mucosa foi significativamente maior no grupo com 2 planos de sutura, durante os primeiros 7 dias; o O esporão formado no fechamento do coto em 2 planos de sutura foi significativamente maior que o formado em um plano de sutura. o A distância entre a superfície mucosa do coto duodenal e a papila maior e papila menor do duodeno, foi significativamente maior nos cotos fechados com 1 plano de sutura. B) O estudo histológico: Um estudo histológico de fechamento do coto duodenal foi feito, após gastrectomia Billroth II em 48 cães, divididos em dois grupos iguais. No Grupo 1, o fechamento foi realizada em um plano, enquanto no Grupo 2 foi feito em dois planos (total e seromuscular). Em cada grupo, os animais foram divididos em dois subgrupos; i1 - cães sacrificados no início do período pós-operatório, ou seja, no primeiro, quarto e sétimo dias; e M1 - cães sacrificados no pós-operatório tardio, ou seja, no décimo quarto, vigésimo primeiro e vigésimo oitavo dia. Não houve um único caso de deiscência em qualquer animal. As conclusões relativas aos aspectos histológicos mostraram os seguintes aspectos: o Houve um esporão invertido para o lúmen do intestino, em todos os animais do grupo 2, enquanto que um pseudoesporão foi observado em apenas 37% nos animais do Grupo 1 ; o Sinais inflamatórios agudos foram mais intensos no grupo 2, na primeira semana de pós-operatório; o A formação de neofibrose do tecido conjuntivo e a regeneração da \"muscularis mucosae\" foi semelhante nos dois grupos. No entanto, a regeneração da mucosa ocorreu mais precocemente no grupo 1 , ao passo que a regeneração das fibras musculares ocorreu mais precocemente no grupo 2 / An experimental study of duodenal stump closure in one and two suture layers was performed in 48 dogs submitted to a Billroth II Gastrectomy, in order to study comparatively Macroscopic and Histological wound healing aspects. The most relevant aspects of this Macroscopic and Histological wound healing study in the duodenal stump, were the following ones: A) Macroscopic study: A comparative study was made as to the results of duodenal stump closure in 1 and 2 layers, taking in consideration its macroscopic aspects. Billroth II gastrectomy was performed in 48 dogs divided in two groups: a. Group 1 - consisted of 24 dogs in which the duodenal stump suture was performed in one extra-mucous layer. These animals were distributed into 2 subgroups of 12 animals each: i1 - dogs sacrificed in the early postoperative period, that is, on the first, fourth and seventh day after the operation; and M1 - dogs sacrificed at a later postoperative period, that is, on the fourteenth, twenty-first and twenty-eighth day after the operation. b. Group 2 - consisted of 24 dogs, in which the suture of the duodenal stump was performed in 2 layers (total and seromuscular ones). Also these animals were distributed in i2 and M2 sub-groups, identically as in group 1. The following conclusions were obtained, concerning the macroscopic aspects: o Dehiscence of the duodenal stump or any other postoperative complications occurred in none of the dogs in both groups; o The external diameter of the duodenal stump at the level of the suture was significantly larger in the group with 2 suture layers. However, at 5 and 10 cm distally from the suture, this measure was similar in both groups. o Adherences to the duodenal stump were similar in both suturing methods, except for a significantly higher incidence of epiplon adherence in the 1 layer group during the first 7 days. o Mucosal inflammation was significantly greater in the 2 suture layers group during the first 7 days; o The spurs formed in the 2 layers stump closure was significantly larger than that formed in 1 layer suture. o The distance from the mucosal surface of the stump suture to the Major and Minor papilla of the duodenum was significantly greater in the stumps closed with 1 layer sutures. B) Histological study: A histological study of duodenal stump closure was made, following a Billroth II gastrectomy in 48 dogs, divided in two equal groups (1 and 2) and its subgroups (i1 and M1; i2 and M2), as mentioned above. The conclusions concerning to histological aspects showed the following characteristics: o There was an inverted spur toward the lumen of the bowel, in all group 2 animals, whereas a pseudo- spur was also observed in only 37% in group 1 animals; o Acute inflammatory signs were more intense in group 2 in the first week of recovery; o The formation of young connective tissue fibrosis and muscularis mucosae fibers regeneration was similar in both groups. However, mucosal regeneration occurred earlier in group 1, while regeneration of muscle fibers occurred more precociously in group 2

Ondskans problem är ett gammalt (religions)filosofiskt problem som, i grova drag, frågar om existensen av en allsmäktig, allvetande och allgod Gud är förenlig med ondskan i världen, samt varför en sådan Gud tillåter ondska. Filosofer (som svarar jakande på frågan om) har utvecklat ett svar på frågan varför Gud tillåter ondska. Syftet med denna uppsats är följaktligen att redogöra för Richard Swinburnes svar på frågan varför Gud tillåter ondska, samt granska svaret i ljuset av Eleonore Stumps tankegångar.

Resumo: O eucalipto é a arbórea mais plantada no Brasil, devido ao seu amplo uso e após seu corte, os tocos e raízes que permanecem no local, dificultam o manejo da cultura. Com base nessa necessidade, o objetivo do presente estudo foi avaliar as características fisiológicas e funcionais de fungos basidiomicotas, isolados de campos de reflorestamento de Eucalyptus spp., com vistas à possibilidade do uso destes na destoca natural. Os fungos Pycnoporus sanguineus, Lentinus bertieri, Xylaria sp. e Lentinula edodes e um isolado não identificado foram estudados. No primeiro experimento, avaliou-se a patogenicidade dos mesmos em plantas de eucalipto urograndis (10 meses de idade), através da inoculação de disco de meio de cultura colonizado e não colonizado (Testemunha). As avaliações foram feitas aos 30 e 60 dias após a inoculação, com base no tamanho das lesões internas e externas. No segundo experimento, avaliou-se o crescimento micelial dos fungos P. sanguineus, L. bertieri, Xylaria sp., L. edodes e S. ostrea, em substrato à base de serragem enriquecida com farelos, e em três composições de meios de cultura, Batata-Dextrose-Ágar (BDA); Malte-Ágar (MA) e Serragem-Dextrose-Ágar (SDA), e incubados a 23, 27 e 31ºC. No terceiro experimento, avaliou-se a produção das enzimas ligninocelulolíticas lacase e celulase, e outras ligadas à degradação de tecidos vegetais, as proteases, pectinases e lipase, em meios de cultura específicos. No quarto experimento, estudou-se, pelo método "soil block", a perda de massa (%) de corpos-de-prova de eucalipto urograndis, inoculados com os fungos P. sanguineus, L. bertieri, Xylaria sp. e L. edodes, mantidos sob dois regimes de umidade (50 e 100%), e avaliados aos 30, 60, 90 e 120 após inoculação. Estudaram-se também as características químicas da madeira, após 120 dias da inoculação / Abstract: The Eucalyptus spp. tree is the most planted in Brazil, due to its widespread use and after its use, the stumps and roots that remains in the area, hinder crop management. Based on this need, the purpose of this work was evaluate the physiological and functional characteristics of basidiomycetes fungi, obtained in reforestation fields of Eucalyptus spp., with the possibility of using the fungi in natural stump removal. Pycnoporus sanguineus, Lentinus bertieri, Xylaria sp., Stereum ostrea and a unidentified isolate, were studied. In the first, was evaluate the fungi pathogenicity in eucalipt urograndis plants (10 months old), by means of disk inoculation into culture medium colonized and non-colonized (control) by fungi. Evaluations were performed at 30 and 60 days after inoculation based on the external and internal size of lesions. In experiment 2, the mycelial growth of P. sanguineus, L. bertieri, Xylaria sp., L. edodes and S. ostrea was evaluated in bran and sawdust-based substrate, as well as in three culture media: Potato-Dextrose-Agar (PDA), Malt-Agar (MA) and Sawdust-Dextrose-Agar (SDA), and at three incubation temperatures, at 23, 27 and 31ºC. In experiment 3, the production of lignolytic enzymes lacase and cellulase, and other enzymes related to degradation of plant tissues, like protease, pectinases and lipase was assessed in specific culture media. In experiment 4, mass loss (%) and chemical features of eucalipt urograndis wood degraded by the soil block method were evaluated by the P. sanguineus, L. bertieri, Xylaria sp. and L. edodes fungi. Thus, test specimens were inoculated with the fungi and kept under two moisture regimes, 50 and 100%, and incubated at 25 ±2ºC. Mass loss was assessed at 30, 60, 90 and 120 days after inoculation. The chemical features of eucalipt urograndis test specimens were only analyzed at 120 days / Orientador: Marli Teixeira de Almeida Minhoni / Coorientador: Edson Luiz Furtado / Banca: Celso Garcia Auer / Banca: Elias Taylor Durgante Severo / Mestre

Este sumário apresenta o resumo e os resultados deste estudo experimental do Fechamento do Coto Duodenal, em um e dois planos de sutura, realizado em 48 cães submetidos a uma gastrectomia Billroth II, com a finalidade de estudar comparativamente, o processo de cicatrização, macro e microscópico da sutura deste Coto. Os aspectos mais relevantes deste estudo de cicatrização de feridas macroscópicas e microscópicas no coto duodenal foram os seguintes: A) Estudo macroscópico: Com o objetivo de realizar um estudo macroscópico de fechamento do coto duodenal, foi realizada uma gastrectomia BII, em 48 cães, divididos em dois grupos: Grupo 1 - composto por 24 cães em que a sutura do coto duodenal foi realizada em um plano extra-mucoso. Estes animais foram divididos em dois subgrupos de 12 animais cada: i1 - cães sacrificados no período pós-operatório imediato, ou seja, no primeiro, quarto e sétimo dia após a operação; e M1 - cães sacrificados em um período pós-operatório mais tardio, ou seja, no décimo quarto, vigésimo primeiro e vigésimo oitavo dia, após a operação. Grupo 2 - Composto por 24 animais, em que a sutura do coto duodenal foi realizada em 2 planos (total e seromuscular). Também estes animais foram distribuídos em subgrupos, i2 e M2, de forma idêntica como no Grupo 1. Um estudo comparativo foi feito quanto aos resultados de fechamento do coto duodenal em 1 e 2 planos, levando em consideração seus aspectos macroscópicos, obtendo-se as seguintes conclusões: o Em nenhum dos cães, em ambos os grupos, ocorreu deiscência do coto duodenal ou quaisquer outras complicações pós-operatórias; o O diâmetro externo do coto duodenal ao nível da sutura foi significativamente maior no grupo com 2 planos de sutura. No entanto, a 5 e 10 cm distalmente à sutura do coto, esta medida foi semelhante em ambos os grupos. o Aderências ao coto duodenal foram semelhantes em ambos os métodos de sutura, exceto por uma incidência significativamente maior de aderências de epíplon no grupo com um plano de sutura, durante os primeiros 7 dias. o A inflamação da mucosa foi significativamente maior no grupo com 2 planos de sutura, durante os primeiros 7 dias; o O esporão formado no fechamento do coto em 2 planos de sutura foi significativamente maior que o formado em um plano de sutura. o A distância entre a superfície mucosa do coto duodenal e a papila maior e papila menor do duodeno, foi significativamente maior nos cotos fechados com 1 plano de sutura. B) O estudo histológico: Um estudo histológico de fechamento do coto duodenal foi feito, após gastrectomia Billroth II em 48 cães, divididos em dois grupos iguais. No Grupo 1, o fechamento foi realizada em um plano, enquanto no Grupo 2 foi feito em dois planos (total e seromuscular). Em cada grupo, os animais foram divididos em dois subgrupos; i1 - cães sacrificados no início do período pós-operatório, ou seja, no primeiro, quarto e sétimo dias; e M1 - cães sacrificados no pós-operatório tardio, ou seja, no décimo quarto, vigésimo primeiro e vigésimo oitavo dia. Não houve um único caso de deiscência em qualquer animal. As conclusões relativas aos aspectos histológicos mostraram os seguintes aspectos: o Houve um esporão invertido para o lúmen do intestino, em todos os animais do grupo 2, enquanto que um pseudoesporão foi observado em apenas 37% nos animais do Grupo 1 ; o Sinais inflamatórios agudos foram mais intensos no grupo 2, na primeira semana de pós-operatório; o A formação de neofibrose do tecido conjuntivo e a regeneração da \"muscularis mucosae\" foi semelhante nos dois grupos. No entanto, a regeneração da mucosa ocorreu mais precocemente no grupo 1 , ao passo que a regeneração das fibras musculares ocorreu mais precocemente no grupo 2 / An experimental study of duodenal stump closure in one and two suture layers was performed in 48 dogs submitted to a Billroth II Gastrectomy, in order to study comparatively Macroscopic and Histological wound healing aspects. The most relevant aspects of this Macroscopic and Histological wound healing study in the duodenal stump, were the following ones: A) Macroscopic study: A comparative study was made as to the results of duodenal stump closure in 1 and 2 layers, taking in consideration its macroscopic aspects. Billroth II gastrectomy was performed in 48 dogs divided in two groups: a. Group 1 - consisted of 24 dogs in which the duodenal stump suture was performed in one extra-mucous layer. These animals were distributed into 2 subgroups of 12 animals each: i1 - dogs sacrificed in the early postoperative period, that is, on the first, fourth and seventh day after the operation; and M1 - dogs sacrificed at a later postoperative period, that is, on the fourteenth, twenty-first and twenty-eighth day after the operation. b. Group 2 - consisted of 24 dogs, in which the suture of the duodenal stump was performed in 2 layers (total and seromuscular ones). Also these animals were distributed in i2 and M2 sub-groups, identically as in group 1. The following conclusions were obtained, concerning the macroscopic aspects: o Dehiscence of the duodenal stump or any other postoperative complications occurred in none of the dogs in both groups; o The external diameter of the duodenal stump at the level of the suture was significantly larger in the group with 2 suture layers. However, at 5 and 10 cm distally from the suture, this measure was similar in both groups. o Adherences to the duodenal stump were similar in both suturing methods, except for a significantly higher incidence of epiplon adherence in the 1 layer group during the first 7 days. o Mucosal inflammation was significantly greater in the 2 suture layers group during the first 7 days; o The spurs formed in the 2 layers stump closure was significantly larger than that formed in 1 layer suture. o The distance from the mucosal surface of the stump suture to the Major and Minor papilla of the duodenum was significantly greater in the stumps closed with 1 layer sutures. B) Histological study: A histological study of duodenal stump closure was made, following a Billroth II gastrectomy in 48 dogs, divided in two equal groups (1 and 2) and its subgroups (i1 and M1; i2 and M2), as mentioned above. The conclusions concerning to histological aspects showed the following characteristics: o There was an inverted spur toward the lumen of the bowel, in all group 2 animals, whereas a pseudo- spur was also observed in only 37% in group 1 animals; o Acute inflammatory signs were more intense in group 2 in the first week of recovery; o The formation of young connective tissue fibrosis and muscularis mucosae fibers regeneration was similar in both groups. However, mucosal regeneration occurred earlier in group 1, while regeneration of muscle fibers occurred more precociously in group 2

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21807号 / 農博第2320号 / 新制||農||1065(附属図書館) / 学位論文||H31||N5179(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 大澤 晃, 教授 北島 薫, 教授 神﨑 護 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM