title: Linear acoustic waves in a nonisothermal atmosphere. II. photospheric resonator model of three-minute umbral oscillations

authors: Chae, Jongchul

subjects: Science & Technology

abstract: The velocity oscillations observed in the chromosphere of sunspot umbrae resemble a resonance in that their power spectra are sharply peaked around a period of about three minutes. In order to describe the resonance that leads to the observed 3-minute oscillations, we propose the photospheric resonator model of acoustic waves in the solar atmosphere. The acoustic waves are driven by the motion of a piston at the lower boundary, and propagate in a nonisothermal atmosphere that consists of the lower layer (photosphere), where temperature rapidly decreases with height, and the upper layer (chromosphere), where temperature slowly increases with height. We have obtained the following results: (1) The lower layer (photosphere) acts as a leaky resonator of acoustic waves. The bottom end is established by the piston, and the top end by the reflection at the interface between the two layers. (2) The temperature minimum region partially reflects and partially transmits acoustic waves of frequencies around the acoustic cutoff frequency at the temperature minimum. (3) The resonance occurs in the photospheric layer at one frequency around this cutoff frequency. (4) The waves escaping the photospheric layer appear as upwardpropagating waves in the chromosphere. The power spectrum of the velocity oscillation observed in the chromosphere can be fairly well reproduced by this model. The photospheric resonator model was compared with the chromospheric resonator model and the propagating wave model.

text: Linear acoustic waves in a nonisothermal atmosphere. II. photospheric resonator model of three-minute umbral oscillations The velocity oscillations observed in the chromosphere of sunspot umbrae resemble a resonance in that their power spectra are sharply peaked around a period of about three minutes. In order to describe the resonance that leads to the observed 3-minute oscillations, we propose the photospheric resonator model of acoustic waves in the solar atmosphere. The acoustic waves are driven by the motion of a piston at the lower boundary, and propagate in a nonisothermal atmosphere that consists of the lower layer (photosphere), where temperature rapidly decreases with height, and the upper layer (chromosphere), where temperature slowly increases with height. We have obtained the following results: (1) The lower layer (photosphere) acts as a leaky resonator of acoustic waves. The bottom end is established by the piston, and the top end by the reflection at the interface between the two layers. (2) The temperature minimum region partially reflects and partially transmits acoustic waves of frequencies around the acoustic cutoff frequency at the temperature minimum. (3) The resonance occurs in the photospheric layer at one frequency around this cutoff frequency. (4) The waves escaping the photospheric layer appear as upwardpropagating waves in the chromosphere. The power spectrum of the velocity oscillation observed in the chromosphere can be fairly well reproduced by this model. The photospheric resonator model was compared with the chromospheric resonator model and the propagating wave model.

year: 2019

title: The State and Sexual Politics: An Analysis of Abortion Discourses in Kenya

authors: Njagi, Jane Wambui

subjects: Abortion

abstract: Unsafe abortion, an issue that leads to over 2,000 deaths and health complications for more than 21,000 women annually in Kenya, remains largely unaddressed by the Kenyan state. Despite the significant public importance of abortion, there has been little or no scholarly attention directed at the role of the state in shaping sexual politics through its regulation of abortion. In this thesis, I undertake a feminist analysis of the Kenyan state to explore how the state, through its policy regime, shapes sexual politics.   
I argue that Western-based feminist theorisations of the state, although useful, do not fully account for the Kenyan state’s treatment of the issue of abortion. Consequently, I draw on the range of scholarship in feminist theorisations of the state and in African politics to develop the Critical African Feminist Perspective on the state. Using this perspective, I undertake a discourse analysis of archival material, policy texts, and interviews with key actors in abortion politics.  The analysis of the state over three phases – colonial, dictatorial, and democratic – reveals the neo-patrimonial character of the state, resulting in policies and practices that systematically ignore or marginalise issues affecting women. 
This study demonstrates that across consecutive governments, the Kenyan political elite, in an attempt to consolidate political power and popularity in the face of low levels of legitimacy and complex tribal politics, has deployed a tactic of “strategic ambivalence”, wherein the law criminalising abortion has been sustained but not enforced. State efforts have therefore been directed at presenting a positive image of itself to both pro- and anti-abortion actors, rather than substantively tackling the problem of unsafe abortion.
The study establishes that although neoliberalism, capitalism and patriarchy play significant roles, neo-patrimonial politics is the key impediment to creating policies and institutions that will ensure Kenyan women’s access to safe abortions. I note that although Kenya’s new Constitution guarantees women better access to legal abortion, it has not conclusively addressed neo-patrimonialism, which is therefore likely to continue to have negative implications for sexual politics and issues of gender equality in general.

text: The State and Sexual Politics: An Analysis of Abortion Discourses in Kenya Unsafe abortion, an issue that leads to over 2,000 deaths and health complications for more than 21,000 women annually in Kenya, remains largely unaddressed by the Kenyan state. Despite the significant public importance of abortion, there has been little or no scholarly attention directed at the role of the state in shaping sexual politics through its regulation of abortion. In this thesis, I undertake a feminist analysis of the Kenyan state to explore how the state, through its policy regime, shapes sexual politics.   
I argue that Western-based feminist theorisations of the state, although useful, do not fully account for the Kenyan state’s treatment of the issue of abortion. Consequently, I draw on the range of scholarship in feminist theorisations of the state and in African politics to develop the Critical African Feminist Perspective on the state. Using this perspective, I undertake a discourse analysis of archival material, policy texts, and interviews with key actors in abortion politics.  The analysis of the state over three phases – colonial, dictatorial, and democratic – reveals the neo-patrimonial character of the state, resulting in policies and practices that systematically ignore or marginalise issues affecting women. 
This study demonstrates that across consecutive governments, the Kenyan political elite, in an attempt to consolidate political power and popularity in the face of low levels of legitimacy and complex tribal politics, has deployed a tactic of “strategic ambivalence”, wherein the law criminalising abortion has been sustained but not enforced. State efforts have therefore been directed at presenting a positive image of itself to both pro- and anti-abortion actors, rather than substantively tackling the problem of unsafe abortion.
The study establishes that although neoliberalism, capitalism and patriarchy play significant roles, neo-patrimonial politics is the key impediment to creating policies and institutions that will ensure Kenyan women’s access to safe abortions. I note that although Kenya’s new Constitution guarantees women better access to legal abortion, it has not conclusively addressed neo-patrimonialism, which is therefore likely to continue to have negative implications for sexual politics and issues of gender equality in general.

year: 2013

title: He aha te mea nui o te ao? He tāngata! (What is the most important thing in the world? It is people!)

authors: Masters-Awatere, Bridgette

subjects: chronic disease prevention

abstract: This paper highlights the importance of people as a central factor in improving health for M aori (Indigenous people of New Zealand). How wh anau (family) relationships, connections, values and inspiration are integral to achieving Indigenous health goals is explained. Descriptions of how community researchers, healthcare staff, consumers and academics worked together to design interventions for two health services (in the Waikato and Bay of Plenty regions) is included. Through highlighting the experiences of health consumers, the potential for future interventions to reduce the advancement of pre-diabetes among wh anau is described. Evidence from the study interviews reinforces the importance of wh anau and whakapapa (heritage) as enabling factors for Indigenous people to improve health. Specifically, the positive effect of wh anau enhancing activities that support peoples’ aspirations of tino rangatiratanga (self-determination) in their lives when engaging with health care has been observed. This study highlights the many positives that have emerged, and offers an opportunity for taking primary health to the next level by placing wh anau alongside Indigenous primary care providers at the centre of change strategies.

text: He aha te mea nui o te ao? He tāngata! (What is the most important thing in the world? It is people!) This paper highlights the importance of people as a central factor in improving health for M aori (Indigenous people of New Zealand). How wh anau (family) relationships, connections, values and inspiration are integral to achieving Indigenous health goals is explained. Descriptions of how community researchers, healthcare staff, consumers and academics worked together to design interventions for two health services (in the Waikato and Bay of Plenty regions) is included. Through highlighting the experiences of health consumers, the potential for future interventions to reduce the advancement of pre-diabetes among wh anau is described. Evidence from the study interviews reinforces the importance of wh anau and whakapapa (heritage) as enabling factors for Indigenous people to improve health. Specifically, the positive effect of wh anau enhancing activities that support peoples’ aspirations of tino rangatiratanga (self-determination) in their lives when engaging with health care has been observed. This study highlights the many positives that have emerged, and offers an opportunity for taking primary health to the next level by placing wh anau alongside Indigenous primary care providers at the centre of change strategies.

year: 2019