Results_Controller

Error from log

Started POST "/results" for xxx.xxx.xxx.xxx at 2011-02-02 16:57:44 -0500
  Processing by ResultsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"x1Fxj2OGNfbGs6fDskHa7jB3LhJswDkEUG4BYOx2iBw=", "result"=>{"title"=>"Testing", "short_url"=>"test", "result_file"=>#<ActionDispatch::Http::UploadedFile:0xba42ae4 @original_filename="ljrind11.htm", @content_type="text/html", @headers="Content-Disposition: form-data; name=\"result[result_file]\"; filename=\"ljrind11.htm\"\r\nContent-Type: text/html\r\n", @tempfile=#<File:/tmp/RackMultipart20110202-29224-1qc2x8y>>, "created_at(1i)"=>"2011", "created_at(2i)"=>"2", "created_at(3i)"=>"2"}, "commit"=>"Upload"}
Completed   in 232ms

Errno::EACCES (Permission denied - /var/apps/nests/public/tmp/results):
  app/controllers/results_controller.rb:18:in `create'

gistfile1.rb

class ResultsController < ApplicationController
  before_filter :authenticate_admin!, :except => [:index, :show]
  respond_to :html, :xml
  def index
    @results = Result.find(:all, :order => 'created_at DESC').paginate(:page => params[:page])
  end

  def show
    @result = Result.find_by_short_url(params[:id]) || Result.find_by_id(params[:id]) 
    respond_with(@result, :location => result_path)
  end

  def new
    @result = Result.new
  end
  
  def create
    @result = Result.create(params[:result])
    if @result.save
      flash[:success] = 'Result uploaded successfully!'
      respond_with(@result, :location => @result)
    else
      flash[:error] = 'Upload failed.'
      respond_with(@result, :location => new_result_path)
    end
  end
  
  def edit
    @result = Result.find(params[:id])
  end
  
  def update
    @result = Result.find(params[:id])
    if @result.update_attributes(params[:result])
       flash[:success] = 'Result was successfully updated.'
       respond_with(@result, :location => results_path)
    else
      flash[:error] = 'Oh snap. The hampsters stopped running. Try again.'
      respond_with(@result, :location => edit_result_path)
    end
  end
  
  def destroy
    @result = Result.find_by_short_url(params[:id])
    @result.destroy
      flash[:success] = "The result was terminated. Pew pew pew."
      respond_with(nil, :location => results_path)
  end
end

result.rb

class Result < ActiveRecord::Base
  
  cattr_reader :per_page
  @@per_page = 30
  
  def to_param
    short_url
  end
  
  mount_uploader :result_file, ResultFileUploader
  
  validates :title, :presence => true,
                    :length => {:minimum => 5}

  validates :short_url, :presence => true,
                        :uniqueness => true                           
end